DE10351010B4 - mass spectrometry - Google Patents

Abstract

Magnetic sector mass spectrometer with:
A magnetic sector mass analyzer;
A collector slot (3) located downstream of the magnetic sector mass analyzer;
- A device (13) which is arranged downstream of the collector slot (3) to disassemble a collector of the slot (3) transmitted ion beam in at least a first and a second ion beam;
- at least one first detector (14a, 14c) for measuring the intensity of at least part of the first ion beam;
- at least one second detector (14b, 14d) for measuring the intensity of at least part of the second ion beam;
the collector slot (3) being arranged so that analyte ions of interest in the ion beam are evenly distributed over the collector slot (3) and / or distributed symmetrically about the center of the collector slot (3);
wherein the device (13) is arranged so that substantially half of the analyte ions in the ion beam fall on the at least one first detector (14a, 14c) and the other half of the analyte ions in the ion beam on the ion beam.

Description

The The present invention relates to a magnetic sector mass spectrometer and a method for mass spectrometry.

Magnetic sector mass spectrometer are commonly used for target component trace analysis, for accurate Mass measurements, for Isotope ratio measurements and for used basic ion chemistry studies. Magnetic Sector Mass Spectrometer are for it set up ions with a certain mass-to-charge ratio too to pass an ion detector. As further details below is described, ions travel in a substantially circular trajectory through the magnetic sector mass analyzer. A magnetic sector mass analyzer can be described in more detail as an ion impulse analyzer if however, the initial energies of the ions are substantially the same, the ions are separated according to their mass-to-charge ratio.

und daher: v2 = 2zeVm When ions with a mass m and a charge ze are accelerated by an electric potential difference V, they reach a velocity v and have a kinetic energy ε, where:

and therefore: v 2 = 2zeV m

Ions with a charge ze moving through a magnetic field B at a velocity v undergo a Lorentz force F in a direction orthogonal to the direction of the magnetic field and also to the direction of movement of the ions. The Lorentz force F exerts a centripetal force on the ions, causing them are caused to run on a circular trajectory with a radius r _m . The Lorentz force F is:

und es gilt daher:

Accordingly, the mass-to-charge ratio of the ions passing through the magnetic field is given by:

and it therefore applies:

Therefore, by eliminating v ² from the above equation for mass-to-charge ratio:

It Thus, it can be seen that the values of the magnetic field B and the potential difference V can be set so that ions with a certain mass-to-charge ratio, the from an ion source, from the magnetic sector to the Ion detector are allowed to pass. In this way the magnetic sector works as a mass-to-charge ratio filter. Accordingly, a mass spectrum can be obtained by scanning either the Magnetic field B and / or the potential difference V are recorded.

For some Applications can Several ion detectors are provided so that ions with different mass-to-charge ratios simultaneously can be recorded wherein each ion assumes a different trajectory through the magnetic sector. Alternatively, a field of detectors can be used to simultaneously to record part of the mass spectrum.

According to another arrangement, the magnetic field can be kept substantially constant, so that ions are dispersed according to their momentum. The momentum ρ of an ion with a mass m, a velocity v and a kinetic energy ε is given by: ρ = mv = √ 2mε

Therefore become ions with a constant kinetic energy ε effectively dispersed according to their mass.

The Shape of a magnetic sector can be designed to have ion-direction focusing characteristics having. A magnetic sector mass analyzer can be designed to that he has a certain combination of mass dispersion and directional focusing properties in the direction of mass dispersion.

A conventional single-focus magnetic sector mass spectrometer has an ion source, a magnetic sector mass analyzer, and a collector slot. The ion source has a limited emission range or width, which defines the width of the ion beam emitted by the ion source. The magnetic sector mass analyzer may have convergent directional focusing characteristics to provide the Focus ions on a pixel in a focal plane downstream of the magnetic sector mass analyzer. In a single focusing magnetic sector mass spectrometer, an ion collector slot is located at the pixel of the ion source slot. The direction focusing properties of the magnetic sector mass analyzer can be set to a very high degree. However, the imaging characteristics of the magnetic sector mass analyzer are limited by the width of the initial energy of the ions.

The mass dispersion coefficient D _{m of} a single-focusing magnetic sector mass spectrometer is proportional to the radius of curvature r _{m of} the ion trajectory in the magnetic field. The spatial separation y of two ions with different masses of a mean mass m and a mass difference Δm refers to the mass dispersion coefficient D _m and is:

The ion beam width w _b at the image position downstream of the magnetic sector mass analyzer is related to the slit width w _{s of} the ion source, the lateral magnification M of the image and the sum of the image aberration coefficients Σα as follows. w b = Mw s + Σα

The mass resolving power m / Δm for a collector slit having a collector slit width w _c is given by:

Accordingly, the mass dispersion coefficient D _m , the ion source slit width w _s and the collector slit width w _{c are} the most important parameters in determining the mass resolution of a magnetic sector mass spectrometer. However, the final mass resolution is limited by the sum of the image aberrations.

As discussed above, magnetic sectors that use a constant magnetic field disperse ions with respect to the ion pulse, and therefore with respect to the ion mass, if the ions are monoenergetic. However, ions are usually not monoenergetic and often have a range of kinetic energies, depending on the particular type of ion source used to generate the ions. The width of the ion energies causes the ion beam width w _b to widen at the image position, and this typically becomes the limiting factor in achieving high resolution.

The pulse dispersion may be considered as having a combination of a bulk dispersion and an energy dispersion. There are known electrical sectors which disperse ions according to their energy. Accordingly, if an electric sector is combined with a magnetic sector, the total energy dispersion of the ions can be modified. Dual-focus magnetic sector mass analyzers are known which comprise a combination of a magnetic sector mass analyzer and one or more electrical sectors providing directional focusing and wherein the total energy dispersion is zero. If the double focusing magnetic sector mass analyzer has an electric sector with an energy dispersion D _e1 and a magnetic sector with an energy dispersion D _e2 , where the image magnification is M ₂ , the total energy dispersion D _{e of} the double focusing magnetic sector mass spectrometer is: D e = M 2 D e1 + D e2

The electrical sector may precede or follow the magnetic sector, or alternatively two smaller electrical sectors may be provided, one provided upstream of the magnetic sector and the other downstream of the magnetic sector. As long as the total energy dispersion D _{e is} zero, the arrangement can be considered as a double focusing magnetic sector mass analyzer. A combination of magnetic and electrical sectors may be established which do not have the image spreading problems associated with a single-focus magnetic sector mass spectrometer. Accordingly, double focus magnetic sector mass spectrometers are capable of achieving much higher resolutions than simple focusing magnetic sector mass spectrometers.

The Combination of a magnetic sector and one or more electrical sectors for providing a double focusing magnetic sector mass spectrometer allows in the design choice enough degrees of freedom to achieve a focus relatively high To allow order. Double focusing magnetic sector mass spectrometers, where all directional and energy focusing terms are close to or substantially zero, are known, and these mass spectrometers can correspond to resolving power of more than 150000 the valley definition of 10% (which will be described in more detail below will reach.

The mass resolution for a peak width in mass units of Δm at the mass m is m / Dm. If the peak _width w _pk at the base is measured, the mass resolution m / Δm for an ion beam width w _b and a collector slot width w _{c is} theoretically given by:

It however, it is not practical to measure the peak width at the base, and the peak width is therefore conventionally measured at 5% of the peak height. The at 5% of the height measured peak width is used to increase the resolution to calculate. This is known as the 10% thumb definition of the resolution, because, if two peaks of different mass, but the same intensity or height, overlap each other at one point or cut that 5% of their height is, the resulting tip profile has two peaks with an intermediate one Valley, which is 10% of the height the peaks is. If a magnetic sector mass spectrometer for example, a mass resolution of 1000 according to the valley definition of 10% would have two same intensity peaks with the masses 1000 and 1001 being resolved so that the valley between the peaks of the resulting peak profile 10% of the height of the two Peaks would amount.

As discussed above, the spatial separation y of two ions of different masses at a mean mass m and a mass difference Δm is related to the dispersion coefficient D _m . This relationship can be used to the real width of an ion beam _b w on collector slit in terms of the fractional mass difference of the ions Dm / m expressed as follows:

The term for the fractional mass difference of ions Δm / m is dimensionless and is typically expressed in parts per million (ppm) where:

Accordingly, the beam width w _b can be expressed in ppm of mass when the dispersion coefficient D _{m of} the mass spectrometer is known. The collector slot width _wc can also be expressed in ppm by mass as follows:

When an ion beam of width w _{b is} deflected across a collector slit of width w _c and the transmitted ions are detected and recorded, the recorded peak _profile has a width w _pk where: w pk = w b + w c

The peak _width w _pk can also be expressed as ppm of mass:

Of the Inverse of the mass resolution m / Δm of the Mass analyzer gives the mass resolution Δm / m. Therefore, the mass resolution as expressed in ppm of the mass Peak width can be viewed.

The capacity double focusing magnetic sector mass spectrometer for a high resolution leads to their use for exact mass measurements and for a highly specific target link trace analysis by a high-resolution selective ion recording (High Resolution Selective Ion Recording - HR-SIR) known technique. In conventional high-resolution selective ion recording techniques becomes a double-focusing Magnetic sector mass spectrometer used to address the response of Target connections at a high resolution and with a high sensitivity select and record. The high resolution allows that chemical background masses are effectively eliminated, and they allows thus achieving a lower detection level. The high-resolution selective ion recording therefore offers a higher duty cycle than other conventional Techniques and with that this an improved sensitivity.

The EP 0 551 999 A1 discloses a magnetic sector mass spectrometer with a Time of Flight mass analyzer. The Time of Flight mass analyzer has an ionic mirror with specific properties. The purpose of the Time of Flight mass analyzer is to determine the mass-to-charge ratio of the ions based on their time of flight.

di US 4 524 275 A describes a magnetic sector mass spectrometer in which the magnetic sector has curved pole faces. Due to the special geometric design, the traversing ions are separated according to their mass / charge ratio and leave the magnetic sector on different tracks. The separated ion beams are fed to different detectors to determine the ratio of the isotopes in the original ion beam.

The detection and quantification of polychlorinated dibenzo-p-dioxins and in particular of 2,3,7,8-tetrachlorinated dibenzo-p-dioxin ("2,3,7,8-TCDD") is a particularly important application of double-focusing magnetic sector mass spectrometers. Despite costly purification procedures, samples still contain compounds such as polychlorinated biphenyls and benzyl phenyl ethers which have the same nominal masses as the compounds of interest. Samples are conventionally spiked with a known amount of a ¹³ C isotope-labeled form of 2,3,7,8-tetrachlorinated dibenzo-p-dioxin which has been gas chromatographed and recorded by high resolution mass spectrometry. The measurement is quantified by comparing the response of native dioxin with that of the ¹³ C labeled form and checked by confirming the ratio between the major isotopes of both native and ¹³ C-labeled dioxin. At a resolution of 10,000 (10% valley definition), the conventional detection level for 2,3,7,8-tetrachlorinated dibenzo-p-dioxin in the absence of other interfering components is about 1 femtogram or 3 attomoles.

One Magnetic sector mass spectrometer with a single ion detector can be used to record a mass spectrum by scanning and subsequent Detecting different mass peaks are used. The duty cycle for recording mass in the mass spectrum is generally relatively small, and the higher the resolution or the wider the mass range becomes, the lower the duty cycle becomes. Different As a quadrupole mass filter, a magnetic sector mass analyzer designed for it be the signal from ions with several different masses at the same time record. This is commonly referred to as a parallel detection.

Several Detectors provide a means for accurately recording the relative frequency of two or more different masses at the same time. The simultaneous accurate recording of the relative frequencies of, for example two isotopes is particularly accurate because this technique is essentially not by fluctuations or drift of the ionization source or by changing fast Sample concentrations, often For example, in the chromatography, is affected. Magnetic sector mass spectrometer, which have a plurality of collector slots, and corresponding separate discrete ones Ion detectors can therefore, be used to make accurate isotope ratio determinations. Different ion detectors are needed to get different ones Record masses, but only at a low resolution of for example 200-300 (10% valley definition).

According to one other conventional Arrangement allows a field detector a simultaneous detection over a mass range, whereby the duty cycle improves when recording a mass spectrum is used. Field detectors where high density fields are more discrete Charge-sensitive detectors or single sensitive for the ion position Detectors are very sensitive, but they are usually limited in size. Such field detectors are arranged along the focal plane of the mass spectrometer and therefore replace the collector slot, which would otherwise normally in connection with an ion detector in a magnetic sector mass spectrometer is used. Each separate detector in the field therefore replaces determine the collector slot, and these separate detectors the resolution of the mass spectrometer. Because the detector has several masses at the same time must record he can in practice only up to a medium resolution, for example up to a resolution of about 2000 (10% valley definition). This resolution is for the Analysis of polychlorinated dibenzo-p-dioxins is still too low.

Conventional high resolution selective ion recording techniques for the detection of traces of 2,3,7,8-tetrachlorinated dibenzo-p-dioxin exhibit repeated rapid switching to at least four different masses at high resolution and recording the signal response for all four masses. This is commonly done at a mass resolution of about 10,000 (10% valley definition) to ensure that other isobaric components that elute from the gas chromatographic column are separated out. In practice, an additional reference material is usually introduced continuously into the ion source of the mass spectrometer so that an additional reference mass peak, which is in the vicinity of the mass of the track compound to be analyzed, is continuously present. The additional reference ground is included in the switching sequence so that any drift on the mass scale can be monitored and corrected. The mass scale drift can be monitored by scanning over the reference peak to determine any shift in the peak center. If drift on the mass scale is not monitored, switching to the top of each of the four masses of interest could not be done with the degree of accuracy required. It is also known to switch to the reference peak at a second time in each sequence to confirm that the switching operation is correct and accurate. This procedure ensures accurate switching at a resolution of 10000 (10% valley definition). However, while this procedure is sensitive, it does not ensure that all detected ions are actually only ions of the target compound of interest. Accordingly Kings NEN interference ions are also detected unintentionally.

interference ions can for example due to contaminant materials in the ion source, Reference material, leaking material from the gas chromatography column or other co-eluting components from the gas chromatograph, the very similar Mass-to-charge ratios as the intended analyte ions have detected. These Interference ions can be detected because they themselves at a resolution of 10000 (10% valley definition) not completely separated from the analyte ions can be. Interference ions can also by scattering due to ions from other components that with higher frequency are present and collide with residual gas molecules.

Of the Main note on the presence of significant interference consists in a distortion of the isotope ratio. Such a distortion is usually checked as part of a standard test procedure. Even however, if it is known that interference ions are present by it is recognized that the particular isotope ratio is distorted, the presence carries the interference ions continue to provide a background signal indicating the detection can cover the trace analyte ions of interest. Switching From tip to tip, there is no way to check whether the detected ions actually the ions of interest are, and it does not help make a determination that the measured ion signal due to a significant presence of interference ions rejected should be.

It is therefore desirable an improved magnetic sector mass spectrometer provide.

According to the present Invention is a magnetic sector mass spectrometer provided with the features of claim 1.

Of the Ion beam has a first and a second direction that are orthogonal to each other. According to the preferred embodiment The ions in the ion beam are converted according to their mass-to-charge ratio the first direction dispersed so that the mass-to-charge ratio of Changes ions in the ion beam along the first direction. Preferably the ions in the ion beam do not substantially become corresponding their mass-to-charge ratio in dispersed in the second direction, so that the mass-to-charge ratio of the Ions in the ion beam along the second direction substantially is constant.

According to the preferred Measure embodiment the first and the second detector detect the intensities of at least one part of the first and second ion beams at substantially the same time.

The Mass spectrometer may be a single-focusing magnetic sector mass spectrometer or a double focusing magnetic sector mass spectrometer.

According to the preferred Embodiment has the device for dividing the permeated by the collector slot Ion beam on an electrode. The electrode will be on one Potential kept that ions on the first and the second detector reflected or distracted. The electrode preferably closes a sheet with a fine edge or a wedge-shaped electrode, and it can when using for it be ensured that analyte ions in the ion beam, the Approach edge, substantially uniform and / or be arranged symmetrically with respect to the edge. interference ions in the ion beam, which approach the edge of the electrode, can in essentially uneven and / or be arranged asymmetrically with respect to the edge.

The Magnetic sector mass spectrometer preferably has an electron impact ion source ("EI ion source") or an ion source with chemical ionization ("CI ion source") on. Alternatively, the ion source may be an electrospray ion source ("ESI ion source") Atmospheric pressure ion source with chemical Ionization ("APCI ion source"), a Atmospheric pressure photoionization ion source ("APPI ion source"), a Matrix Assisted Laser desorption ionization ion source ("MALDI ion source"), a Laser desorption ionization ion source ("LDI ion source"), a inductively coupled plasma ion source ("ICP ion source"), a Fast atom bombardment ion source ("FAB ion source"), a liquid secondary ion mass spectrometry ion source ("LSIMS ion source"), a Field ionization ion source ("FI ion source") and a Field desorption ion source ("FD ion source"). The Ion source can be a continuous or a pulsed ion source be.

Preferably is between the device for splitting the ion beam and the Ion source maintain a voltage difference. The voltage difference can 0-100 V, 100-200 V, 200-300 V, 300-400 V, 400-500 V, 500-600 V, 600-700 V, 700-800 V, 800-900 V, 900-1000 V or more than 1000 V.

The preferred magnetic sector mass spectrometer may further include a processor for determining the intensity of at least a portion of the first ion beam with respect to the intensity at least a portion of the second ion beam. If the intensity of at least a part of the first and / or the second ion beam deviates from the intensity of at least a part of the second and / or the first ion beam by at least x percent, it can be determined that the ion beam has a considerable amount of interference ions. Preferably, the percentage x is selected from among 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100 or more than 100 existing group selected. Alternatively or additionally, if within a time t the number of ions detected by the first detector deviates from the number of ions detected by the second detector by at least y standard deviations of the total number of ions detected by the first and second detectors during the time t in that the ion beam has a considerable amount of interference ions. Preferably, the number of standard deviations y is selected from the group consisting of 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0, 2.25, 2.5, 2.75, 3.0, 3.25, 3.5, 3.75, 4.0 or more than 4.0.

According to a preferred embodiment, the signals from the first and second detectors are summed to produce a combined signal, and the combined signal can be multiplied by a weighting factor. Preferably, the weighting factor does not significantly attenuate the combined signal when the signal from the first detector is substantially equal to the signal from the second detector. Additionally or alternatively, the weighting factor can significantly attenuate the combined signal if the signal from the first detector differs significantly from the signal from the second detector. According to one embodiment, the weighting factor is of the form exp (-ky ⁿ ), where k and n are constants and within a time t the number of ions detected by the first detector is y standard deviations of the total number of the first and second detectors during the time period Time t detected ions differs from the number of ions detected by the second detector. According to this embodiment, the difference between the number of ions detected by the first and second detectors is assumed to be a positive value, ie, the modulus of the difference between the number of detected ions. Preferably, the constant k is 0.5-2.0, 0.6-1.8, 0.7-1.6, 0.8-1.4, 0.9-1.2, 0.95-1 , 1 or 1. Preferably, the constant n is 1.0-3.0, 1.2-2.8, 1.4-2.6, 1.6-2.4, 1.8-2.2, 1.9-2.1 or 2.

According to the preferred Embodiment, if it is determined that the ion beam has a significant Share of interference ions, signals from the first and / or rejected by the second detector or otherwise than relatively inaccurate considered. Alternatively, if it is determined that the ion beam does not show a significant proportion of interference ions Signals from the first and second detectors are summed or added to others Way as relatively accurate considered.

Preferably The magnetic sector mass spectrometer further has a downstream of Collector slot arranged lens. The lens can be the picture of the collector slot on the device for disassembling the ion beam refocus or substantially collimate the ion beam.

According to one another embodiment is a shield tube for guiding of ions to the device to split the ion beam. The shielding tube is preferably between the collector slot and the apparatus for disassembling the ion beam are arranged and can the ion beam of the at the first and / or the second Shield detector applied voltages. Preferably, the first and / or the second detector one, two, three, four, five, six, seven, eight, nine, ten or more than ten microchannel plate detectors on. additionally or alternatively the first and / or the second detector one, two, three, four, five, six, seven, eight, nine, ten or more than ten conversion dynodes to generate of electrons in response to ions on the conversion dynode (s) fall. The mass spectrometer may additionally include one or a plurality of electron multipliers and / or one or more microchannel plate detectors for receiving electrons generated from the conversion dynodes. According to one another embodiment the mass spectrometer further comprises one or more scintillators and / or one or more phosphors, of which those of the Conversion dynode or the conversion dynodes generated electrons so that the one or more scintillators and / or the one or more phosphors in response to receiving of electrons generate photons. The mass spectrometer can also one or more photomultiplier tubes and / or one or more Photosensitive solid-state detectors for detecting the photons.

In accordance with the preferred embodiment, the magnetic sector mass spectrometer further includes an additional detector disposed upstream of the first and second detectors. This additional detector may have a conversion dynode, and in one mode of operation, at least a portion of an ion beam is deflected to the conversion dynode of the additional detector so that the conversion dynode generates electrons in response thereto. The additional detector may further include one or more electron multipliers and / or one or more microchannel plate detectors for receiving the electrons generated by the conversion dynode. One or more scintillators and / or one or more phosphors may also be provided to receive electrons generated by the conversion dynode and generate photons in response thereto. These photons can be detected by one or more photomultiplier tubes and / or one or more photosensitive solid state detectors.

Preferably can the reinforcement the first and / or the second detector are set independently, and according to a Embodiment will be the first and second detectors by independently adjustable power supplies fed. The first and second detectors may further include one or more Analog-to-digital converter and / or have one or more Ionenzähldetektoren.

According to one another preferred embodiment the magnetic sector mass spectrometer continues to provide adjustment means for centering the ion beam on the device for disassembly of the ion beam. The adjusting means preferably have at least one downstream arranged on the collector slot deflecting electrode, which is set up for is the ion beam with respect to the device for disassembling the To move ion beam.

The Magnetic sector mass spectrometer according to the preferred embodiment is particularly suitable for target compound trace analysis.

According to one In another aspect, the present invention provides a method for Mass spectrometry with the features of claim 30 before.

Of the Ion beam has a first direction and a second orthogonal Direction up. According to the preferred Processes are the ions in the ion beam according to their Mass-to-charge ratio dispersed in the first direction, so that the mass-to-charge ratio of Changes ions in the ion beam along the first direction. Preferably the ions in the ion beam do not substantially become corresponding their mass-to-charge ratio in dispersed in the second direction, so that the mass-to-charge ratio of Ions in the ion beam along the second direction substantially is constant.

According to the preferred Measure embodiment the first and the second detector detect the intensities of at least one part the first and second ion beams substantially simultaneously. at the method is further the intensity of at least a portion of first ion beam with respect to the intensity of at least a part of the second ion beam determined. If the intensity is at least a portion of the first and / or second ion beam from the intensity at least a portion of the second and / or the first ion beam can differ by at least a percentage x, it can be stated that the ion beam contains a significant amount of interference ions having. The percentage x can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100 or greater than 50 be. Alternatively or in addition if, within a time t, the number of times from the first detector detected ions from the number of detected by the second detector Ions by at least y standard deviations of the total number of first and detected by the second detector during the time t Ion deviates, it can be determined that the ion beam one significant proportion of interference ions. Preferably the number of standard deviations y 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0, 2.25, 2.5, 2.75, 3.0, 3.25, 3.5, 3.75, 4.0 or greater than 4.0.

In a preferred embodiment, the method further sums signals from the first and second detectors to produce a combined signal, and multiplies the combined signal by a weighting factor. Preferably, the weighting factor does not significantly attenuate the combined signal when the signal from the first detector is substantially equal to the signal from the second detector. Additionally or alternatively, the weighting factor can significantly attenuate the combined signal if the signal from the first detector differs significantly from the signal from the second detector. In one embodiment, the weighting factor is of the form exp (-ky ⁿ ), where k and n are constants, and within a time t, the number of ions detected by the first detector from the number of ions detected by the second detector are y standard deviations from the total differs from the first and the second detector detected during the time t ions. According to this embodiment, the difference between the number of ions detected by the first and second detectors is assumed to be a positive value. Preferably, the constant k is 0.5-2.0, 0.6-1.8, 0.7-1.6, 0.8-1.4, 0.9-1.2, 0.95-1 , 1 or 1. Preferably, the constant n is 1.0-3.0, 1.2-2.8, 1.4-2.6, 1.6-2.4, 1.8-2.2, 1.9-2.1 or 2.

If it is determined in accordance with the preferred method that the ion beam has a significant amount of interference ions, the signals from the first and / or second detectors may be discarded or otherwise considered to be relatively inaccurate. Alternatively, if it is found that the ion beam does not have a significant amount of interference ions, For example, signals from the first and second detectors may be summed or otherwise considered to be relatively accurate.

Various embodiments of the present invention will now be described together with other arrangements, for explanatory purposes only serve as an example with reference to the attached drawings described, wherein:

1 shows a conventional simple focusing magnetic sector mass spectrometer,

2 shows a conventional double-focusing magnetic sector mass spectrometer,

three shows a conventional measurement of 2,3,7,8-tetra chlorinated dibenzo-p-dioxin obtained by high resolution selective ion recording,

4 shows an ion detector according to a preferred embodiment of the present invention,

5 Fig. 4 shows an embodiment in which a lens is used to focus an ion beam which has passed through a collector slit onto the input port of an ion detector according to the preferred embodiment;

6 a particularly preferred embodiment in which ions are detected using conversion dynodes in combination with microchannel plate detectors,

7 another embodiment in which two detectors are provided on each side of a reflective electrode,

8th 1 shows an embodiment in which ions can be conducted to a preferred ion detector in an operating mode and in which, in another operating mode, ions can be deflected to a second detector system,

9 shows a typical tip profile that can be observed using a conventional ion detector,

10 shows the peak profiles that can be observed using an ion detector according to the preferred embodiment,

11 shows the effect of a small positional shift of an ion beam having 20 ions falling on the collector slot of an ion detector according to the preferred embodiment with a high resolution of 10000, and

12 shows the effect of a small shift in the position of an ion beam having 100 ions falling on the collector slot of an ion detector according to the preferred embodiment with a low resolution of 2000.

A conventional simple focusing magnetic sector mass spectrometer is in 1 shown. The mass spectrometer has an ion source 1 , a magnetic sector mass analyzer 2 and a collector slot three located immediately upstream of an ion detector (not shown). The ion source 1 has a slot 4 on, the width of one of the ion source 1 determines the exiting ion beam. The in 1 illustrated magnetic sector mass analyzer 2 has convergent directional focusing properties. An ion collector slot three is at the pixel of the ion source slot 4 arranged so that a simple focusing magnetic sector mass spectrometer is provided. Although the directional focusing characteristics of the simple focusing magnetic sector mass spectrometer can be designed to reach a very high degree, its imaging properties are due to the energy width of the ion source 1 limited to emitted ions.

2 shows a conventional double focusing mass spectrometer. The mass spectrometer has an ion source 1 with a source slot 4 on. Ions from the ion source 1 run through a first electrical sector 5 and become a first intermediate image 6 brought. The ions then pass through the magnetic sector mass analyzer 2 and become a second intermediate image 7 brought before before focusing on a collector slot three through a second electrical sector 8th to run. The electrical sectors 5 . 8th serve to reduce the dispersion of the ions having different energies which would otherwise cause the image width to increase and which would therefore limit the resolution of the mass spectrometer.

three FIG. 12 shows a conventional measurement of signal intensity as a function of retention time in a gas chromatograph for a solution containing 5 fg 2,3,7,8-tetrachlorinated dibenzo-p-dioxin prepared using a conventional double focusing magnetic sector mass spectrometer with a resolution of 10000 (10% valley definition) adjusted to monitor ions with a molecular weight of 321.8936. It can be seen from this measurement that the detection level for 2,3,7,8-tetrachlorinated dibenzo-p-dioxin is limited by the noise generated by other ions passing through the collector slot, some of which are compounds, the same nominal mass as the analyte. It can be seen in this example that the detection level is limited to about 1 fg (3 attomoles).

A preferred embodiment of the present invention will now be described with reference to FIGS 4 and 5 described. A mass spectrometer according to the preferred embodiment comprises a split ion detector 11 with two or more separate detectors 14a . 14b related to a single collector slot three are provided (see 5 ). Ions coming from the single collector slot three be passed through, run into the split ion detector 11 and are passed through a reflective electrode 13 , depending on the position of the ions and the direction in which the ions move, in the direction of the mass dispersion on the one side or the other side of the reflective electrode 13 divided up. The of the reflective electrode 13 Reflected ions become one of two or more detectors 14a . 14b directed.

An ion beam that flows evenly across the collector slot three is distributed and / or symmetrical about the center of the collector slot three is substantially equally divided so that substantially half of the ions in the ion beam from the reflective electrode 13 is reflected, allowing it to one of the detectors 14a . 14b while the other half of the ions in the ion beam are incident on the reflective electrode 13 is reflected, so that it is on the other detector 14a . 14b fall. Conversely, an ion beam that is not uniform across the collector slot three is distributed and / or not symmetrical about the center of the collector slot three is distributed from the electrode 13 divided unevenly, so that the signals from the two detectors 14a . 14b are significantly different.

According to the preferred embodiment, the collector slot three accurately positioned so that only analyte ions of interest across the collector slot three be distributed and / or symmetrically around the center of the collector slot three be distributed. Accordingly, only analyte ions of interest become uniform and / or symmetric across the reflective electrode 13 distributed, so that essentially 50% of the analyte ions of interest to one of the detectors 14a . 14b while substantially 50% of the analyte ions are on the other detector 14a . 14b fall. However, interference ions pass through the magnetic sector mass analyzer on slightly different trajectories and therefore do not become uniform or symmetric across the collector slot three distributed. Accordingly, the interference ions do not become uniform or symmetrical across the reflective electrode 13 distributed so that the interference ions between the two detectors 14a . 14b not distributed equally. It therefore follows that the ion signals from the two detectors 14a . 14b are significantly different. It is therefore by measuring the relative intensity of the signals from the two detectors 14a . 14b possible to determine if the total ion beam across the collector slot three is evenly distributed and / or whether the ion beam around the center of the collector slot three is distributed symmetrically. This in turn makes it possible to determine whether the detected ion beam has a significant amount of interference ions. If the signals from the two ion detectors 14a . 14b are substantially identical, they can be summed and recorded, and otherwise the signals can be ignored or discarded. Alternatively, the signals from the two ion detectors may be summed and multiplied by a weighting factor, preferably in the form exp (-ky ⁿ ), where k is preferably 1, n is preferably 2 and y is the standard deviation of the total number from the first and the second second detector during a time t detected ions. The weighting factor preferably has the effect of maintaining the significance of the summed signals when the signals are substantially similar, and of attenuating or otherwise significantly reducing the significance of the summed signals if the signals differ substantially in intensity.

The reflective electrode 13 preferably includes a blade electrode with a fine edge or a wedge-shaped electrode. The reflective electrode 13 is preferably substantially perpendicular to the plane of the collector slot three and disposed substantially parallel to the direction of the magnetic fields so as to divide the ion beam in the direction of mass dispersion. The ion beam is preferably subdivided into two separate ion beams, which are then placed on two or more detectors 14a . 14b be directed. A high voltage with respect to the ion source is preferably applied to the reflective electrode 13 applied so that ions from the reflective electrode 13 be repelled and depending on which side of the dead center of the blade electrode 13 the ions are located and are directed to bounce off to one side or the other. Adjusting the ion beam and / or the reflective electrode 13 is preferably possible, so that the ion beam with the center of the collector slot three can be aligned and the ions in the center of the ion beam exactly on the beam splitter edge of the reflective electrode 13 be directed. All ions entering the split ion detector 11 run, are preferably to one or the other side of the reflective electrode 13 deflected so that the ions from two or more detectors 14a . 14b be detected.

Ions preferably pass through an Ab shielding tube 12 (as in 4 is shown) in the divided ion detector 11 and come out of the shield tube 12 out, making it the reflective electrode 13 preferably directly opposite. The shielding tube 12 preferably effects at least partial and preferably substantial shielding by the split ion detector 11 current ions from any electric fields resulting from voltages applied to the detectors 14a . 14b be created. The of the reflective electrode 13 generated delaying electric fields cause the ions to bounce off and to the two or more detectors 14a . 14b be reflected back, on both sides of the shield tube 12 are arranged. The two detectors 14a . 14b preferably have microchannel plates with anodes, which are arranged behind the microchannel plates. Any ion that arrives at one of the microchannel plates will produce an ion pulse that is emitted so that the electrons on the anode are received behind the microchannel plate. Any ion pulse falling on the anode can be counted or integrated and then measured using an analog-to-digital converter. The ion detectors 14a . 14b For example, discrete dynode electrons may have multiple or continuous dynode channeltrons, as described in more detail below.

5 shows in greater detail the portion of the mass spectrometer between the collector slot three and the split ion detector 11 according to an embodiment of the present invention. A lens 9 is preferably downstream of the collector slot three and upstream of the split ion detector 11 provided. The Lens 9 refocuses the image of the collector slot three preferably to the input of the split ion detector 11 , Preferably, the refocused image of the collector slot becomes three magnified to increase the spatial distribution of the ions passing through the collector slot three run and split ion detector 11 Arrive.

6 shows a particularly preferred embodiment of the present invention, wherein of the reflective electrode 13 reflected ions to two conversion dynodes 15a . 15b and be sped up on this. Ions pointing to the conversion dynodes 15a . 15b fall, cause the conversion dynodes 15a . 15b Generate secondary electrons. The resulting secondary electrons are then detected using two detectors 14a . 14b which preferably include microchannel plate ion detectors. An advantage of using conversion dynodes 15a . 15b For initially detecting the ions in place of the microchannel plates, the effectiveness of ion detection can be increased to nearly 100%. A microchannel plate typically has an effective ion-receiving area of 60-70% at which an incident ion results in the generation of secondary electrons. Therefore, the ion detection efficiency of a microchannel plate is effectively limited to about 60-70%. On the other hand, the conversion dynodes have 15a . 15b an ion detection efficiency of about 100% and typically provide between two and six electrons per each conversion dynode 15a . 15b incident ion. Accordingly, the probability that the as in 6 represented arranged microchannel plates 14a . 14b detecting at least one of the secondary electrons responsive to an ion being directed to the conversion dynode 15a . 15b comes from the conversion dynodes 15a . 15b generated and released, practically 100%.

In another less preferred embodiment, ions may be from the conversion dynodes 15a . 15b are accelerated and received on one or more scintillators and / or one or more phosphors (not shown). The resulting photons may then preferably be detected using one or more photomultiplier tubes ("PMT") and / or one or more solid state photosensitive detectors (not shown).

7 shows a further embodiment, wherein two detectors 14a . 14c respectively. 14b . 14d on each side of the reflective electrode 13 are arranged so that a total of four ion detectors are provided. According to this embodiment, a part of the ion beam which is on one side of the central reflective electrode 13 is deflected to two ion detectors 14a . 14c receive. Similarly, the one on the other side of the central reflective electrode 13 deflected part of the ion beam on two other detectors 14b . 14d receive. This embodiment enables asymmetry of the ion beam with respect to the reflective electrode 13 (and thus the collector slot three ) is determined more accurately. It is contemplated that six, eight, ten, twelve or any other number of other ion detectors may be provided in accordance with further embodiments not shown.

8th shows another embodiment wherein the preferred split ion detector 11 downstream of a second detector system 16 . 17 . 18 is provided. The second detector system 16 . 17 . 18 is preferably provided outside the axis of the ion beam so that neutral particles in the ion beam are preferably the second detector system 16 . 17 . 18 do not bother.

According to this embodiment, the upstream ion detector preferably a conversion dynode 16 , one or more focusing ring electrodes 17 , a scintillator (or a phosphor) and a photomultiplier 18 on. When the voltages applied to the second detector system are switched off, the ions travel without interruption directly past the second detector system to the preferred split ion detector 11 , When the voltages applied to the second detector system are turned on, ions are preferably applied to the conversion dynode 16 distracted. Ions fall on the conversion dynode 16 and cause secondary electrons to be triggered, which are then preferably through the one or more ringlets 17 on the scintillator or phosphor 18 be accelerated and focused. Alternatively, the ions may be deflected directly onto a microchannel plate detector (not shown).

According to an alternative embodiment, the preferred split ion detector 11 and the second detection system 16 . 17 . 18 be arranged so that ions are directed by an electrostatic and / or magnetic field on one or the other of the two detectors.

In a further embodiment, in an operating mode, substantially all of the ions may be applied to one of the detectors by an electric and / or magnetic field 14a . 14b . 14c . 14d of the preferred shared ion detector 11 be directed.

When an ion beam having ions with a specific mass-to-charge ratio crosses the collector slot three is scanned, the resulting signal profile is commonly referred to as the detector profile. When the ion beam over the collector slot three When ions are scanned, ions begin to be passed to the ion detector when the leading edge of the ion beam is the first edge of the collector slit three reached. Ions then continue through the collector slot three and to the ion detector until the trailing edge of the ion beam at the second opposite edge of the collector slot three arrives. Accordingly, the width of the tip profile is the width w _{b of} the ion beam summed with the width w _{c of} the collector slot. If the width w _{b of} the ion beam is substantially equal to the width w _{c of} the collector slot three is, the peak profile corresponding to the case has a maximum in which the ion beam is symmetrical about the center of the collector slot three is distributed. The tip profile changes depending on the relative width W _b of the ion beam and the width w _c of the collector slit three , The peak profile also changes depending on the intensity profile of the ion beam.

High resolution recording measurements of selected ions, as described above for the detection of traces of 2,3,7,8-tetrachlorinated dibenzo-p-dioxin, are commonly carried out at a mass resolution of 10,000 (10% valley definition). A mass peak with a width of 100 ppm of mass, when measured at 5% of maximum intensity, has a mass resolution of 10,000 (10% valley definition). A mass tip 100 ppm wide, usually comprises a maximum transmission when the collector slit width w _c is just equal to that of the ion beam width w _B, ie, when the collector slit three and the ion beam each have a width of 50 ppm. Under these conditions, the source slot width w _{s is} as large as it can be, hence the collector slot three just the entire at the collector slot three Incoming beam passes and thus the peak width (w _b + w _c ) is 100 ppm.

9 shows an example of the tip profile P obtained when an ion beam B having a width w _b of 50 ppm over a collector slot three with a width w _c of 50 ppm is scanned. The resulting observed peak profile P has a width of 100 ppm and has a maximum corresponding to the case where the ion beam at the collector slot three is centered. The ion beam profile B is at one at the collector slot three centered position shown. The ion beam profile B may vary according to a number of parameters in the design of the mass spectrometer, although a typical beam profile may follow a cosine distribution. In the in 9 As shown, the ion beam profile B has a cosine distribution, and the resulting observed peak profile P detected by a conventional single ion detector has a cosine square distribution.

In high resolution ion-bombardment experiments, the ion beam is switched to a central position where substantially 100% of the ion beam is transmitted by a collector slot of the mass spectrometer. Because the ion beam is not scanned across the collector slot, this method does not allow knowledge about the tip profile to be obtained. It can only be assumed that the peak profile is that represented by P in 9 is shown. If the peak profile is not what is expected, for example because the peak does not have the exact mass-to-charge ratio, or because the peak has the measurement of randomly scattered ions with very slightly different mass-to-charge ratios, this is not known and the interference ions are included in the measurement of the analyte ions. However, if the ion beam transmitted by the collector slit is decomposed into two or more ion beams, the two or more detectors are detected, as is the case in the preferred embodiment, the situation is quite different, as will be shown in greater detail below.

10 shows an example of the peak profiles P ₁ , P ₂ , P _sum observed when an ion beam having a profile B and a width w _b of 50 ppm is applied to a collector slot three with a width w _c of 50 ppm and using a split ion detector 11 is detected according to the preferred embodiment. Those on the two detectors of the preferred split ion detector 11 recorded resulting peak profiles P ₁ , P ₂ are each 75 ppm wide and shifted by 25 ppm to each other. If the two peak profiles P ₁ , P _{2 are} summed, the resulting peak profile P _{sum is} 100 ppm wide and is essentially the same profile as that recorded on a conventional single ion detector, as in FIG 9 is shown.

In a high-resolution ion-selected recording experiment in which the ion beam is switched to the central position, this is on each of the two detectors of the preferred split ion detector 11 recorded ion signal is essentially the same, provided that the ion beam around the center of the collector slot three is arranged symmetrically. However, if the peak profile is not as expected, for example, because the ions include scattered interference ions with slightly different mass-to-charge ratios or because the ions include randomly scattered ions with similar mass-to-charge ratios, those of the two preferred ion detector splitters are 11 detected ion signals are not equal. Therefore, the split ion detector allows 11 according to the preferred embodiment, a determination of whether (and indeed to what extent) interference ions are detected along with the desired analyte ions and therefore whether the ion signal is reliable. If the ion beam is also substantially free of the presence of interference ions, the ion signals from the two detectors are substantially the same, and it can be inferred with a high degree of confidence that the analyte ions provided are detected without unwanted interference ions measuring the intensity of the ions Influence analyte ions.

It is based 10 be seen that when the ion beam is switched to the central position, each detector of the preferred split ion detector 11 does not detect the maximum number of ions it would detect if the ion beam were shifted by 12.5 ppm. The ion beam is therefore not at the top of the two detectors of the preferred split ion detector 11 even if it is located at the uppermost peak of the peak profile P _sum for the sum of the peak profiles P ₁ , P _{2 of} the individual detectors. This means that a very small shift in the position of the ion beam causes the signal on one of the detectors to increase while the signal on the other detector decreases simultaneously. Therefore, the preferred split ion detector is 11 very sensitive to small shifts in the position of the ion beam and to the presence of interference ions.

The effect of a small shift in the position of the ion beam will be further described with reference to FIG 11 shown. It will be at the in 11 shown in the table that the resolution of the preferred ion detector 11 10000 (10% valley definition) and that only 20 ions from the collector slot three and subsequently from the preferred shared ion detector 11 be detected. In this illustration, the ion beam and collector slot have three both a width of 50 ppm, resulting in an observed peak profile width of 100 ppm.

In column 1 of 11 For example, a series of shifts in the ion beam away from the center of the collector slot are tabulated in ppm units. In column 2, the corresponding numbers of ions are tabulated at the first detector of the preferred split ion detector 11 for the corresponding shift in the ion beam, which is detailed in column 1, would be detected. Similarly, in column 3, the number of ions detected on the second detector are tabulated for the same corresponding displacement in the ion beam.

In column 4, the total number of ions detected by the first and second detectors, that is, the sum of columns 2 and 3, is arranged in a table. It can be seen that the total number of ions detected decreases as the position of the ion beam is increasingly shifted from the center. This is because the ion beam and the collector slot three have the same width and that when the ion beam is moved from the center, not all ions in the ion beam onto the collector slot three fall and therefore not all ions are forwarded.

Column 5 tabulates the average number of ions that would have been expected to be detected on each of the first and second detectors if the ion beam were in the center given the total number of ions indicated in column 4. In other words, column 5 simply gives half of the Ge for each value of ion beam shift total number of ions indicated in column 4. In column 6, a standard deviation for the expected ion count is tabulated for each of the first and second detectors indicated in column 5.

In Column 7 is the difference between that given in column 2 actual Number of ions for the first detector and the number of ions expected by column 5 would have been expressed by the number of standard deviations of those in column 6 in tabular form arranged expected number of ions, arranged in tabular form. In Column 8 is similar the difference, expressed in standard deviations, between the actual values given in column 3 Number of ions for the second detector and that expected in column 5 Number, again expressed by the number of standard deviations arranged in tabular form in column 6 the expected number of ions, arranged in tabular form.

In Column 9 is the percentage probability P1 for the difference the number of ions from the expected average arranged in tabular form, the smaller or equal to the actual Difference of for the first detector in column 7, assuming the number of ions a natural one Distribution or Gauss distribution is. Similarly, column 10 is the same percentage probability P2 for the difference that for the second Detector in column 8 indicated number of ions arranged in tabular form. Therefore, in columns 9 and 10, the percent probabilities are for the Observing measurements within the relative ranges given in columns 7 and 8, respectively Standard deviations given, with an ion beam with the in Column 4 indicated number of electrons centered on the collector slot is. After all in column 11 is the combined percentage probability P for both watching a measurement outside the relative standard deviation given in column 7 as well a measurement outside the relative standard deviation given in column 8 in tabular form arranged. In other words, in column 11, the percentage Probability of observing at the first detector and at the second detector for a peak with a total ion number that is the sum of the two is equal to separate ion numbers, which is centrally positioned, recorded two ion numbers.

How out 11 As can be seen, the ion counts on the two detectors are corresponding to an ion beam having only 20 ions, with the ion beam shifted by only 5 ppm, such that the likelihood that the observed numbers of ions can be observed if the ion beam is centrally positioned , only about 13%. Furthermore, the ion counts on the two detectors are from an ion beam having only 20 ions, with the ion beam shifted by 10 ppm, such that the probability that the observed numbers of ions can be observed, if the ion beam is centrally positioned, is only 1 %. Similarly, if the ion beam is shifted by 15 ppm, the probability of the observed numbers of ions being observed if the ion beam is centrally positioned is only 0.1%.

It is obvious in this example that the advantage of using a split ion detector according to the preferred embodiment is that for the measurement of an ion beam having only 20 ions a security of 99% guaranteed could be that the mass tip observed no disturbing peak which is due to that the ion beam is shifted by only 10 ppm. It could alternatively with a 99.9% certainty that the observed mass tip is not a disturbing mass peak, the is due to that the ion beam is shifted by 15 ppm.

On the other hand would it be when using a conventional Ion detector required, with a mass peak width at 5% the height of about 20 ppm to get the same specification. This would a very high resolution of about 50,000 (10% valley definition) as opposed to 10,000 in the preferred one embodiment correspond. It is therefore apparent in this example that the divided ion detector according to the preferred embodiment, compared with a comparable conventional ion detector, in about a fivefold increase of specificity provides.

alternative For example, the preferred shared ion detector may be considered to provide the same specificity but being more sensitive between 5 and 25 times, because this is the likely sensitivity loss that is from a fivefold increase the resolution of the mass spectrometer from 10,000 to 50,000 (10% valley definition).

12 shows another example of the effect of small shifts in the position of an ion beam incident on a preferred ion detector. The resolution of the preferred ion detector was reduced to 2000 in this example (10% valley definition). It has thus been assumed that the transmission has been increased by a factor of five, so that the total number of ions detected by the preferred shared ion detector has risen to 100. In this illustration, the width of the ion beam and the width of the collector slot three both 250 ppm resulting in a peak width of 500 ppm. It is based 12 he It can be seen that the ion counts on the two detectors resulting from the ion beam being displaced 20 ppm from the center are such that the likelihood that the observed numbers of ions could be observed if the ion beam is centered on the collector slit was only 1. This example illustrates the advantage of using a split ion detector according to the preferred embodiment, because for the measurement of a peak corresponding to 100 ions at a resolution of 2000 (10% valley definition) with a confidence of 99%, it was possible to ensure that the peak was no longer 20 ppm shifted spiky peak. In contrast, using a conventional ion detector, it would be necessary to work with a peak width at 5% of the level of 40 ppm to achieve the same specificity. This corresponds to a high resolution of 25000 (10% valley definition) compared to a resolution of only 2000 according to the preferred embodiment. It also follows that the preferred split ion detector achieves both increased sensitivity and increased specificity as compared to that achievable with a conventional ion detector operating at a resolution of 10,000 (10% valley definition).

It It has been shown that the split ion detector according to the preferred embodiment either the specificity improve the mass analysis without a loss of sensitivity or improved sensitivity without loss of specificity can provide or actually both improved sensitivity and improved specificity can provide. Furthermore you can fortuitously scattered ions representing background noise, at least in part, if not to a considerable extent be eliminated.

Claims (40)

Magnetic sector mass spectrometer comprising: - a magnetic sector mass analyzer; - a collector slot ( three ) disposed downstream of the magnetic sector mass analyzer; A device ( 13 ) located downstream of the collector slot ( three ) is arranged around one of the collector slot ( three ) to divide the transmitted ion beam into at least a first and a second ion beam; At least a first detector ( 14a . 14c ) for measuring the intensity of at least a portion of the first ion beam; At least one second detector ( 14b . 14d ) for measuring the intensity of at least a portion of the second ion beam; wherein the collector slot ( three ) is arranged so that analyte ions of interest in the ion beam uniformly across the collector slot ( three ) and / or symmetrically around the center of the collector slot ( three ) are distributed; the device ( 13 ) is arranged so that essentially half of the analyte ions in the ion beam are applied to the at least one first detector ( 14a . 14c ) and the other half of the analyte ions in the ion beam onto the at least one second detector ( 14b . 14d ) falls; and a processor for determining the intensity of the at least one portion of the first ion beam with respect to the intensity of the at least one portion of the second ion beam. Magnetic sector mass spectrometer according to claim 1, wherein the magnetic sector mass spectrometer is a simple focusing Magnetic sector mass spectrometer is. Magnetic sector mass spectrometer according to claim 1, wherein the magnetic sector mass spectrometer is a double-focusing Magnetic sector mass spectrometer is. Magnetic sector mass spectrometer according to one of the preceding claims, wherein the device ( 13 ) has an electrode which causes ions to be applied to the at least one first and the at least one second detector ( 14a . 14b . 14c . 14d ) reflected or distracted. Magnetic sector mass spectrometer according to claim 4, wherein the electrode ( 13 ) has a sheet with a fine edge. Magnetic sector mass spectrometer according to claim 4 or 5, wherein the electrode ( 13 ) is a wedge-shaped electrode. Magnetic sector mass spectrometer according to one of the preceding Claims, which further comprises an electron impact ion source ("EI ion source"). Magnetic sector mass spectrometer according to one of claims 1 to 6 further comprising a chemical ionization ion source ("CI ion source"). A magnetic sector mass spectrometer according to any one of claims 1 to 6, further comprising an ion source selected from the group consisting of (i) an electrospray ion source ("ESI ion source"), (ii) an atmospheric pressure ion source with chemical ionization ("APCI ion source"), (iii) an atmospheric pressure photoionization ion source ("APPI ion source"), (iv) a matrix assisted laser desorption ionization ion source ("MALDI ion source"), (v) a laser desorption ionization ion source (" LDI ion source "), (vi) an inductively coupled plasma ion source (" ICP-Io (vii) a fast atom bombardment ion source ("FAB ion source"), (viii) a liquid secondary ion mass spectrometry ion source ("LSIMS ion source"), (ix) a field ionization ion source ("FI"). Ion source ") and (x) a field desorption ion source (" FD ion source "). Magnetic sector mass spectrometer according to one of the preceding Claims, which further has a continuous ion source. Magnetic sector mass spectrometer according to one of claims 1 to 9, which further comprises a pulsed ion source. Magnetic sector mass spectrometer according to one of the preceding claims, which further comprises a downstream of the collector slot ( three ) arranged lens ( 9 ) having. Magnetic sector mass spectrometer according to claim 12, wherein the lens ( 9 ) the image of the collector slot ( three ) on the device ( 13 ) refocused. Magnetic sector mass spectrometer according to claim 12, wherein the lens ( 9 ) collimates the ion beam. Magnetic sector mass spectrometer according to one of the preceding claims, which further comprises a shielding tube ( 12 ) between the collector slot ( three ) and the device ( 13 ) and the ion beam opposite to the at least one first ( 14a . 14c ) and / or the at least one second detector ( 14b . 14d ) shields applied voltages. Magnetic sector mass spectrometer according to one of the preceding claims, wherein the at least one first ( 14a . 14c ) and / or the at least one second ( 14b . 14d ) Detector has one, two, three, four, five, six, seven, eight, nine, ten or more than ten microchannel plate detectors. Magnetic sector mass spectrometer according to one of the preceding claims, wherein the at least one first ( 14a . 14c ) and / or the at least one second ( 14b . 14d ) Detector one, two, three, four, five, six, seven, eight, nine, ten or more than ten conversion dynodes ( 15a . 15b ) for generating electrons in response to ions falling on the conversion dynode (s). Magnetic sector mass spectrometer according to claim 17, which further comprises one or more electron multipliers and / or one or more microchannel plate detectors for detecting the conversion dynode ( 15a . 15b ) or the conversion dynodes ( 15a . 15b ) has generated electrons. Magnetic sector mass spectrometer according to claim 17, which further comprises one or more scintillators and / or one or more phosphors, of which the conversion dynode or the conversion dynodes ( 15a . 15b ) and wherein the one or more scintillators and / or the one or more phosphors produce photons in response to receiving electrons. Magnetic sector mass spectrometer according to claim 19, which further comprises one or more photomultiplier tubes and / or one or more photosensitive solid state detectors for detecting having the photons. Magnetic sector mass spectrometer according to one of the preceding claims, which further comprises an additional detector ( 16 . 17 . 18 ) which upstream of the at least one first ( 14a . 14c ) and the at least one second ( 14b . 14d ) Detector is arranged. Magnetic sector mass spectrometer according to claim 21, wherein the additional detector ( 16 . 17 . 18 ) a conversion dynode ( 16 ) having. Magnetic sector mass spectrometer according to claim 22, which further comprises one or more electron multipliers and / or one or more microchannel plate detectors for receiving the conversion dynode ( 16 ) has generated electrons. Magnetic sector mass spectrometer according to claim 22, which further comprises one or more scintillators and / or one or more phosphors on which the conversion dynode ( 16 ), wherein the one or more scintillators and / or the one or more phosphors generate photons in response to receiving electrons. The magnetic sector mass spectrometer of claim 24, further comprising one or more photomultiplier tubes ( 18 ) and / or one or more photosensitive solid state detectors for detecting the photons. Magnetic sector mass spectrometer according to one of the preceding claims, wherein the gain of the at least one first ( 14a . 14c ) and / or the at least one second ( 14b . 14d ) Detector can be set independently. Magnetic sector mass spectrometer according to claim 26, wherein the at least one first ( 14a . 14c ) and the at least one second ( 14b . 14d ) Detector powered by independently adjustable power supplies. Magnetic sector mass spectrometer according to one of the preceding claims, wherein the at least one first ( 14a . 14c ) and the at least one second ( 14b . 14d ) Detector further comprise one or more analog-to-digital converters and / or one or more Ionenzähldetektoren. Magnetic sector mass spectrometer according to one of the preceding claims, further comprising adjusting means for centering the ion beam on the device ( 13 ) having. A method of mass spectrometry, comprising the steps of: - passing an ion beam through a magnetic sector mass analyzer and a collector slot located downstream of the magnetic sector mass analyzer ( three ), - splitting the ion beam downstream of the collector slot ( three ) into at least a first and a second ion beam such that substantially half of the analyte ions in the ion beam are directed onto at least one first detector ( 14a . 14c ) and the other half of the analyte ions in the ion beam fall on at least one second detector ( 14b . 14d ), measuring the intensity of at least part of the first ion beam with the at least one first detector ( 14a . 14c ), Measuring the intensity of at least part of the second ion beam with the at least one second detector ( 14b . 14d ), wherein the intensity of the at least a portion of the first ion beam is determined with respect to the intensity of the at least a portion of the second ion beam. A method of mass spectrometry according to claim 30, wherein the at least one first ( 14a . 14c ) and the at least one second ( 14b . 14d ) Detector simultaneously measure the intensities of at least a portion of the first and second ion beams. Method for mass spectrometry according to one of claims 30 to 31, wherein when the intensity of at least a part of the first and / or second ion beam by ≥ x% of the intensity at least a part of the second ion beam is different, found is that the ion beam a significant amount of interference ions where x is selected from the following group: (i) 1, (ii) 2, (iii) 3, (iv) 4, (v) 5, (vi) 6, (vii) 7, (viii) 8, (ix) 9, (x) 10, (xi) 15, (xii) 20, (xiii) 25, (xiv) 30, (xv) 35, (xvi) 40, (xvii) 45, (xviii) 50, (xix) 55, (xx) 60, (xxi) 65, (xxii) 70, (xxiii) 75, (xxiv) 80, (xxv) 85, (xxvi) 90, (xxvii) 95 and (xxviii) 100th A method of mass spectrometry according to any one of claims 30 to 32, wherein, when within a time t, the number of said at least one first detector ( 14a . 14c ) detected ions from the number of the at least one second detector ( 14b . 14d ) detected ions by ≥ y standard deviations of the total number of the first ( 14a . 14c ) and the second ( 14b . 14d ) Detector during the time t detected ions, it is determined that the ion beam has a significant amount of interference ions, where y is selected from the group: (i) 0.25, (ii) 0.5, (iii) 0 , 75, (iv) 1.0, (v) 1.25, (vi) 1.5, (vii) 1.75, (viii) 2.0, (ix) 2.25, (x) 2, 5, (xi) 2.75, (xii) 3.0, (xiii) 3.25, (xiv) 3.5, (xv) 3.75, (xvi) 4.0 and (xvii)> 4, 0th A method of mass spectrometry according to any one of claims 30 to 33, further comprising: signals from the at least one first ( 14a . 14c ) and of the at least one second ( 14b . 14d ) Detector to generate a combined signal, and the combined signal is multiplied by a weighting factor. A method of mass spectrometry according to claim 32 or 33, further comprising: signals from said at least one first ( 14a . 14c ) and of the at least one second ( 14b . 14d ) Are combined to produce a combined signal, and the combined signal is multiplied by a weighting factor which (i) does not significantly attenuate the combined signal when the signal is received from the at least one first detector (Fig. 14a . 14c ) substantially the signal from the at least one second detector ( 14b . 14d ) and / or (ii) significantly attenuates the combined signal as the signal from the at least one first detector ( 14a . 14c ) significantly from the signal from the at least one second detector ( 14b . 14d ) is different. A method of mass spectrometry according to claim 35, wherein the weighting factor is of the form exp (-ky ⁿ ), where k and n are constants, and wherein within a time t the number of the at least one first detector ( 14a . 14c ) detected ions from the number of the at least one second detector ( 14b . 14d ) detected ions by y standard deviations of the total number of the at least one first ( 14a . 14c ) and of the at least one second ( 14b . 14d ) Detector during the time t detected ions differs. Method for mass spectrometry according to claim 36, wherein k is selected from the following group: (i) 0.5-2.0, (ii) 0.6-1.8, (iii) 0.7-1.6, (iv) 0.8-1.4, (v) 0.9-1.2, (vi) 0.95-1.1 and (vii) 1. Method for mass spectrometry according to claim 36 or 37, where n is selected from the following group: (i) 1.0-3.0, (ii) 1,2-2,8, (iii) 1.4-2.6, (iv) 1.6-2.4, (v) 1.8-2.2, (vi) 1.9-2.1 and (vii) 2. A method of mass spectrometry according to any one of claims 32 or 33 and 35 to 38, wherein, if it is determined that the ion beam has a significant amount of interference ions, signals from the at least one first ( 14a . 14c ) and / or of the at least one second ( 14b . 14d ) Detector may be rejected or otherwise considered inaccurate. A method of mass spectrometry according to any one of claims 32 or 33 and 35 to 39, wherein, if it is determined that the ion beam does not have a significant portion of interference ions, signals from the at least one first ( 14a . 14c ) and of the at least one second ( 14b . 14d ) Detector can be summed or otherwise considered accurate.