FR2914780A1 - TANDEM MASS SPECTROMETRY METHOD WITHOUT PRIMARY MASS SELECTION. - Google Patents

Abstract

According to the invention, a tandem mass spectrometry method without primary mass selection is proposed, comprising the following steps: a primary mass spectrum is generated without dissociation, it is determined for each of the primary mass peaks that it contains the the value of the mass-charge ratio function of the primary ions of the mass spectrometer used corresponding to the maximum number of occurrences of this peak, and the electric charge of the primary ions, and from these data, correlation laws giving all the possible pairs and trios of values of the mass-to-charge ratio function of the dissociated charged fragments of the mass spectrometer used, corresponding to maxima of occurrences of possible pairs and trios of dissociation mass peaks produced by pairs and trios of fragments loaded with mass-to-charge ratios likely to come from the dissociation of identical primary ions having the same mass-to-charge ratio, - primary ions are dissociated without primary mass selection, at low kinetic energy, so as to obtain for each of them, a pair, or a trio, of charged fragments, - a spectrum of dissociation without selection of primary mass, then from this spectrum, for each of the dissociation mass peaks it contains each value of the function of the mass-to-charge ratio of the dissociated charged fragments of the mass spectrometer used corresponding to the maximum of occurrences of this peak, all the potential pairs and trios of these values are generated from the measured values, then identifying, among said potential pairs and trios, the actual pairs and trios which satisfy a criterion of proximity by relative to the correlation laws, and each dissociation spectrum corresponding to each of the primary mass peaks is produced, with the pairs and trios of dissociation mass peaks ion corresponding to the actual pairs and trios identified.

Description

Field of the invention

  The invention relates to a tandem mass spectrometry method without primary mass selection. State of the art

  As a reminder, mass spectrometry (MS), of whatever type, generally comprises the steps of identifying molecules present in a sample by measuring the mass of these molecules after being ionized, accelerated and introduced into a sample. mass spectrometer. The mass spectrometer produces a mass spectrum of the various molecules contained in the sample analyzed as a function of the value of the mass-to-charge ratio (M / Q) (M being the mass and Q the charge) of the ions produced in the form of of the intensity of the ion current detected by an ion detector as a function of the variation of a function F (M / Q) of the value of the mass-to-charge ratio of the ions which depends on the mass spectrometer used, which is generally of the form: F (M / Q) = G x (M / Q), where G is a function which depends on the type of spectrometer used independent of the mass-to-charge ratio of the ions.

  The main types of mass spectrometers used are time-of-flight mass spectrometers, magnetic sector spectrometers, quadrupole mass spectrometers, 3D (hyperbolic geometry) or linear 2D (cylindrical geometry) traps, and FTICR Fourier Transform Ion Cyclotron Resonance mass spectrometer. The specific operating modes of each type of mass spectrometer mentioned above, and their different variants are known to those skilled in the art. In the case of time-of-flight mass spectrometers, we have: F (M / Q) = TOF2 (M / Q) = GTOF x (M / Q), where TOF is the flight time of the ions. for a linear flight time, we have: GTOF = (L2 / 2 Vo), where L is the distance of the linear flight time between the pulsation of the ion packet and the ion detector, and Vo is the voltage of ion acceleration.

  In the case of magnetic sector mass spectrometers one has: F (M / Q) = B2 (M / Q) = GB x (M / Q), where B is the variable magnetic field applied in the magnetic sector allowing to filter ions as a function of their charge mass ratio towards an ion detection.

  For example, for a single-focus magnetic sector, we have: GB = (2 Vo / RZ) (M / Q), where R is the radius of the magnetic sector and Vo is the acceleration voltage of the ions. In the case of quadrupole mass spectrometers we have: F (M / Q) = VQ (M / Q) = GQ x (M / Q), where VQ is the variable voltage applied in the quadrupole to filter the ions as a function of their mass-to-charge ratio to an ion detector. In the case of mass spectrometers of the ion trap type we have: F (M / Q) = VIT (M / Q) = GIT x (M / Q), where VIT is the variable voltage applied in the ion trap for eject ions based on their mass-to-charge ratio to an ion detector. In the case of Fourier Transform Ion Cyclotron Resonance Fourier Transform mass spectrometers we have: F (M / Q) = {1 / (&) FTICR (M / Q)} = GFTICR x (M / Q) , where 0) FTICR is the cyclotron frequency corresponding to each charge mass ratio (M / Q) value of the ions whose measurement and analysis by Fourier transform makes it possible to produce the mass spectrum of the ions.

  There is also tandem mass spectrometry (MS-MS), generally used when the primary mass spectrum (MS) does not identify the molecules studied. It generally comprises the steps of producing, by means of a first mass spectrometer, a primary mass spectrum (MS) of the ionized molecules present in the sample analyzed, to carry out a step of selecting a mass primary, then to fragment, or otherwise dissociate, with a dissociation system the primary ions of said selected primary mass, so as to produce a so-called dissociation mass spectrum of charged fragments from the dissociation of these primary ions to the using a second mass spectrometer. Primary mass selection to achieve each dissociation mass spectrum limits the acquisition rate of the tandem mass spectrometer used because each mass spectrum is produced successively.

  It also limits the sensitivity of the tandem mass spectrometer used, defined as the amount of sample consumed to produce each dissociation mass spectrum, since the other unselected primary ions provided by the ion source are removed to produce the dissociation spectrum of the selected primary ions.

  Dissociation of primary ions can be performed at high kinetic energy (0.2-20 keV) or at low kinetic energy (û10-200 eV). In the case of low kinetic energy dissociation the measurement of the mass-to-charge ratio (m / q) of the dissociated charged fragments is generally obtained in the same way as that of the parent primary ions in the form of the current intensity of the ions detected by an ion detector as a function of the variation of a function F (m / q) of the mass-to-charge ratio (m / q) which depends on the mass spectrum used which is also of the form: F (m / q) = G x (m / q), where G is a function that depends on the type of spectrometer used independent of the mass-to-charge ratio of the ions. The F function of the mass spectrometer used does not depend on the kinetic energy of the undissociated primary ions and the charged fragments, because either the undissociated primary ions and the charged fragments are accelerated to the same kinetic energy before the mass spectrometer. either the G-function of the mass spectrometer used to produce the dissociation spectra does not depend on the kinetic energy of the ions.

  In the case of high kinetic energy dissociation, the F '(m / q) function of the mass spectrometer used depends on the kinetic energy of the dissociated charged fragments, since the kinetic energy of the dissociated charged fragments depends on the mass of the fragments. . For the same mass spectrometer used, the function F (M / Q) for the measurement of the mass-to-charge ratio of the undissociated primary ions is therefore different from the function F '(m / q) for the measurement of the mass-to-charge ratio. dissociated charged fragments. The function F '(m / q) can not generally be in the form: F' (m / q) = G 'x (mlq), where G' would be a function that would depend on the mass spectrum used independent of the ratio mass on charge of the dissociated charged fragments.

  In the particular case of time-of-flight mass spectrometry, in addition to the tandem flight time mass spectrometers previously described with the primary mass selection, tandem flight time mass spectrometers without selection are also known. primary mass. They make it possible to produce several dissociation mass spectra simultaneously. Time-of-flight mass spectrometry methods without primary mass selection are thus known [1] [2] [3] [4], which nevertheless require several acquisitions to produce the different dissociation spectra, but with a number of successive acquisitions compared to devices using primary mass selection. In particular, a tandem flight time mass spectrometry method is known which makes it possible to produce a plurality of dissociation mass spectra without primary mass selection in a single acquisition [5]. This method of time-of-flight mass spectrometry without primary mass selection is based on the transformation of flight times into measured positions [5]. This method limits the primary mass range accessible simultaneously. The methods [1], [2], [3], [4], and [5] are only compatible with dissociation of the primary ions with high kinetic energy.

  The dissociation of the mono-charged primary ions is simple, and generally limited to the production of neutral and mono-charged fragment pairs. The dissociation of the multicharged primary ions can be complex and give rise to several possible dissociation channels [6]. The two main families of dissociation channels are fragment fragmentation and fragmentation into fragments (dissociation into a larger number of fragments is possible but generally less likely). If we denote M and Q respectively the mass and the electric charge of the parent primary ion and: mi and q; are the mass and the charge of each dissociated fragment i (with i = 1, 2 and 3), the two main channels of dissociation in pairs of fragments are [6]: (a) M (Q) - * mi (qi ) + m2 (q2), with mi + m2 = M and ql + q2 = Q, (b) M (Q) where mi (qi = Q) + m2 (q2 = 0), with mi + m2 = M, 15 and the three main channels of dissociation into trio of fragments are [6]: (c) M (Q) where mi (qi) + m2 (q2) + m3 (q3), with mi + m2 + m3 = M and qi + q2 + q3 = Q, (d) M (Q) -> mi (qi) + m2 (q2) + m3 (q3 = 0), with mi + m2 + m3 = M and qi + q2 = Q, ( e) M (Q) ù * mi (qi = Q) + m2 (q2 = 0) + m3 (q3 = 0), with mi + m2 + m3 = M. In some cases of dissociation the parent primary ion can lose an electron during dissociation (as for example sometimes in the collision induced collision induced collision (CID) dissociation with molecules of a gas with charge) or can recover an electron (as for example in the case of dissociation by ECD (acronym for "Electron Capture Dissociation") by electron capture). In this case, the sum of the charges of the fragments is equal to Q '= Q + (or -) e, instead of Q (where e is the unit of electric charge). There is currently no known mass spectrometry method capable of producing all the dissociation spectra without primary mass selection in a single acquisition and without limitation of the primary mass range, and using low kinetic energy dissociation.

  There is no universal tandem mass spectrometry method to produce multiple dissociation spectra simultaneously without primary mass selection for multicharged and / or mono-charged primary ions compatible with all existing mass spectrometry techniques. Summary of the invention

  An object of the invention is therefore to overcome the disadvantages of the state of the art presented in particular above, in the case of multicharged primary ions 10 and / or mono charged. In particular, an object of the invention is in particular to propose a method of mass spectrometry without primary mass selection, compatible with all types of mass spectrometers, capable of simultaneously producing in a single acquisition all of all the spectra. dissociation of all the different primary masses present in a sample to be analyzed for multicharged and / or mono-charged primary ions, with dissociation of the parent primary ions at low kinetic energy. For this purpose, a tandem flight time mass spectrometry method comprising the following steps is proposed according to the invention: a source of primary ions to be analyzed is provided; a primary mass spectrum of the ions is generated; non-dissociating primers, this spectrum containing peaks of occurrences of primary ions, - from this spectrum, it is determined for each of the primary mass peaks that it contains the value of the function depending on the mass-to-charge ratio of the ions The primary data of the mass spectrometer used, corresponding to the maximum number of occurrences of this peak, and the electric charge of the primary ions, - from these data, correlation laws are determined in the form of linear equations of each of the peaks. of primary mass, giving all possible pairs, and trios, of values of the mass-to-charge ratio function of dissociated charged fragments of the mass spectrometer used, corresponding to m axima of occurrences of pairs, and trios, possible of dissociation mass peaks produced by pairs, and trios, of charged mass-to-charge ratio fragments likely to come from the dissociation of identical primary ions having the same ratio charge mass, - primary ions are dissociated without selection of primary mass at low kinetic energy, so as to obtain for each of them, a pair, or a trio, charged fragments, - one generates a dissociation spectrum without selecting the primary mass containing the dissociation mass peaks of each of the dissociation spectra corresponding to each primary mass peak, - from this spectrum, for each of the dissociation mass peaks that it contains, each value of the function of the mass-to-charge ratio of the dissociated charged fragments of the mass spectrometer used corresponding to the maximum of occurrences of this peak, - one generates from the values my ureas of the function of the mass-to-charge ratio of the dissociated charged fragments of the mass spectrometer used corresponding to the maxima of occurrences of the dissociation peaks all the pairs, and all the trios, potentials of these values, - one identifies, among said pairs and potential trios, the actual pairs and trios that satisfy a proximity criterion with respect to the correlation laws, and thereby identifying the pairs, and the trios, of dissociation mass peaks corresponding to the same peak of the primary mass spectrum each dissociation spectrum corresponding to each of the primary mass peaks is produced, with the pairs, and the trios, of dissociation mass peaks corresponding to the actual identified pairs and trios. Preferred but non-limiting aspects of this method are the following: * the dissociated charged fragment pairs are derived from the low kinetic energy dissociation of multicharged primary ions, and the trios dissociation of fragments each containing a pair of charged fragments and a neutral fragment of known mass. the dissociated charged fragment pairs are derived from the dissociation at low kinetic energy of multicharged and / or mono-charged primary ions dissociating into pairs of neutral and charged fragments, with ionization of the dissociated neutral fragments. the trios of dissociated charged fragments result from the dissociation at low kinetic energy of multicharged primary ions, and from the dissociation into trios of fragments each consisting of either a pair of charged fragments and a neutral fragment of any mass or a pair of neutral fragments of any mass to a charged fragment, with ionization of the dissociated neutral fragments.

  Another object of the invention is to propose a tandem mass spectrometer comprising, according to the general direction of movement of the ions: an ion source (1), means for forming a primary mass spectrum of these ions; primary ions from these ionized molecules, so as to be able to identify the value of the mass-to-charge ratio function of the primary ions of the mass spectrometer used corresponding to the maximum number of occurrences and the primary electric charge, corresponding to each mass peak primary of these ions, - a device for dissociating (2) the primary ions so as to obtain, for each of them, a pair, or a trio, of charged fragments, - a mass spectrometer (3), producing the spectrum primary mass of the primary ions, and the dissociation spectrum without primary mass selection of the charged fragments, - an ion detector (4), - identification means, in the set of dissociation mass peaks, of the pairs, and trios, of dissociation mass peaks corresponding to pairs, and trios, charged fragments resulting from the dissociation of primary ion parents of the same mass-to-charge ratio, these identification means being arranged so that the identification is based on the measured values of the mass-to-charge ratio function of the dissociated charged fragments of the mass spectrometer used corresponding to the maxima of occurrences of the dissociation mass peaks, and of predetermined correlation laws, giving the pairs, and trios, possible of these values.

  Another object of the invention is to propose a tandem mass spectrometer comprising, according to the direction of general displacement of the ions: an ion source (1), means for supplying a primary mass spectrum of these ions primary ions io from these ionized molecules, so as to be able to identify the value of the function of the mass-to-charge ratio of the primary ions of the mass spectrometer used corresponding to the maximum number of occurrences and the primary electrical charge corresponding to each primary mass peak of these ions, - a device (5) for injecting into the dissociation device (2), only the primary ions from the primary mass peaks of the molecules of interest, - a device for dissociating the primary ions in pairs, and in trios, charged fragments (2), -a mass spectrometer (3), producing the primary mass spectrum of the primary ions, and the dissociation spectrum without primary mass selection of the 20 charged elements, an ion detector (4), identification means, in the set of dissociation mass peaks, pairs, and trios, of dissociation mass peaks corresponding to pairs, and trios, charged fragments resulting from the dissociation of parent primary ions of the same mass-to-charge ratio, these identification means being arranged so that the identification is based on the measured values of the mass-to-charge ratio function of the dissociated charged fragments of the mass spectrometer used corresponding to the maxima of occurrences of the dissociation mass peaks, and of predetermined correlation laws, giving the possible pairs, and triples, of these values.

  Preferred but non-limiting aspects of these tandem mass spectrometers are the following: the source of primary ions (1) is a source of multicharged ions and / or mono charged ions, the dissociation device (2) ) Primary ions in pairs, and in trios, charged fragments is equipped with a system ionizing the neutral fragments from the dissociation at low kinetic energy of the primary ions. Preferred, but not limiting, aspects of this tandem mass spectrometer are the following: the device (5) for simultaneously selecting the primary mass peaks of interest is an ion trap, - the ion trap (5) allows the dissociation spectra to be produced in (MSn) mode, by performing the following steps: by selecting primary ions, or dissociated charged fragments, of the same mass-to-charge ratio with the mass selection mode of the ion trap (5), by dissociating, in the ion trap (5), the primary ions or the dissociated charged fragments selected, in a first dissociation step, into dissociated charged fragments, by collision with the molecules of a gas, then * injecting, in a second dissociation step without primary mass selection, the dissociated charged fragments produced in the dissociation device (2) where they are again fragmented, and * e n ionizing the neutral fragments dissociated with the ionization system of the neutral fragments of the dissociation device (2), to produce the pairs and trios of charged fragments, by introducing said pairs and trios of dissociated fragments into the mass spectrometer (3) to produce the dissociation spectrum without primary mass selection of the dissociated charged fragments in the first dissociation step.

  Preferred but non-limiting aspects of these tandem mass spectrometers are as follows: the device for dissociation (2) of the primary ions in pairs, and in trios, of charged fragments at low kinetic energy is a multipolar waveguide containing gas dissociating the primary ions by multiple collisions with the gas molecules, - the multipolar waveguide is equipped with a system ionizing the neutral fragments from the low kinetic energy dissociation of the primary ions in the waveguide multipolar (2). The object of the invention is also to propose a computer program that can be implemented in a tandem flight time mass spectrometry system and comprises a set of instructions able to perform the following steps: controls the system to generate, from a source of primary ions to be analyzed, a primary mass spectrum of these primary ions, without dissociation, this spectrum containing peaks of occurrences of primary ions, - performs an acquisition of the data of this spectrum, - from said data, it is determined for each of the primary mass peaks that it contains the value of the function of the mass-to-charge ratio of the primary ions 20 of the mass spectrometer used, corresponding to the maximum of occurrences of this peak, and the electric charge of the primary ions, - from these data of peaks, one determines correlation laws giving all the pairs, and the trios, possible of values of the functio n of the mass-to-charge ratio of dissociated charged fragments of the mass spectrometer used corresponding to maxima of occurrences of pairs, and trios, possible of dissociation mass peaks produced by pairs, and trios, of charged fragments from different primary ions, - the system is controlled so that it generates the dissociation of the primary ions at low kinetic energy so as to obtain for each of them, a pair, or a trio, of charged fragments, - one generates, without primary mass selection, a dissociation spectrum of these dissociated charged fragments containing the dissociation mass peaks of each of the dissociation spectra corresponding to each primary mass peak, - from this spectrum, it is determined for each of the peaks of dissociation mass that it contains each value of the function of the mass-to-charge ratio of the dissociated charged fragments of the mass spectrometer used corresponding to the maximum of occurrences of this peak, - one generates from the values measured all the pairs, and trios, potentials of these values, - one identifies, among said pairs, and trios, potentials, the pairs, and the trios, real which satisfy a criterion of proximity with respect to the correlation laws, and thus identify the pairs, and the trios, of dissociation mass peaks corresponding to the same peak of the primary mass spectrum, - each dissociation spectrum corresponding to each primary mass peaks, with pairs, and trios, of dissociation mass peaks corresponding to identified pairs, and trios, real. BRIEF DESCRIPTION OF THE FIGURES Other aspects, objects and advantages of the invention will appear better on reading the following description of the invention, given by way of nonlimiting example, and with reference to the appended drawings in which: FIG. 1 is a flowchart of a preferred embodiment of the spectrometry method according to the invention, FIG. 2 illustrates components of a system capable of implementing the mass spectrometry method according to an example of FIG. FIG. 3 illustrates a primary mass spectrum of molecules to be identified, having three primary mass peaks; FIG. 4 illustrates a dissociation mass spectrum obtained without primary mass selection, including mass peaks; of the three dissociation spectra of the three primary mass peaks of the primary mass spectrum example of FIG. 3, with some of the measured values Finax (m / q) of the mass ratio function on charge of the dissociated charged fragments of the mass spectrometer used, corresponding to the maximum of occurrence of each peak of dissociation mass, - Figure 5 illustrates the three dissociation spectra of the three primary mass peaks of Figure 3, obtained with the according to the invention, from the dissociation spectrum without primary mass selection of FIG. 4, FIG. 6 illustrates in the plane {Fx (mr / gr •), Fx (ms / gs ^)} of the two-dimensional spectrum. , three examples of characteristic lines of multicharged primary ions dissociating into pairs of charged fragments, corresponding to the correlation laws of three primary mass peaks, each primary mass peak corresponding to a different primary charge (Q'1 = 2 e, Q'2 = 3 e and Q'3 = 4 e, where e is the unit of electric charge), - Figure 7 illustrates the plane {Finax (mr / gr>), F ,,, ax (ms / qs ')} of a two-dimensional spectrum comprising only three corresponding characteristic lines three double charged primary ion mass peaks of Figure 3, dissociating without primary mass selection into charged fragment pairs. Positions in the {Finax (mr / gr •), Finax (ms / qs')} plane of the two-dimensional spectrum of potential and actual pairs of mass-to-charge ratio function values of the dissociated charged fragments of the corresponding mass spectrometer used at the maximum occurrences of the dissociation peaks of FIG. 4 are also shown in the figure; FIG. 8 illustrates a tandem mass spectrometer according to one embodiment of the invention, with a device (5) positioned between the ion source (1) and the dissociation device (2) for selecting and injecting into the dissociation device (2) the primary ions from the primary mass peaks of the molecules of interest.

  DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION It is recalled as a preliminary that the term multi-charged ion is understood to mean an ion having a positive or negative electric charge of absolute value greater than or equal to 2 e (where e is the unit of electric charge ). With reference to FIG. 1 in particular, the method according to the invention aims to dissociate the multicharged primary ions into pairs of charged fragments, into trios of charged fragments, and into trios of fragments with a pair of charged fragments and a neutral fragment of known mass. It also aims to dissociate the multicharged primary ions into neutral and charged fragment pairs, and into trios of fragments containing either a pair of charged fragments and a neutral fragment of any mass, or a pair of neutral fragments of any mass and a fragment. charged, using the same dissociation channels with ionization of dissociated neutral fragments, to produce pairs and trios of charged fragments. With reference also to FIG. 1, the method according to the invention aims at the dissociation of the mono-charged primary ions in pairs of neutral and mono charged fragments, by using the same dissociation channel with ionization of the dissociated neutral fragment, to produce pairs loaded fragments.

  In the present embodiment, we first provide a primary mass spectrum of primary ions from molecules that are to be identified without dissociation. This primary mass spectrum can be obtained by reading from a database, such as a third-party database, in which it has previously been saved. It can also be obtained by carrying out steps (a) and (b) illustrated in FIG. 1. In step (a) of this figure, the molecules to be identified are ionized in an ion source, represented on FIG. Figure 2 by the reference (1), and accelerates with a generally constant electric field. Then in step (b), the primary ions are injected into the mass spectrometer used (3), and then measured as a function of the variation of the function F (M / Q) of the mass spectrometer used (3). , the occurrences (or the intensity of the ion current) of the primary ions detected by the ion detector (4). The function F (M / Q) is of the form: F (M / Q) = G x (M / Q), where G is a function which depends on the mass spectrometer used (3) independent of the mass-to-charge ratio of ions, and M / Q is the mass-to-charge ratio of the primary ions. The primary mass spectrum (MS) is then produced based on these measurements.

  According to the usual graphical presentation in mass spectrometry, conventionally used by those skilled in the art (but not limited to), the primary mass spectrum is generally represented with two perpendicular axes, with the measured values of the function F on the abscissa (M / Q), and ordinate the occurrences (or intensity of the detected ion current) corresponding.

  This primary mass spectrum then makes it possible to determine, in a step (c), the value Finax (M / Q) of the mass-to-charge ratio function of the primary ions of the mass spectrometer used corresponding to the maximum number of occurrences and the load primary electric Q primary ions, corresponding to each primary mass peak.

  Those skilled in the art can determine the charge Q for multicharged primary ions corresponding to each primary mass peak with the identification techniques usually used in mass spectrometry. In addition, it will be able to determine the values of each primary charge mass ratio (M / Q) of the primary ions corresponding to each primary mass peak, by performing the usual preliminary primary calibration of the mass spectrometer used, with known molecules. FIG. 3 shows an example of a primary mass spectrum containing three primary mass peaks of primary ions, respectively of mass-to-charge ratio, (M1 / Q1), (M2 / Q2), and (M3 / Q3), with the Finax values (M / Q) of the mass-to-charge ratio function of the primary ions of the mass spectrometer used corresponding to the maximum of occurrences of each of these primary mass peaks.

  In a step (d), determined from these data, the so-called correlation laws of each of the primary mass peaks, giving all the possible pairs {Finax (mi / gi '), Finax (mi / qi ,)), and all possible trios {Finax (mi / qi,), Fmx (mi / q '), Finax (mk / qk')}, values of the mass-to-charge ratio function of dissociated charged fragments of the spectrometer of mass used, corresponding to maxima of occurrences of pairs, and trios, possible of dissociation mass peaks produced by pairs, and trios, possible of dissociated charged fragments of mass-to-charge ratios {(mi / gi, ), (mi / qj ')}, and {(mi / gi), (mi / qj'), {(mk / qk ')}), likely to come from the dissociation of identical primary ions of the same ratio mass on load (M / Q). The relationship between the primary mass M and the possible mass pairs of the charged fragments (mi, mi) is: M = mi + mi.

  In the case of multicharged primary ions that dissociate directly into pairs of charged fragments, the relationship between the primary charge Q and the possible charge pairs of the charged fragments (gi, gi) is: Q = qi '+ qi' In the case multicharged primary ions dissociating into pairs of neutral fragments and charged with ionization of the neutral fragments we have: Q + e = qi, + q. In the case of mono-charged primary ions dissociating in pairs of neutral and mono charged fragments with ionization of neutral fragments we have: Q = qi, = qi> = e. The number of correlation laws per primary mass peak is equal to the number of electrical charge distribution possibilities between the dissociated charged fragment pairs. In the case of mono-charged primary ions dissociating into pairs of neutral and mono-charged fragments with ionization of the neutral fragments, there is only one possibility of possible charge distribution between the dissociated charged fragment pairs, namely: , = e and qi, = e, and therefore a single corresponding correlation law giving all the possible pairs of mass of charged fragments (mi, mj). For multicharged ions that dissociate directly into pairs of charged fragments, with Q = 2 e, there is also only one possibility of possible charge distribution between the separated charged fragment pairs: qi '= e, qi' = e, and therefore also a single corresponding correlation law. For Q = 3 e, there are two possible load distribution possibilities between the charged fragment pairs: (qk '= e, qi' = 2 e), and (qk '= 2 e, qi' = e), and therefore two corresponding correlation laws. For Q = 4 e, there are three possible load distribution possibilities between the charged fragment pairs (qi '= e, qi' = 3e), (qi '= 3e, gi' = e), and (qi ' = 2e, gi '_ 2e), and thus three corresponding correlation laws. And so on. In the case of multicharged primary ions dissociating into neutral fragment pairs and ion-loaded with neutral moieties, the ionized neutral moiety may be only mono charged. So there are only two possibilities of distribution of loads whatever the initial primary load: (qi '= e, qj' = 2 e), and (qi> = 2 e, qj '= e), and thus two corresponding correlation laws. With the dissociation of the primary ions at low kinetic energy, the function F (m / q) of the mass spectrometer used (3) is of the form: {F (m / q) = G x (m / q), where G is a function that depends on the mass spectrometer used independent of the mass-to-charge ratio of the ions, and m / q is the mass-to-charge ratio of the dissociated charged fragments. Each of the correlation laws corresponding to each pair of charges (qi>, qj ') of each of the primary mass peaks corresponding to primary ions of the same mass-to-charge ratio (M / Q), dissociating into charged fragment pairs can then always write in the form of a linear equation from the equation {1}: Finax (mi / qi ') = Finax (M / qi') ù (qi '/ qi') Finax (mj / qj '), with Finax (M / gi') = (Q / fold) F x (M / Q) • Each correlation laws of each primary mass peak corresponding to each charge pair of the dissociated fragments (gi> , qj '), can therefore be determined by the method according to the invention simply with the values of the primary charge Q and the function Fmax (M / Q) corresponding to the maximum occurrence of said primary mass peak. the determination of the primary charge Q of each primary mass peak in the preceding step makes it possible to determine each possible charge pair (qi ', q;') of each correlation law elation of this primary mass peak for each possible dissociation channel. The determination of the flight time of the maximum occurrence Finax (M / Q) and the primary charge Q of each primary mass peak in the previous step also makes it possible to determine each value F (M / gi ') of each correlation law corresponding to this primary mass peak by: F (M / gi ') = (Q / qi') Finax (M / Q) • In the case of dissociated charged fragment pairs from a trio of fragments also containing a neutral fragment, one can determine the corresponding correlation laws if the mass of the neutral fragment is known. Generally, a large part of the various possible masses of the dissociated neutral moiety in this dissociation channel is known to those skilled in the art. For example, in the case of peptides, the neutral moieties are often the following molecules: H2O, CO, NH3, and other possible molecules can be determined with the databases, or are known to those skilled in the art. If AM is the mass of the known possible neutral moiety, each correlation law of the dissociation channels in charged fragment pairs with a known mass neutral fragment corresponding to each possible AM value is determined from the previous correlation laws obtained. for the cleavage channels in pairs of charged fragments for primary ions of mass M and charge Q, replacing M by (M-AM) with: Furax (mi / qi ') = Furax {(M-AM) / qi } (qj '/ qi') Furax (mj / qj '), with: Furax ((M-AM) / qi')} = (Q / q ') Fmax {(M ûAM) / Q)} .

  In the case of multicharged ions of mass M of primary charge Q greater than or equal to 3e, dissociating into a trio of fragments loaded with mass-to-charge ratios {(mi / qi '), (mi / qj'), {(mk / qk ')}, with: mi + mi + mk = Metgi' + q '+ qk' = Q, we can also determine each correlation law corresponding to each load distribution possibility of the three dissociated charged fragments (gi ', gj ', qk') from equation (11, as in the case of charged fragment pairs, with the linear equation: Furax (mi / qj ') = Furax (M / qi') ù (qj ') / qi ') Fmax (mi / qj') ù (qk '/ qi') Furax (mk / qk '), 10 with: Finax (M / qi') = (Q / qi ') Finax (M / Q) The number of correlation laws per primary mass peak is equal to the number of possibilities of distribution of the electric charge between the trios of dissociated charged fragments, for example in the case of primary ions multi charged with charge Q = 3e. , there is also only one possibility of distribution of loads in ssible between the pairs of dissociated charged fragments: qi '= qj' = qk, = e, and thus also a single corresponding correlation law. And so on for primary charges Q greater than 3 e. The case of the multicharged ion dissociation channels, with ionization of the dissociated neutral fragments, in trios of fragments initially containing either a pair of charged fragments and a neutral fragment, or a pair of neutral fragments and a charged fragment, are similar, for the production of the laws of correlations, in the previously described case of the dissociation in trios of charged fragments. It suffices to replace the primary charge Q by Q + e in the case of an initial trio containing a pair of charged fragments and a neutral fragment, and the primary charge Q by Q + 2 e in the case of an initial trio containing a pair of neutral fragments and a charged fragment, in the preceding equations. The charged fragments coming from the ionization of the neutral fragments will be only mono charged. In step (e), primary ions of low kinetic energy are dissociated (2) so as to obtain, for each of them, a pair or a trio of charged fragments.

  Then in step (f), the dissociated charged fragments are injected into the mass spectrometer (3), and then measured as a function of the variation of the function F (m / q) of the form of equation (11). mass spectrometer used (3) the occurrences (or the intensity of the ion current), dissociated charged fragments detected by the ion detector (4). Then, on the basis of these measurements, without primary mass selection, the dissociation mass spectrum (MS-MS) containing all the dissociation mass peaks of each of the parent primary ion dissociation spectra of each peak of primary mass of the primary mass spectrum. The dissociation mass peaks of the different dissociation spectra corresponding to the different primary mass peaks are therefore mixed in the dissociation spectrum produced without primary mass selection. According to the usual graphical presentation in mass spectrometry, conventionally used by those skilled in the art (but not limiting), the dissociation mass spectrum (MS-MS) obtained is generally represented with two perpendicular axes, with the abscissa values measured from the function F (m / q), and ordinate the corresponding occurrences. FIG. 4 shows by way of illustration and non-limiting example and to simplify the description, a dissociation spectrum (MS-MS) containing the dissociation peaks corresponding only to the charged pair-pair dissociation channel, of the three primary mass peaks of the example of Figure 3. It is understood that in reality, the dissociation of the primary ions produces charged fragments from other possible channels of dissociation of interests identifiable by the method according to the invention (such as for example, in the case of multicharged primary ions without ionization of the neutral fragments, trios dissociations of charged fragments and trios containing a charged fragment pair and a known mass neutral fragment), and dissociation peaks which are not not identifiable by the process according to the invention (such as, for example, in the case of multicharged primary ions without ionization of the dissociated neutral fragments, the pi dissociation cs corresponding to dissociations in pairs of neutral and charged fragments).

  The multicharged ion sources also generally produce mono-charged primary ions which can dissociate into pairs of neutral and mono-charged fragments, which will produce, without ionization of the dissociated neutral fragments, mass peaks which will not be identified by the method according to the invention.

  The dissociation spectrum obtained without primary mass selection will thus also contain, in addition to identifiable interest dissociation mass peaks, dissociation mass peaks corresponding to the other possible unidentifiable dissociation channels, as well as the primary mass peaks. non-dissociated multi-charged and / or mono-charged primary ions. But the dissociation peaks other than the identifiable interest dissociation peaks, and primary mass peaks are eliminated from the dissociation spectra produced by the method according to the invention. It can be seen in the example of FIG. 4 that the dissociation spectrum comprises fourteen dissociation mass peaks corresponding to seven pairs of dissociation peaks, each peak dissociation pair being produced by pairs of charged fragments originating from the dissociation of identical primary ions having the same mass-to-charge ratio. In step (g), each Finax value (m / q) of the function of the mass-to-charge ratio of the dissociated charged fragments of the mass spectrometer used corresponding to the maximum of occurrences of each of the dissociation peaks of the dissociation spectrum is determined. obtained without primary mass selection. Four of the Finax values (m / q) of the function of the mass-to-charge ratio of the dissociated charged fragments of the mass spectrometer used corresponding to the maxima of occurrences of four peaks of the earth, can also be seen in the example of FIG. dissociation among the fourteen different dissociation peaks represented. In step (h), all the potential pairs {Finax (mr / gr '), Finax (ms / qs')}, and all the potential trios {Fmax (mr / gr'), Finax (ms / them '), Finax (m, / qv')}, of these values.

  In step (i), we identify among the set of potential pairs {Finax (mr / gr '), Finax (ms / qs')}, and potential trios {Fmax (mr / qr -'), Finax (ms / gs'), Finax (m ,, / qa ')}, the real pairs {Finax (mt / gt), Finax (mu / qu)}, and the real trios {Finax (mt / qt'), Finax (mu / qu '), Finax (mw / qw')} corresponding to the pairs, and trios, actual dissociation peaks produced by pairs, and trios, of dissociated charged fragments from the dissociation of primary ions identical with the same mass-to-charge ratio for each of the primary mass peaks, comparing the potential pairs and trios with the possible pairs (Fmax (mi / qi '), Fmax (mj / cu •)}, and the possible trios {Finax (mi / qi '), Finax (mi / qj), Finax (mk / qk')}, determined by the correlation laws of each of the primary mass peaks. According to the invention, this identification step consists in selecting from the pairs and the potential trios those which satisfy a criterion of proximity with respect to the possible pairs and trios provided by said correlation laws of each of the primary mass peaks.

  This criterion of proximity is at least, in the order of the precision of the measurement of the Finax values (MIQ) of the mass-to-charge ratio function of the primary ions of the mass spectrometer used corresponding to the maximum of occurrences of the different peaks of primary mass and which determines the accuracy of the corresponding correlation laws, and of the order of the accuracy of the measurements of the Fmax (m / q) values of the mass-to-charge ratio function of the dissociated charged fragments of the mass spectrometer used corresponding to the maxima of occurrences of the different peaks of mass dissociation and which determines the precision of the values of the pairs and trios, potential and real. The accuracy of Finax values (MIQ) and Finax values (m / q) is essentially dependent on the resolution of the corresponding mass peaks. Without ionization of the dissociated neutral fragments, step (i) makes it possible to identify the dissociation peaks for multicharged primary ions corresponding to the dissociation channels in pairs of charged fragments, in trios of fragments containing a pair of charged fragments and a fragment known mass neutral, and in trios of charged fragments.

  With ionization of the dissociated neutral fragments, step (i) also makes it possible to identify the dissociation peaks for mono-charged primary ions dissociating in pairs of neutral and mono charged fragments, and for multicharged primary ions the corresponding dissociation peaks. to the neutral and charged fragment-pair dissociation channels, in trios of fragments containing a pair of charged fragments and a neutral fragment of any mass, and in trios of fragments containing a pair of neutral fragments of any mass and a charged fragment. Finally, in each step (j), each dissociation mass spectrum corresponding to each of the primary mass peaks is generated with the actual pairs, and trios, of identified dissociation mass peaks. According to the usual graphical presentation in mass spectrometry conventionally used by those skilled in the art (but not limited to), each dissociation mass spectrum is generally represented with two perpendicular axes, with the values of the function F (m / m) being the abscissa. q) measured, and ordinate the corresponding occurrences. FIG. 5 illustrates, by way of nonlimiting example, the three dissociation spectra of the three primary mass peaks of FIG. 3, obtained with the method according to the invention, from the dissociation spectrum without primary mass selection. of FIG. 4, after the identification of pairs and trios of dissociation mass peaks with the method according to the invention. Without ionization of the dissociated neutral fragments, each dissociation spectrum containing the dissociation peaks for multicharged primary ions corresponding to the dissociation channels in pairs of charged fragments is produced in step (j), in trios of fragments containing a pair of charged fragments and a neutral fragment of known mass, and in trios of charged fragments. With ionization of the dissociated neutral fragments, in step (j) each dissociation spectrum also containing the dissociation peaks for multicharged primary ions corresponding to the neutral and charged fragment pair dissociation channels and in trios of fragments is produced. containing a pair of charged fragments and a neutral fragment of any mass, and trios of fragments containing a pair of neutral fragments of any mass and a charged fragment. With the ionization of the dissociated neutral fragments, each dissociation spectrum containing the dissociation peaks for mono-charged primary ions corresponding to the dissociation channel in pairs of neutral and mono charged fragments is also produced in step (j). In order to explain step (i) mentioned above, we will now describe its preferred embodiment by reasoning on a graphical representation in the case of dissociation channels in pairs of charged fragments.

  Those skilled in the art will nevertheless understand that this is only one type of representation among others, intended primarily to illustrate the principles of this step and to understand how the digital processing of the invention 'conduct. Step (i) of the method according to the invention is carried out with the following sub-steps: Firstly, one of the set of potential pairs {Finax (mr / gr '), Finax (ms / qs')) is identified. }, each real pair {Finax (mt / gt), Finax (mu / qu)} starting by generating, according to a step (i 1), a two-dimensional spectrum. This spectrum has two identical dimensions each representing the measured values of the mass-to-charge ratio function of the dissociated charged fragments of the mass spectrometer used corresponding to the maximums of occurrences of dissociation mass peaks of the dissociation spectrum obtained without selection. primary mass. Graphically, the two dimensions correspond to two axes which are preferably perpendicular to each other.

  In the plane {Finax (mr / gr '), Finax (ms / gs')} of the two-dimensional spectrum, each correlation law is represented by a correlation characteristic line whose position, according to a step (i2), in the plane above is determined by the linear equation: limai (mi / qi ') = Finax (M / gi') where Finax (mi / ce), with: Finax (M / qi ') = (Q / qi') Finax ( MIQ) • One can then determine graphically in the plane {Finax (mr / gr '), Finax (ms / qs')} of the two-dimensional spectrum each characteristic line of correlation with the values of each pair {Finax (M / gi') , Finax (M / gj ')}. Each pair {Finax (M / gi '), Finax (M / gj')} are the two points on each of the 5 two axes of the plane {Finax (mr / gr '), Finax (ms / qs')} of the spectrum two-dimensional (Finax (M / gi ') on the Finax axis (mr / gr'), and Finax (M / gj ') on the Finax axis (ms / qs')), of the equation characteristic line: Furax (mi / qi ') = Furax (M / qi') ù (qi '/ qi') Furax (mj / qj '). Thus each correlation characteristic line 10 is simply determined in the plane {Finax (mr / gr '), Finax (ms / qs')} of the two-dimensional spectrum corresponding to each correlation law by connecting the two points Finax (M / gi' ), and Fi ,, ax (M / gi ') located on both axes of the two-dimensional spectrum. The values of each pair {Finax (M / gi '), Finax (M / gj')} of each correlation characteristic line corresponding to each pair of charge (gi ', gj') are determined with the value Fn, ax (M / Q) of the mass-charge ratio function of the primary ions of the mass spectrometer used corresponding to the maximum number of occurrences and the primary charge Q, of the corresponding primary mass peak with: F. (M / qi ') = (Q / qi ') Finax (M / Q) and Furax (M / gi') = (Q / q ') Finax (M / Q • Figure 6 shows, by way of non-limiting example, the straight lines correlation characteristics in the plane {Finax (mr / gr '), Finax (ms / gs')} of the two-dimensional spectrum, determined by the correlation laws corresponding to three primary mass peaks of rnulticharged primary ions dissociating directly in pairs loaded fragments, respectively of primary charge Q'1 = 2 e, Q'2 = 3 e, and Q'3 = 4 e.The equation of the characteristic line in the plane {Finax (mr / gr '), Fmax (ms / qs')} of the show FIG. 6 is a two-dimensional map corresponding to the correlation law of the primary primary electric charge peak Q '1 = 2 e is: Furax (mile) = Furax (M' 1 / e) Furax (mile). The equations of the two characteristic lines in the plane Fmax (mr / gr '), Finax (ms / gs')} of the two-dimensional spectrum of FIG. 6 corresponding to the two correlation laws of the primary mass peak of primary electric charge Q '2 = 3 are: Fmax (mile) = Fmax (M'2 / e) ù 2 Fmax (mid / 2nd), and Fmax (mid / 2nd) = Finax (M'2 / 2e) ù (1/2) Fmax (mile). The equations of the three characteristic lines in the plane {Finax (mr / gr '), Finax (ms / qs>)) of the two-dimensional spectrum of FIG. 6 corresponding to the three correlation laws of the primary mass peak of primary electric charge Q' 3 = 4 are: Fmax (mile) = Fmax (M3 / e) ù 3 Finax (mid / 3rd), Fmax (mid / 3rd) = Fmax (M3 / 3rd) ù (1/3) Fmax (mile) ), and Finax (mi / 2e) = Finax (M'3 / 2e) to Finax (mi / 2e). We associate in a step (i3) to each potential pair {Finax (mr / gr)), Finax (ins / qs')} a position of occurrence Prs corresponding in the two-dimensional spectrum. To each potential pair {Finax (mr / qr), Finax (ms / qs>)} corresponds to a symmetric potential pair {Finax (ms / gs>), Finax (mr / qr ')}. To these two symmetrical potential pairs therefore correspond a pair of positions of symmetrical different occurrences (Prs, Psr) in the plane {Finax (mr / gr '), Finax (rns / qs')} of the two-dimensional spectrum. We identify, in a step (i4), each real pair {Finax (mt / gt), Finax (mu / qa)} among the potential pairs {Finax (mr / gr>), Finax (ms / gs')}, retaining those whose corresponding pair of occurrence positions (Ptu, Put) in the two-dimensional spectrum are each at a distance from one of the determined characteristic lines, less than a given threshold. The value of this distance threshold is at least of the order of the accuracy of the measurements of the values Fmax (M / Q) which determine the accuracy of the corresponding characteristic lines, and of the order of the precision of the measurements of the values Fmax. (mlq) that determine the accuracy of the positions of potential and actual occurrences in the two-dimensional spectrum.

  FIG. 7 shows, by way of nonlimiting example, a plane {Finax (mr / gr '), Finax (: ms / qs')} of two-dimensional spectrum in which the three characteristic lines corresponding to the correlation laws of three peaks are positioned. of primary masses of doubly charged primary ions directly dissociating into pairs of mono fragments loaded respectively with mass-to-charge ratios (M1 / Q1), (M2 / Q2), and (M3 / Q3) (with Q1 = Q2 = Q3) = 2 e), the primary mass spectrum example of Figure 3. It can also be seen in this non-limiting example, and to simplify the description, that only four values, {Fmax (ml / gl), Finax (m4 / g4)} and to {Finax (m2 / g2), F ,,, ax (m3 / q3)}, corresponding to two real pairs of dissociation peaks among the fourteen of figure 4, are represented. These four Finax values (m / q) will produce sixteen positions of different occurrences Prs corresponding to the potential pairs in the plane {F x (mr / gr •), Fmax (ms / gs>)} of the two-dimensional spectrum of FIG. which are represented by crosses. In the case where the fourteen Finax values (m / q) corresponding to the fourteen dissociation peaks of FIG. 4 would be represented in FIG. 7, 196 potential occurrence positions would be determined. The two pairs of actual occurrence positions to be identified (P14, P41) and 20 (P23, P32) are shown in Figure 7 by crosses surrounded by a circle. It can be seen that the pair of positions of potential occurrences closest to the characteristic line corresponding to primary ions of mass-to-charge ratio (M1 / Q1) is the pair (P14, P41). Indeed, these positions are located on or in the immediate vicinity of this characteristic line. The pair {Fraax (mi / gi), Fmax (m4 / q4)} corresponding to the pair of positions (P14, P41) is therefore identified as that of a pair of dissociation peaks belonging to the dissociation spectrum of the peak of mass primary mass-on-load (Ml / Q1) of the example of Figure 3.30 On the contrary the other pairs of potential positions are away from this characteristic line by a distance greater than the chosen threshold, so that we consider they do not come from pairs of dissociation peaks belonging to the dissociation spectrum of the primary mass peak of charge mass ratio (M1 / Q1). It is likewise noted that the pair of positions of potential occurrences closest to the characteristic line corresponding to primary ions of mass to charge ratio (M2 / Q2) is the pair of positions (P23, P32). The pair {Finax (m2 / g2), Finax (m3 / q 3)} corresponding to the pair of positions (P23, P32) is therefore identified as that of a pair of dissociation peaks belonging to the peak dissociation spectrum. The other pairs of potential positions are too far removed from the characteristic lines, with respect to the selected distance threshold criterion, so that the first pair of potential ground positions (M2 / Q2) of the FIG. it is considered that they do not arise from the dissociation of primary ions of charge mass ratio (M1 / Q1), (M2 / Q2), and (M3 / Q3). In order to avoid unnecessarily complicating the present description, the preceding example illustrated in FIGS. 4 and 7 only includes dissociation peaks of parent primary ions dissociating into pairs of charged fragments. In fact, the dissociation spectrum obtained without primary mass selection will thus also contain mass peaks corresponding to the other possible dissociation channels of the multicharged and / or mono-charged primary ions, dividing into dissociation peaks of interest that can be identified by the method according to the invention, and in non-identifiable dissociation peaks, as well as the primary mass peaks of the uncharged multicharged and / or mono-charged primary ions. The primary mass peaks of the dissociation spectrum are removed using the primary mass spectrum obtained without dissociation. The set of dissociation peaks will produce pairs, and trios, non-real potentials. These pairs, and trios, non real potentials are for the most part eliminated by the criterion of identification of the pairs, and trios, real. But some of these pairs, and trios, non-real potentials can be accepted by the criterion of identification, and produce false pairs, and trios, real identified, which will produce false pairs, and trios, of dissociation peaks in the dissociation spectra finally produced by the method according to the invention.

  Those skilled in the art will be able to eliminate these false peaks of dissociation mass with the databases by comparing the mass values of the pairs, and trios, of fragments corresponding to these false pairs, and trios, of peaks, to the masses of the pairs and trios, fragments of possible or experimental theoretical dissociation channels, for the measured mass of parent ions. The above graphical method described for the case of dissociation channels producing charged fragment pairs may also be applied to the dissociation channels producing trios of charged fragments. The preceding two-dimensional spectrum is then replaced by a three-dimensional spectrum comprising three identical axes each representing the measured values of the mass-to-charge ratio function of the dissociated charged fragments of the mass spectrometer used corresponding to the maxima of occurrences of the mass peaks. of dissociation of the dissociation spectrum obtained without selection of primary mass. Graphically, the three dimensions correspond to three axes which are preferably perpendicular to each other. The equivalent of each occurrence position Prs corresponding to each potential pair {Ftnax (mr / gr '), Finax (ms / qs')} in the preceding two-dimensional spectrum, is a position of occurrence Prsv, in the volume of the three-dimensional spectrum corresponding to each potential trio {Fmx (mr / qr '), Finax (ms / gs'), F, (mv / q ,, •>)}. To each correlation law, corresponding to the dissociation channels in trios of charged fragments, corresponds a characteristic correlation line in the volume of the three-dimensional equation spectrum: Finax (mi / ce) _. Finax (M / qi ') ù (qj' / qi ') Finax (mj / qj') ù (qk '/ qi') Finax (mk / qk '), with: Finax (M / qi') = ( Q / qi ') Fmax (M / Q). Each real trio corresponding to each position Put ,,, in the three-dimensional spectrum is identified, as in the previous two-dimensional case, among the potential trios Prsä corresponding to the positions by the proximity criterion with respect to the correlation characteristic lines.

  The method according to the invention applies to the dissociation channels of the multicharged primary ions, in pairs of charged fragments, in trios of charged fragments, and in trios of fragments with a pair of charged fragments and a neutral fragment of known mass.

  The method according to the invention can be applied to other dissociation channels for the multicharged primary ions, and also to the mono-charged primary ions, if the neutral fragments produced by the dissociation of the primary ions are also ionized. This ionization of the dissociated neutral fragments can be carried out in the ion source (1), after the fragmentation of the primary ions by ISD (acronym for In Source Decay) and before the acceleration of the ions, or in the dissociation device (2). ). However, the method according to the invention is applicable with the ionization of the dissociated neutral fragments in the ion source only in the case where a primary mass spectrum can also be produced with the same ion source (1) without dissociation. This requires two modes of operation of the ion source without and with ISD. The method according to the invention is therefore more easily achievable with a dissociation device (2) equipped with a system for ionizing dissociated neutral fragments. The ionization of the neutral fragments originating from the dissociation of the primary ions in the dissociation device (2) will make it possible to apply the method according to the invention to the mono-charged primary ions dissociating in pairs of neutral and mono-charged fragments. In the case of mono-charged primary ions, each pair of charged and neutral fragments becomes a pair of charged fragments after ionization of the neutral moiety in the dissociation device (2).

  This ionization of the neutral fragments in the dissociation device (2) will also make it possible to apply the method according to the invention to the dissociation channels of multicharged primary ions dissociating into pairs of neutral and charged fragments, and in trios of fragments comprising either a pair of charged fragment and a neutral fragment of any mass, or a pair of any mass neutral fragments and a charged fragment. In the case of the multi-charged primary ions, each pair of charged and neutral fragments becomes a pair of charged fragments after ionization of the neutral moiety in the dissociation device (2), and each trio of fragments comprising either a fragment pair In this case, a neutral fragment of any mass, either a pair of any mass neutral fragments and a charged fragment, becomes a trio of charged fragments charged to the ionization of the neutral fragments.

  The method according to the invention makes it possible to produce without primary mass selection simultaneously in a single acquisition all the dissociation spectra of all the primary mass peaks of the primary mass spectrum. The primary mass peaks of interest for which the dissociation spectrum is to be produced may represent only a portion of the total primary mass peaks. On the other hand, the higher the number of primary mass peaks, the greater the number of dissociation peaks of the dissociation spectrum produced without primary mass selection, and therefore the number of false pairs, and fake trios, actual peaks. of dissociation identified by the method is important. It is possible to use a device (5) positioned between the ion source (1) and the dissociation device (2), as shown in the example of FIG. 8, for simultaneously selecting the primary ions of the primary mass peaks. interest before their injection into the dissociation device (2), and eliminate the others. It is then possible simultaneously to produce all the dissociation of interest spectra with the method according to the invention, and to reduce the number of false pairs, and false false trios, of identified dissociation peaks. The device (5) described above may be a quadrupole mass spectrometer selecting a broad mass band containing several peaks of 25 primary masses of interest simultaneously to produce the dissociation spectrum containing the dissociation peaks to be identified from all peaks. primary mass selected. This type of device (5) makes it possible to reduce the number of false pairs, and false false trios of identified dissociation peaks, but can select only a part of the primary mass peaks of interest at each acquisition. This may require the production of several dissociation spectra with the method according to the invention to produce all of the dissociation spectra of interest.

  On the other hand. the use of an ion trap as device (5) makes it possible both to select all the primary mass peaks of interest and to reduce the number of false pairs, and false false trios of identified dissociation peaks . The ions emitted by the ion source (1) are first stored in the ion trap (5). Then, in the manner known to those skilled in the art, the stored ions are ejected out of the ion trap to the dissociation device (2) according to their mass-to-charge ratio, by applying a variable voltage in the ion trap. (5). A device consisting of, for example, a pair of deflection plates subject to a variable voltage and positioned at the exit of the ion trap (5), bypasses the ejected primary ions which are not of interest, and leaves passing only the primary ions of the primary mass peaks of interest to the dissociation device (2). The ion trap (5) also makes it possible to use the method according to the invention in the (MSn) mode for both the multi-charged and mono-charged primary ions, if the device (2) is equipped with an ionisation system. ionization of the dissociated neutral fragments, by carrying out the following steps: - primary ions, or dissociated charged fragments, of the same mass-to-charge ratio are selected with the mass selection mode of the ion trap (5), 20 - dissociates in the ion trap (5), the primary ions, or the dissociated charged fragments, selected, in a first dissociation step, into dissociated charged fragments, by collision with the molecules of a gas, and then injected into a second dissociation step without primary mass selection, the dissociated charged fragments produced in the dissociation device (2) where they are again fragmented, and ionizing the dissociated neutral fragments with the ion system isation of the neutral fragments of the dissociation device (2), to produce the pairs and trios of charged fragments, - said pairs and trios of dissociated fragments are introduced into the mass spectrometer (3) to produce the dissociation spectrum without selection primary mass of the dissociated charged fragments in the first dissociation step. The above steps can be repeated to produce the dissociation mass spectra (MS ') without primary mass selection with the method according to the invention, any dissociation mass peak (MSn-2) selected with the ion trap (5).

  The invention as described in the foregoing has been explained by a graphical approach involving a two-dimensional or three-dimensional space. However, it is understood that its concrete implementation is typically performed by a digital computer such as a DSP (Digital Signal Processor) executing the appropriate programs. In particular, the characteristic lines will typically be digital data (equations or sets of coordinates) with which the digital data produced by the spectrometers and supplied to the calculator will be compared. More concretely, the present invention can be implemented in the form of a software module in addition to an existing mass spectrometry equipment, and interfaced with the other software of this equipment so as to ensure essentially the establishment of characteristic line data and collection of measured data to confront them with characteristic line data. Those skilled in the art can analogously, if necessary, apply the method according to the invention to the case of dissociation channels producing 4 charged fragments (or more), from the previous description of the dissociation channels in trios of charged fragments. .

  Components and operation of spectrometers according to the invention

  The components and operation of a tandem mass spectrometer employing the spectrometric method according to the invention will now be described in more detail and by way of example only.

  The ion source (1) can be continuous or pulsed. It can be one of the following ion sources or any other type of multicharged and / or mono-charged ion source: a source of ESI electrospray multi-charged ions (acronym for "Electro-Spray Ionisation"), a source of pulsed laser ions MALDI (acronym for "Matrix Assisted Laser Desorption Ionization"), a source of ionic ions with atmospheric pressure ionization APCI (acronym for "Atmospheric Pressure Chemical Ionisation"), a source of ions with photoionization APPI (acronym for "Atmospheric Pressure Photo Ionization"), a laser desorption and ionization ion source LDI (acronym for "Laser Desorption Ionization"), an inductively coupled plasma ion source ICP (acronym Inductively Coupled Plasma), an electron impact ion source EI (acronym for "Electron Impact"), a CI ionization ion source (acronym for "Chemical Ionization"), an ion source for ionization by FI field (acronym e of "Field Ionization"), an ion source by bombardment of a target with a neutral atom beam FAB (acronym for "Fast Atom bombardment"), an ion source by bombarding a target with a LSIMS ion beam (acronym for "Liquid Secondary Ion Mass spectrometry"), an atmospheric pressure ionisation ion source API (acronym for "Atmospheric Pressure Ionisation"), a FI field desorption ion source (acronym of "Field Desorption"), and a source of ion desorption and ionization on DIOS silicon (acronym for "Desorption Ionization On Silicon").

  The low kinetic energy dissociation system (2) may be a multipole waveguide, an ion trap, a Fourier transform mass spectrometer, or any device for producing pairs, and trios, of fragments. loaded. The dissociation of the primary ions in pairs, and in trios, of charged fragments at low kinetic energy can be achieved by the technique of the collision induced with the molecules of an inert gas CID / CAD (acronym for "Collision Induced 30 Dissociation / Collision Activated Dissociation "), by the technique of collision with a surface SID (acronym for" Surface Induced Dissociation "), by the technique of electron capture ECD (acronym for" Electron Capture Dissociation "), by the technique of infrared photon ionization IRMPD (acronym for "Infra Red Multi Photon Dissociation"), by the high-energy photon PD technique (acronym for "Photo Dissociation"), by the high-energy photon PD technique (acronym for "Photo Dissociation "), by the heating technique BIRD (acronym for" Black Body Infra Red Dissociation "), or any other technique of fragmentation of primary ions in pairs, and in trios, of charged fragments. In the case of the dissociation of the ECD-multi-loaded primary ions (acronym for "Electron Capture Dissociation"), the electron capture producing the fragmentation modifies the charge of the primary ion Q prior to dissociation. The relation between the primary charge Q and the possible charge pairs of the charged fragments (qi>, q ') is then: Qe = qi' + qj The dissociation system (2) can be equipped with a device allowing ionizing the neutral fragments produced by the dissociation of the primary ions into neutral and charged pairs of fragments, and into trios of fragments comprising either a pair of charged fragments and a neutral fragment, or a pair of neutral fragments and a charged fragment. The device for ionizing the neutral fragments produced by the dissociation of the primary ions in pairs, and in trios, of neutral fragments and loaded into the dissociation system (2) may be: an ionization device with an electronic impact, a laser ionization device, or any other type of ionization device for ionizing neutral fragments in the dissociation system (2). The device (5) used to inject the primary ions of the primary mass peaks of interest to the dissociation device (2) can be: a quadrupole mass spectrometer, a hyperbolic geometry 3D ion trap, an ion trap Linear 2D with cylindrical geometry, or any other type of ion trap. The mass spectrometer (3) used to produce the primary mass spectrum and the dissociation spectrum without primary mass selection can be: a time-of-flight ruin spectrometer, a magnetic sector mass spectrometer, a mass spectrometer quadrupole, an ion trap, a Fourier transform mass spectrometer, or any other type of mass spectrometer. The flight time space of the time-of-flight mass spectrometer (3) between the pulsation of the ion packet and the ion detector (4) may be linear, or equipped with a reflectron. The reflectron used may be: one-stage, two-stage, curved-field CFR (acronym for "Curved Field Reflectron"), quadratic, or any other type of reflectron. The ions produced by the ion source (1) to produce each pulsation of the ion packet of the time-of-flight mass spectrometer may be previously stored in an ion trap, or by any other ion storage system. . The pulsation of each ion packet may be located in the ion source (1), between the ion source (1) and the dissociation device (2), or between the dissociation device (2) and the ion detector (4). The pulsation of the ion packet required by the time-of-flight mass spectrometer for a continuous ion source can be achieved by scanning the continuous ion beam through a slot, by a variable electric field applied between two ion plates. deflection, by the known orthogonal injection technique by applying a variable electric field between two electrodes in the direction perpendicular to the ion beam, or by any other device for pulsating a continuous ion beam. The ion trap (3) can be: a hyperbolic geometry 3D ion trap, a cylindrical geometry linear ion trap (2I), or any other type of 25 ion trap. The Fourier Transform Mass Spectrometer can be a Fourier Transform Ion Cyclotron Resonance FTICR device using to store ions, a static magnetic field, or can use a logarithmic radial electric field to store ions.

  Four non-limiting embodiments of mass spectrometers will now be described, based on the use of the components illustrated in FIG. 2 and FIG.

  First embodiment of a spectrometer

  The first embodiment of a tandem mass spectrometer according to the invention is illustrated in FIG. 2. It comprises, successively, according to the general direction of movement of the primary ions, a source of ions (1) multi-charged with electrospray ESI (acronym of "Electro-Spray Ionization"), a dissociation device (2) consisting of a multipole waveguide (q) containing gas producing, by CID (acronym for "Collision Induced Dissociation") at low kinetic energy the dissociation primary ions, an orthogonal injection-time mass spectrometer (3) with reflectron, and an ion detector (4). This tandem mass spectrometer embodiment is known to those skilled in the art who use tandem mass spectrometers with similar Qq-TOF mass selection, equipped in addition to a Q quadrupole mass spectrometer, to realize the primary mass selection in MS-MS mode.

  The first embodiment is therefore identical to these devices with the elimination of quadrupole Q. The primary mass spectrum is first produced with the orthogonal injection time-of-flight mass spectrometer, without dissociation in the waveguide. multipolar q. Then, the mass spectrum of dissociation without primary mass selection is produced also the orthogonal injection time-of-flight mass spectrometer, after the dissociation of the primary ions in pairs, and in trios, of charged fragments in the waveguide. multipole q by CID (acronym for "Collision Induced Dissociation") with low kinetic energy. The pairs and trios are identified of dissociation mass peaks of each of the dissociation spectra corresponding to each primary mass peak with the method according to the invention. Finally, each dissociation spectrum with pairs, and trios, of identified dissociation mass peaks is produced.

  In a variant of the first embodiment which has just been presented, the multipolar waveguide q used as a dissociation device (2) is equipped with a system for ionizing primary ions, for example a photoionization system. by laser.

  In another variant of the first embodiment which has just been presented, illustrated in FIG. 8, the apparatus is equipped with a quadrupole mass spectrometer (5) positioned between the ion source (1) and the device of dissociation (2), making it possible to simultaneously select, with a large mass window, several primary mass peaks of interest, and to reduce the number of false pairs, and false trios, of dissociation mass peaks identified by the method according to the invention.

  In another variant of the first embodiment which has just been presented, also illustrated in FIG. 8, the apparatus is equipped with an ion trap (5) positioned between the ion source (1) and the device dissociation circuit (2) making it possible to simultaneously select all the primary mass peaks of interest, and to reduce the number of false pairs, and false trios, of dissociation mass peaks identified by the method according to the invention.

  By combining two of the preceding variants of the first embodiment which has just been presented, also illustrated in FIG. 8, by equipping the apparatus with an ion trap (5), and equipping the dissociation device q (2). with an ionization system dissociated neutral fragments, can be used the method according to the invention mode (MSn) as described above.

  In another variant of the first embodiment which has just been presented, the ion source (1) may be preceded by a device for separating the molecules by LC liquid chromatography acronym for Liquid Chromatography.

  Second embodiment of a spectrometer

  The second embodiment of a tandem mass spectrometer according to the invention is illustrated in FIG. 2. It comprises successively, according to the direction of general movement of the primary ions, a source of ions (1) multi-charged with electrospray ESI acronym Electro-Spray Ionisation, a cylindrical geometry 2D linear ion trap (2) (3), and an ion detector (4). In this embodiment the ion trap is used both as a dissociation device (2) and as a mass spectrometer (3). This tandem mass spectrometer embodiment is known to those skilled in the art who uses identical mass spectrometers to produce primary mass selection dissociation mass spectra. The primary mass spectrum is first produced with the ion trap (2) (3) after storage of the primary ions emitted by the ion source (1), without dissociation. Then, with the ion trap, the dissociation mass spectrum is produced without primary mass selection, after the dissociation of the primary ions in pairs, or in trios, of CID-charged fragments (acronym for "Collision Induced Dissociation"). low kinetic energy with the molecules of a neutral gas in the volume of the trap. The pairs and trios are then identified with dissociation mass peaks of each of the dissociation spectra corresponding to each primary mass peak with the method according to the invention. Each dissociation spectrum is finally produced with the pairs, and the trios, of identified dissociation mass peaks.

  In a variant of the second embodiment which has just been presented, the ion source (1) may be preceded by a device for separating the molecules by LC liquid chromatography acronym for Liquid Chromatography.

  In another variant of the second embodiment which has just been presented, the linear 2D ion trap is replaced by a hyperbolic geometry 3D ion trap.

  In another variant of the second embodiment which has just been presented, the ion trap (2) (3) is equipped with a device for ionizing the neutral fragments produced by the dissociation of the ions in the trap. This device may be an electronic impact ionization system or a pulsed or continuous laser ionization system. This device will make it possible to use the method according to the invention in MS mode. After realizing the dissociation spectrum (MS-MS = MS2) without primary mass selection with the dissociation of the primary ions by CID (acronym for "Collision Induced Dissociation") at low kinetic energy, and the ionization of the dissociated neutral fragments a second dissociation spectrum (MS3) of the dissociated charged fragments can be produced. We start by storing the primary ions emitted by the ion source (1) in the ion trap (2) (3), then we select the primary ions corresponding to a single primary mass peak, eliminating the other primary ions in the manner known to those skilled in the art of primary mass selection of the ion trap (2) (3) used. The primary ions selected by CID (acronym for "Collision Induced Dissociation") are dissociated at low kinetic energy and the dissociated neutral fragments are ionized and then the charged fragments are dissociated in a second step without primary mass selection. dissociated in the first step by CID (acronym for "Collision Induced Dissociation") at low kinetic energy and ionized dissociated neutral fragments. Finally, the dissociation spectrum (MS3) of the dissociated charged fragments in the second step is produced without primary mass selection. Next, the pairs of dissociation mass peaks corresponding to each dissociation spectrum (MS3) of each peak dissociation mass peak of the selected primary mass peak are identified. Finally, each dissociation mass spectrum (MS3) is produced with pairs, and trios, of identified dissociation peaks. The foregoing steps can be repeated to produce the dissociation mass spectra (MS'1) without primary mass selection of any selected dissociation mass peak (MS -2).

  In another variant of the second embodiment which has just been presented, illustrated in FIG. 8, the apparatus is equipped with a Q quadrupole mass spectrometer (5) positioned after the ion source (1) and a dissociation device q (2), consisting of a multipolar waveguide containing gas for effecting the dissociation of the primary ions by CID at low kinetic energy, before introduction into the ion trap (3) of ions. The quadrupole Q will make it possible to simultaneously select, with a large mass window, several primary mass peaks of interest, and to reduce the number of false pairs, and false trios, of dissociation mass peaks identified by the method according to the invention. 'invention.

  In another variant of the second embodiment which has just been presented, illustrated in FIG. 8, the apparatus is equipped with an ion trap (5) positioned after the ion source (1) and a dissociation device q (2), consisting of a gas-containing multipole waveguide for effecting the dissociation of the primary ions by low kinetic energy CID, prior to introduction of primary ions into the ion trap (3) undissociated and dissociated charged fragments. The ion trap (5) will make it possible to simultaneously select all the primary mass peaks of interest, and to reduce the number of false pairs, and false trios, of dissociation mass peaks identified by the method according to the invention. .

  In another variant of the second embodiment which has just been presented, also illustrated in FIG. 8, the dissociation device q (2) of the two preceding variants may be equipped with an ionization system for the dissociated neutral fragments. .

  By combining two of the preceding variants of the second embodiment which has just been presented, also illustrated in FIG. 8, by equipping the apparatus with an ion trap (5), and equipping the dissociation device q (2). with an ionization system dissociated neutral fragments, can be used the method according to the invention mode (MSn) as described above.

  Third Embodiment of a Spectrometer The third embodiment of a tandem mass spectrometer according to the invention is illustrated in FIG. 2. It comprises, successively, according to the direction of general displacement of the primary ions, an ion source ( 1) electrospray electrospray ESI acronym for Electro-Spray Ionisation, a hyperbolic geometry 3D ion trap (2), a reflectron time-of-flight mass spectrometer (3), and an ion detector (4). In this embodiment the ion trap (2) is also used to pulse each ion packet to produce the flight time. This tandem mass spectrometer embodiment is known to those skilled in the art which uses identical mass spectrometers to produce primary mass selection dissociation mass spectra. The primary mass spectrum is first produced with the time-of-flight mass spectrometer after storage of the primary ions emitted by the ion source (1), without dissociation, and the pulsation of the ion packet towards the flight time space. Then, in a second acquisition, one dissociates without selection of primary mass by CID (acronym for "Collision Induced Dissociation") at low kinetic energy with the molecules of a neutral gas in the volume of the ion trap (2), in pairs, and in trios, of charged fragments the primary ions stored in the trap. The time-of-flight dissociation mass spectrum is then produced without primary mass selection, by pulsing the ion packet containing the dissociated charged fragments. The pairs and trios are then identified with dissociation mass peaks of each of the dissociation spectra corresponding to each primary mass peak with the method according to the invention. Each dissociation spectrum is finally produced with the pairs, and the trios, of identified dissociation mass peaks.

  In a variant of the third embodiment which has just been presented, the ion source (1) may be preceded by a device for separating the molecules by LC liquid chromatography acronym for Liquid Chromatography.

  In another variant of the third embodiment which has just been presented, the ion trap (2) is equipped with a device for ionizing the neutral fragments produced by the dissociation of the ions in the trap. This device can be an electronic impact ionization system or a pulsed or continuous laser ionization system. This device will make it possible to use the method according to the invention in MS 'mode. After realizing the dissociation spectrum (MS-MS = MSZ) without primary mass selection with the dissociation of the primary ions by CID (acronym for "Collision Induced Dissociation") at low kinetic energy and the ionization of the dissociated neutral fragments, a second dissociation spectrum (MS3) of the dissociated charged fragments can be produced. The primary ions emitted by the ion source (1) are first stored in the ion trap (2) (3), then the primary ions corresponding to a single primary mass peak are selected, eliminating the other ions. primary in the manner known to those skilled in the art of primary selection of the ion trap (2) (3) used. The primary ions selected by CID (acronym for "Collision Induced Dissociation") are dissociated at low kinetic energy and the dissociated neutral fragments are ionised and then again dissociated in a second step without primary mass selection. Charged dissociated in the first step, by CID (acronym for "Collision Induced Dissociation") at low kinetic energy and ionizes dissociated neutral fragments. The dissociation spectrum of the dissociated charged fragments in the second step is finally produced without primary mass selection. The pairs, and trios, are then identified with dissociation mass peaks corresponding to each dissociation spectrum (MS3) of each dissociation mass peak of the selected primary mass peak.

  Finally, each dissociation mass spectrum (MS3) is produced with pairs, and trios, of identified dissociation peaks. The foregoing steps can be repeated to produce the dissociation mass (MS) spectra without primary mass selection of any selected dissociation mass peak (MSn-2).

  Fourth embodiment of a spectrometer

  The fourth embodiment of a tandem mass spectrometer according to the invention is illustrated in FIG. 2. It comprises successively, according to the general direction of movement of the primary ions, a source of ions (1) multi-charged with electrospray ESI acronym Electron Spray Ionization, a Fourier Transform Ion Cyclotron Resonance Fourier Transform mass spectrometer (3), and a detector (4) measuring the cyclotron frequency of ions. In this embodiment, the Fourier transform mass spectrometer is used both as a dissociation device (2) and as a mass spectrometer (3). This tandem mass spectrometer embodiment is known to those skilled in the art who utilize identical mass spectrometers to produce primary mass selection dissociation mass spectra. The primary mass spectrum is first produced with the Fourier transform mass spectrometer after storage of the primary ions emitted by the ion source (1), without dissociation. Then, in a second acquisition, one dissociates without selection of primary mass for example by CID (acronym for "Collision Induced Dissociation") at low kinetic energy with the molecules of a neutral gas in the volume of the mass spectrometer. Fourier (2) (3), in pairs, and in trios, of charged fragments the stored primary ions. The Fourier transform dissociation mass spectrum is then produced without primary mass selection. The pairs and trios are then identified with dissociation mass peaks of each of the dissociation spectra corresponding to each primary mass peak with the method according to the invention. Each dissociation spectrum is finally produced with the pairs, and the trios, of identified dissociation mass peaks.

  In a variant of the fourth embodiment which has just been presented, the ion source (1) may be preceded by a device for separating the molecules by LC liquid chromatography acronym for Liquid Chromatography.

  In another variant of the fourth embodiment which has just been presented, the Fourier transform mass spectrometer (2) (3) is equipped with a device for ionizing the neutral fragments produced by the dissociation of the ions. in the device. This device can be an electronic impact ionization system or a pulsed or continuous laser ionization system. This device will allow the method according to the invention to be used in the MSn mode. After realizing the dissociation spectrum (MS-MS = MSZ) without primary mass selection with the dissociation of the primary ions by CID (acronym for "Collision Induced Dissociation") at low kinetic energy and the ionization of the dissociated neutral fragments, a second dissociation spectrum (MS3) of the dissociated charged fragments can be produced. The primary ions emitted by the ion source (1) are first stored in the Fourier Transform mass spectrometer (3), then the primary ions corresponding to a single primary mass peak are selected, eliminating the other primary ions according to the method known to those skilled in the art of primary mass selection of the Fourier transform mass spectrometer (2) (3) used. The primary ions selected by CID (acronym for "Collision Induced Dissociation") are dissociated at low kinetic energy and the dissociated neutral fragments are ionized, and the fragments are dissociated again in a second step without primary mass selection. Charged dissociated in the first step, by CID (acronym for "Collision Induced Dissociation") at low kinetic energy and ionizes dissociated neutral fragments. The dissociation spectrum of the dissociated charged fragments at the second stage is finally produced without selection of primary mass. The pairs and trios are then identified with dissociation mass peaks corresponding to each dissociation spectrum (MS3) of each dissociation mass peak of the selected primary mass peak. Finally, each dissociation mass spectrum (MS3) is produced with pairs, and trios, of identified dissociation peaks. The foregoing steps can be repeated to produce the dissociation mass spectra (MS ') without primary mass selection of any selected dissociation mass peak (MS' 2).

  In another variant of the fourth embodiment which has just been shown, illustrated in FIG. 8, the apparatus is equipped with a Q quadrupole mass spectrometer (5) positioned after the ion source (1) and a dissociation device q (2) consisting of a gas-containing multipolar waveguide for effecting the dissociation of the primary ions by CID at low kinetic energy, before introduction into the FTICR (3) of the ions. The quadrupole Q will make it possible to simultaneously select, with a large mass window, several primary mass peaks of interest, and to reduce the number of false pairs, and false trios, of dissociation mass peaks identified by the method according to the invention. 'invention.

  In another variant of the fourth embodiment which has just been presented, illustrated in FIG. 8, the apparatus is equipped with an ion trap (5) positioned after the ion source (1) and a dissociation device q (2) consisting of a multipole waveguide containing gas for effecting the dissociation of the primary ions by low kinetic energy CID before the introduction into the FTICR (3) of the non-dissociated primary ions and dissociated charged fragments. The ion trap (5) will make it possible to simultaneously select all the primary mass peaks of interest, and to reduce the number of false pairs, and false trios, of dissociation mass peaks identified by the method according to the invention. .

  In another variant of the fourth embodiment which has just been presented, also illustrated in FIG. 8, the dissociation device q (2) of the two preceding variants may be equipped with an ionization system for the dissociated neutral fragments. .

  By combining two of the preceding variants of the fourth embodiment which has just been presented, also illustrated in FIG. 8, by equipping the apparatus with an ion trap (5), and equipping the dissociation device q (2). with an ionization system dissociated neutral fragments, can be used the method according to the invention mode (MSn) as described above.

  The present invention is not limited to the embodiments described above and shown in the drawings, but the skilled person will be able to make many variations or modifications. In particular, it will also be able to modify the order of the steps according to the possibilities of the equipment involved, and to use the variants of each of the embodiments one by one, or combined, with each other.

  BIBLIOGRAPHIC REFERENCES [1] J.D. Pinston et al, Rev. Sci.Instrum., 57 (4), (1983), p.583. C. G. Enke et al, US Patent 4,472,631 (1984). [2] S. Della-Negra and Y. Leybec, Anal. Chem., 57 (11), (1985), p. 2035. K. G. Standing et al., Anal. Instrumen., 16, (1987), p; 173. R.J. Conzemius US Patent 4,894,536 (1990).

  [3] Alderdice et al, US Patent 5,206,508 (1993).

  [4] R. H. Bateman, J.M. Brown, D.J. Kenny, US Patent 2005/0098721 A1 (2005).

  [5] C. G. Enke, patent PCT / US2004 / 008424.

  [6] R.D. Smith et al, US Patent 5,073,713 (1991). 20

Claims (10)

  A method of tandem mass spectrometry, characterized in that it comprises the following steps: (a) providing a source of primary ions to be analyzed, (b) generating a primary mass spectrum of the primary ions without dissociation, this spectrum containing peaks of occurrences of primary ions; (c) from this spectrum, determine for each of the primary mass peaks it contains the value of the mass-to-charge ratio function of the primary ions of the mass spectrometer used corresponding to the maximum number of occurrences of this peak, and the electric charge Q of the primary ions, (d) from these data, determine correlation laws in the form of linear equations of each of the primary mass peaks, giving all possible pairs, and all trios, of values the function of the mass-to-charge ratio of the dissociated charged fragments of the mass spectrometer used corresponding to maxima of occurrences of pairs, and trios, possible of dissociation mass peaks produced by pairs, and trios, possible fragments charged likely to come from the dissociation of identical primary ions having the same mass-to-charge ratio (M / Q), (e) dissociating primary ions without primary mass selection, at low kinetic energy, so as to obtain for each of them a pair, or a trio, of charged fragments, (f) to generate a dissociation spectrum, without primary mass selection, containing the dissociation mass peaks of each of the spectra of dissociation corresponding to each primary mass peak, (g) from this spectrum, determine for each of the dissociation mass peaks that it contains each value of the function of the mass-to-charge ratio of the dissociated charged fragments of the mass spectrometer used corresponding to the maximum number of occurrences of this peak, (h) generating from the measured values of the mass-to-charge ratio function of the dissociated charged fragments of the mass spectrometer used corresponding to the maxima of occurrences of the dissociation peaks all the pairs , and all the trios, potentials of these values, (i) identify, among the said potential pairs and trios, the actual pairs and trios that satisfy a criterion of proximity to the correlation laws, and thereby identifying the pairs, and trios, of dissociation mass peaks corresponding to the same peak of the primary mass spectrum, (j) producing each dissociation spectrum corresponding to each of the mass peaks primary, with pairs, and trios, of dissociation mass peaks corresponding to pairs, and trios, real identified. to   2. Method according to claim 1, characterized in that the pairs of dissociated charged fragments are derived from the dissociation at low kinetic energy of multicharged primary ions in pairs of charged fragments, and the dissociation at low kinetic energy of ions. multicharged primers in trios of fragments each containing a pair of charged fragments and a neutral fragment of known mass.   3. Method according to claim 1, characterized in that the dissociated charged fragment pairs are derived from the low kinetic energy dissociation of multicharged and / or mono-charged primary ions dissociating into pairs of neutral and charged fragments, with ionization of dissociated neutral fragments.   4. Method according to one of claims 1, characterized in that the trios of dissociated charged fragments are derived from the dissociation at low kinetic energy of multicharged primary ions dissociating into trios of charged fragments, and the dissociation to low kinetic energy of multicharged primary ions in trios of fragments each consisting of either a pair of charged fragments and a neutral fragment, or a pair of neutral fragments and a charged fragment, with ionization of the neutral fragments dissociated. 30   5. A tandem mass spectrometer comprising, according to the general direction of movement of the ions: an ion source (1); means for supplying a primary mass spectrum of these primary ions derived from these ionized molecules; so as to be able to identify the value Finax (M / Q) of the mass-to-charge ratio function of the primary ions of the mass spectrometer used corresponding to the maximum number of occurrences and the primary electric charge Q, corresponding to each primary mass peak of these ions, - a device for dissociating (2) the primary ions so as to obtain, for each of them, a pair, or a trio, of charged fragments, - a mass spectrometer (3), producing the mass spectrum primary ion, and the dissociation spectrum without primary mass selection of the charged fragments, - an ion detector (4), -means of identification, in the set of dissociation mass peaks, of the pairs and trios, mass peaks e of dissociation corresponding to pairs and trios of charged fragments resulting from the dissociation of primary ion parents with the same mass-to-charge ratio, these identification means being arranged so that the identification is based on the measured values Finax (m / q) the function of the mass-to-charge ratio of the dissociated charged fragments of the mass spectrometer used corresponding to the maxima of occurrences of the dissociation mass peaks, and of predetermined correlation laws, giving the possible pairs and trios of these values. 25   6. Tandem mass spectrometer comprising according to the direction of general movement of the ions: - an ion source (1), - means for supplying a primary mass spectrum of these primary ions from these ionized molecules, so as to be able to identify the value Fmax (M / Q) of the function of the mass-to-charge ratio of the primary ions of the mass spectrometer corresponding to the maximum of occurrences and the primary electric charge Q, corresponding to each primary mass peak of these ions, - a device (5) for simultaneously selecting and injecting into the dissociation device (2), the primary ions from the primary mass peaks of the molecules of interest, - a device for dissociating the primary ions in pairs, and in trios, charged fragments (2), - a mass spectrometer (3), producing the primary mass spectrum of the primary ions, and the dissociation spectrum without primary mass selection of charged fragments s, -a ion detector (4). means for identifying, in the set of dissociation mass peaks, pairs and trios of dissociation mass peaks corresponding to pairs and trios of charged fragments resulting from the dissociation of primary ion parents, and Mass to charge ratio, said identification means being arranged so that the identification is based on the measured values Fmax (m / q) of the mass-to-charge ratio function of the dissociated charged fragments of the mass spectrometer used corresponding to the maxima occurrences of dissociation mass peaks, and predetermined correlation laws, giving the possible pairs and trios of these values.   Tandem mass spectrometer according to claims 5 and 6, characterized in that: the source of primary ions (1) is a source of multicharged and / or mono charged ions; dissociation (2) of primary ions in pairs, and trios, of fragments is equipped with a system ionizing the neutral fragments from the dissociation at low kinetic energy of the primary ions. 30   8. Tandem mass spectrometer, according to claim 6 and 7, characterized in that: - the device (5) for simultaneously selecting the primary ions primary mass peaks of interest is an ion trap, - the ion trap (5) also makes it possible to use the method according to the invention in the (MSn) mode for both the multicharged and / or mono-charged primary ions, if the device (2) is equipped with a system ionization of the dissociated neutral fragments, by performing the following steps: * primary ions, or dissociated charged fragments, of the same mass-to-charge ratio are selected with the mass selection mode of the ion trap (5), 10 * in the ion trap (5), the primary ions or the dissociated charged fragments selected in a first dissociation step are dissociated into dissociated charged fragments by collision with the molecules of a gas and then injected. , in a second st The dissociated charged fragments produced in the dissociation device (2) where they are fragmented again, and the dissociated neutral fragments are ionized with the ionization system of the neutral fragments of the dissociation device, are dissociated without primary mass selection. dissociation (2), to produce the pairs and trios of charged fragments, said pairs and trios of dissociated fragments are introduced into the mass spectrometer (3) to produce the dissociation spectrum without primary mass selection of the dissociated charged fragments in the first dissociation step.   9. Tandem mass spectrometer according to claims 5, 6, 7, and 8, characterized in that: - the device for dissociation (2) of the primary ions in pairs, and in trios, of charged fragments low kinetic energy is a multipolar waveguide containing gas dissociating primary ions by multiple collisions with gas molecules, - the multipolar waveguide is equipped with a system ionizing neutral fragments from low energy dissociation kinetics of the primary ions in the multipolar waveguide (2).   10. A computer program adapted to be implemented in a tandem flight time mass spectrometry system and comprising a set of instructions able to perform the following steps: (a) control the system so that it generates from a source of primary ions to be analyzed, a primary mass spectrum of these primary ions, without dissociation, this spectrum containing peaks of occurrences of primary ions, (b) perform an acquisition of the data of this spectrum, (c) from said data, determine for each of the primary mass peaks it contains the value Finax (MJQ) of the mass-to-charge ratio function of the primary ions of the mass spectrometer used corresponding to the maximum of occurrences of this peak, and the electric charge Q of the primary ions, (d) from these peak data, determine correlation laws giving all possible pairs and trios of values of the function of the mass-to-charge ratio of the frag dissociated charged elements of the mass spectrometer used, corresponding to maxima of occurrences of pairs and possible trios of dissociation mass peaks produced by pairs, and trios, of charged fragments from the different primary ions, (e) controlling the system to cause dissociation of the primary ions so as to obtain for each of them, a pair, or trio, charged fragments, (f) generating, without primary mass selection, a dissociation spectrum of these dissociated charged fragments containing the dissociation mass peaks of each of the dissociation spectra corresponding to each primary mass peak, (g) from this spectrum, determine for each of the dissociation mass peaks that it contains each value Finax (m / q) of the function of the mass-to-charge ratio of the dissociated charged fragments of the mass spectrometer used corresponding to the maximum number of occurrences of this peak, (h) to generate at taking values from all the pairs, and trios, potentials of these values, (i) identifying, from among said potential pairs and trios, the actual pairs and trios that satisfy a proximity criterion with respect to the correlation laws, and identifying Thus the pairs, and trios, of dissociation mass peaks corresponding to the same peak of the primary mass spectrum, (j) producing each dissociation spectrum corresponding to each of the primary mass peaks, with pairs and trios of peaks of dissociation mass corresponding to the actual identified pairs and trios.