JPWO2012124041A1 - Ion guide and mass spectrometer - Google Patents

Abstract

The curved ion guide (40) installed in the cell chamber (43) of the collision cell (4) includes four curved rod electrodes (412, 414) disposed around the curved central axis O. And a curved cylindrical resistor (42) surrounding the curved rod electrode. A high frequency voltage is applied to the four curved rod electrodes, and different DC voltages are applied to the inlet side end and the outlet side end of the resistor. As a result, a DC electric field for deflection is formed in the space surrounded by the curved rod electrode, which is superimposed on the high frequency electric field for ion focusing and attracts ions to the inside of the curve. It becomes weaker from the side toward the exit side. The ions introduced into the collision cell are dissociated by contact with the CID gas, so the kinetic energy of the ions decreases as the ions progress. It is possible to efficiently guide ions to the ion guide outlet while avoiding the excess.

Description

  The present invention relates to an ion guide for transporting ions while converging them, and more specifically, an ion guide suitable for being disposed inside a collision cell for cleaving ions, and a mass spectrometer using the ion guide About.

  The triple quadrupole mass spectrometer includes a front quadrupole mass filter (so-called Q1) and a post-quadrupole mass filter (so-called Q3) having a function of separating ions according to the mass-to-charge ratio m / z. In the meantime, a collision cell for cleaving ions is provided, and ions (precursor ions) having a specific mass-to-charge ratio selected in the preceding quadrupole mass filter are cleaved in the collision cell, and various kinds of ions generated thereby Among the product ions, ions having a specific mass-to-charge ratio can be selected and detected by the subsequent quadrupole mass filter. Generally, in a triple quadrupole mass spectrometer, a front quadrupole mass filter, a collision cell, and a rear quadrupole mass filter are arranged in series. In comparison, the overall size of the device is considerably increased.

  In order to reduce the apparatus size in a triple quadrupole mass spectrometer, the apparatus described in Patent Document 1 has a shape in which a collision cell is curved by approximately 180 ° (a shape in which an annulus is cut in half by a diameter). ). As a result, the ion introduction direction to the collision cell and the ion derivation direction from the collision cell are opposite to each other, so that the front quadrupole mass filter and the rear quadrupole mass filter can be arranged close to each other. It becomes possible, and the whole apparatus can be stored compactly. In this apparatus, a high-frequency voltage is applied to a curved ion guide (so-called q2) disposed in the collision cell in the same manner as a general linear ion guide. While the ions are converged by the action, the ions are transported while being curved along the electric field axis.

  However, since ions introduced into the collision cell are given a large collision energy (kinetic energy) of several tens of eV, it is difficult to curve the ion trajectory only by the restraining action by the high-frequency electric field. Therefore, in the apparatus disclosed in Patent Document 1, ions are caused to fly linearly for a certain length in the vicinity of the collision cell entrance, and collision induced dissociation (CID) is performed in that portion to move the ions. The energy is attenuated, and the trajectory of the relatively low energy product ions generated by the CID is bent by the action of the high frequency electric field. However, even if the kinetic energy of ions is lowered to some extent, it is not easy to bend the ion trajectory greatly by the action of only the high-frequency electric field, and the ion convergence efficiency and transport efficiency are not so high. Therefore, the detection sensitivity is low. In addition, since it is necessary to provide a linear portion having a certain length at the entrance portion of the collision cell, the collision cell itself becomes large, and the effect of reducing the apparatus size is also reduced.

  By the way, as a general ion guide for transporting ions to a subsequent stage using a high-frequency electric field, a curved ion guide using a curved rod electrode, which is particularly intended to remove neutral particles, is known. (Refer to patent document 2 etc.).

  FIG. 10 is a schematic perspective view of an example of a curved ion guide. As shown in the figure, the ion guide 40 includes four curved rod electrodes 401, 402, 403, and 404, and ions derived from the sample travel while bending along the shape of the ion guide 40 due to the influence of the high-frequency electric field, Since neutral particles having no electric charge are not affected by the high-frequency electric field, they travel straight through the ion guide 40 and are discharged to the outside of the ion guide 40 or come into contact with the curved rod electrodes 401 to 404. To be removed.

  Since the ions introduced into the ion guide 40 have a certain amount of kinetic energy, it is actually difficult to bend along the curved path while focusing the ions only by the high-frequency electric field. Therefore, in the curved ion guide described in Patent Document 2, not only the rod electrode itself has a curved shape, but also the curved rod electrode or a direct current for deflection on an electrode provided separately from the curved rod electrode. By applying a voltage, a DC electric field that applies a force that bends ions inwardly in the curved path (in the direction of arrow R in FIG. 10) is formed in a space surrounded by the curved rod electrode.

11 and 12 are configuration diagrams of a curved rod electrode and auxiliary electrode and a circuit block that applies a voltage to these electrodes in Patent Document 2. FIG. FIG. 11 shows a configuration in which an auxiliary electrode is not provided, and a white arrow in the drawing indicates the inside of the curved path of the curved ion guide 40 (in the radial direction and the inner circumferential direction of the curved central axis that is a part of the arc). ). The voltage sources 601 to 604 apply a high-frequency voltage V _RF to the two curved rod electrodes 402 and 404 facing each other among the four curved rod electrodes 401 to 404, and the other two curved rods. A high frequency voltage −V _RF having the same amplitude and the opposite polarity is applied to the electrodes 401 and 403. Thereby, in the space surrounded by the curved rod electrodes 401 to 404, a high-frequency electric field that converges ions while vibrating is formed as described above. In addition, the voltage sources 601 to 604 are opposite in polarity to the ions to be analyzed (positive ions in this example) on the two curved rod electrodes 401 and 402 located on the inner side of the curved path. A DC voltage −V _DEF is applied, and a DC voltage V _DEF having the same polarity as the ions to be analyzed is applied to the two curved rod electrodes 403 and 404 positioned on the outer side of the curved path. As a result, a DC electric field that attracts ions inward of the curved path, that is, in the direction of the white arrow in the figure, is formed in the space surrounded by the curved rod electrodes 401 to 404.

FIG. 12 shows a configuration in which auxiliary electrodes 405 and 406 are provided, and voltage sources 605 and 606 are high-frequency voltages applied to two curved rod electrodes 402 and 404 facing each other among the four curved rod electrodes 401 to 404. V _RF is applied, and a high frequency voltage −V _RF having the same amplitude and opposite polarity is applied to the other two curved rod electrodes 401 and 403. The voltage source 607 applies a DC voltage −V _DEF having a polarity opposite to that of the ion to be analyzed to the auxiliary electrode 405 positioned on the inner side of the curved path, and the voltage source 608 is positioned on the outer side of the curved path. A DC voltage V _DEF having the same polarity as the ions to be analyzed is applied to the auxiliary electrode 406. Thus, as in the configuration of FIG. 11, a DC electric field that attracts ions to the inside of the curved path in a state of being superimposed on a high-frequency electric field that focuses the ions in a space surrounded by the curved rod electrodes 401 to 404. Will be formed.

  As described above, by applying an appropriate deflection direct current voltage to the curved rod electrode or auxiliary electrode, the ion is bent along the curved path of the ion guide 40 and guided to the exit end, thereby improving the ion passing efficiency. Can do. Therefore, it is conceivable that the ion guides arranged in the above-described collision cell also bend the ions using the deflection DC voltage. However, in this case, there are the following problems. That is, in the collision cell, the kinetic energy of the ions changes due to the dissociation of the ions and the contact with the CID gas. When ions dissociate, the energy changes discretely due to mass distribution, and when the ions come into contact with the CID gas, the energy change is generally continuous. In any case, when the entire collision cell is viewed, ions have a large energy near the collision cell entrance, and ions have a small energy near the collision cell exit. Conventional curved ion guides cannot properly bend the trajectories of ions whose energies are significantly different along the axial direction, resulting in excessive bending or conversely insufficient bending. Is difficult to raise.

  Further, the above problem is not limited to the ion guide disposed in the collision cell. For example, in a liquid chromatograph mass spectrometer or the like, ions are supplied together with gas from an atmospheric pressure ion source such as ESI or APCI. The same applies to an ion guide disposed in a vacuum chamber.

US Patent Application Publication No. 2009/0095898 US Patent Application Publication No. 2009/0294663

  The present invention has been made to solve the above-described problems. In a curved ion guide disposed in a collision cell, a low vacuum chamber, or the like, the kinetic energy of ions to be introduced is along the transport direction. The purpose is to achieve high ion transport efficiency even when changing. The purpose of the mass spectrometer according to the present invention is to improve detection sensitivity by using a curved ion guide with improved ion transport efficiency.

The first invention made to solve the above problems is an ion guide for transporting ions along a curved path while converging ions.
a) 2n (n is an integer of 2 or more) curved rod electrodes arranged so as to surround the curved central axis;
b) Voltage applying means for applying a voltage to each of the 2n curved rod electrodes, and any of the 2n curved rod electrodes adjacent to the circumferential direction centering on the curved central axis. High frequency voltage applying means for applying high frequency voltages having opposite polarities to the two curved rod electrodes;
c) Superimposes a high-frequency electric field formed in a space surrounded by the 2n curved rod electrodes, and causes ions in the space to be inside the curved central axis in a plane perpendicular to the curved central axis. A deflecting electric field forming means for generating a DC electric field attracting in a direction and having different electric field strengths along a curved central axis;
It is characterized by having.

  In the first invention, n which is an integer of 2 or more has no theoretical upper limit, but practically n is in the range of about 2 to 4, that is, the curved rod electrode is a quadrupole, hexapole or octupole. It is preferable that it is the structure of these. The same applies to the following inventions.

  In the ion guide according to the first aspect of the present invention, the deflection electric field forming means may be configured such that, of the 2n curved rod electrodes, one curved rod electrode located inside or outside the curved shape is provided. And a DC voltage applying unit that applies DC voltages having different potentials to the ion inlet side end and the outlet side end of the resistor. It can be. The resistor can be, for example, a curved resistor disposed so as to surround one curved rod electrode positioned inwardly or outwardly.

  In the configuration of the above aspect, when DC voltages having different potentials are applied to the ion inlet side end portion and the outlet side end portion of the resistor by the DC voltage applying means, each portion along the longitudinal direction of the resistor is applied. A partial voltage is generated between the two DC voltages, and a DC electric field is generated in the surrounding space by the divided voltage. For example, if the resistivity of the resistor is uniform, an electric field having a potential gradient along the longitudinal direction of the resistor is formed. The force that attracts ions passing through the space surrounded by the 2n curved rod electrodes in the inner direction of the bending depends on the potential of the DC electric field. Therefore, by determining the DC voltage to be applied so that the DC electric field is strengthened on the inlet side of the ion guide and the DC electric field is weakened on the outlet side, the ions have high kinetic energy on the inlet side of the ion guide. Can be bent sufficiently, and on the outlet side of the ion guide, it is possible to bend appropriately by suppressing excessive bending of ions having low kinetic energy. That is, even when the kinetic energy of ions changes in the direction of ion travel, the ions can be appropriately bent and guided to the exit by the action of the electric field in accordance with the kinetic energy at each position.

Further, the second invention made to solve the above problems is an ion guide for transporting ions along a curved path while converging ions.
a) 2n (n is an integer of 2 or more) curved rod electrodes arranged so as to surround the curved central axis, and one of them is located inside the curve or located outside The curved rod electrodes are arranged so that the distance from the curved central axis changes from the ion inlet side end toward the outlet side end; and
b) Voltage applying means for applying a voltage to each of the 2n curved rod electrodes, and any of the 2n curved rod electrodes adjacent to the circumferential direction centering on the curved central axis. High frequency voltage applying means for applying high frequency voltages having opposite polarities to the two curved rod electrodes;
c) Superimposes a high-frequency electric field formed in a space surrounded by the 2n curved rod electrodes, and causes ions in the space to be inside the curved central axis in a plane perpendicular to the curved central axis. The two curved rod electrodes are positioned inwardly or outwardly so as to form a DC electric field that is attracted in the direction and has different electric field strengths along the curved central axis. DC voltage application means for applying a DC voltage to one curved rod electrode;
It is characterized by having.

  In the ion guide according to the second aspect of the present invention, the potential at each portion in the longitudinal direction of one curved rod electrode to which a DC voltage is applied from the DC voltage applying means is the same, but the rod electrode and the curved center Since the distance from the axis is different in each part, the direct current potential on the curved central axis changes along the direction of the axis. By minimizing the separation distance from the curved central axis to the rod electrode at the ion guide inlet end, and maximizing the separation distance from the curved central axis to the rod electrode at the ion guide outlet end Even if ions have high kinetic energy on the entrance side of the guide, they can be bent sufficiently, and on the exit side of the ion guide, ions having only low kinetic energy can be appropriately bent without being bent. That is, even when the kinetic energy of the ions changes in the direction of ion travel, the ions can be appropriately bent and guided to the exit by the action of the electric field in accordance with the kinetic energy at each position.

The third invention made to solve the above problems is an ion guide for transporting ions along a curved path while converging ions.
a) 2n (n is an integer of 2 or more) curved rod electrodes arranged so as to surround the curved central axis, one of which is located inside the curve or located outside 2n curved rod electrodes which are virtual rod electrodes composed of a plurality of electrodes divided in the longitudinal direction;
b) Voltage applying means for applying a voltage to each of the 2n curved rod electrodes, and any of the 2n curved rod electrodes adjacent to the circumferential direction centering on the curved central axis. High frequency voltage applying means for applying high frequency voltages having opposite polarities to the two curved rod electrodes;
c) Superimposes a high-frequency electric field formed in a space surrounded by the 2n curved rod electrodes, and causes ions in the space to be inside the curved central axis in a plane perpendicular to the curved central axis. A plurality of electrodes constituting the virtual curved rod electrode from the ion inlet side end to the outlet side end so as to form a DC electric field attracting in the direction and having different electric field strengths along the curved central axis DC voltage application means for applying different DC voltages toward the part,
It is characterized by having.

  In the ion guide according to the third aspect of the invention, a DC voltage that changes stepwise from the ion inlet side end to the outlet side end is applied from the DC voltage applying means to the plurality of electrodes constituting the virtual curved rod electrode. Then, as in the first and second inventions, the DC potential on the curved central axis changes along the direction of the axis. As a result, even if ions have high kinetic energy at the inlet side of the ion guide, they can be bent sufficiently, and at the outlet side of the ion guide, they can be bent appropriately by suppressing excessive bending of ions having only low kinetic energy. Can do. That is, even when the kinetic energy of the ions changes in the direction of ion travel, the ions can be appropriately bent and guided to the exit by the action of the electric field in accordance with the kinetic energy at each position.

The ion guide according to the first to third inventions has a quadrupole configuration in which n is 2, and the center of the two curved rod electrodes facing each other across the curved central axis is the curved shape. Four curved shapes are positioned such that the center axis is located on a plane on which the central axis is placed, and the centers of the other two curved rod electrodes are located on a curved curved surface that is orthogonal to the plane and includes the curved central axis. A rod electrode is placed,
The DC voltage applying means applies a DC voltage to one of the two curved rod electrodes whose center is located on the plane or a resistor provided along the rod electrodes, A focusing DC voltage having the same polarity as the ions to be analyzed can be applied to the two curved rod electrodes.

  According to the above configuration, in addition to the focusing action by the high-frequency electric field, ions introduced into the space surrounded by the 2n curved rod electrodes, in addition to the DC voltage formed by the curved rod electrodes to which the focusing DC voltage is applied. Depending on the field, a force acts to compress the ions in the vicinity of the curved central axis in a direction orthogonal or oblique to the radial direction in which the ions gradually bend. For this reason, even when ions introduced with a certain degree of kinetic energy travel in a curved shape due to the action of a direct current electric field for deflection, the spread of ions is suppressed and the ions reach the exit end of the ion guide with high efficiency. . Thereby, high ion passage efficiency is realizable.

Moreover, the 4th invention made in order to solve the said subject WHEREIN: In the ion guide which conveys an ion while making it converge,
a) 2n (n is an integer of 2 or more) rod electrodes arranged in parallel to each other so as to surround the linear central axis;
b) Voltage applying means for applying a voltage to each of the 2n rod electrodes, wherein the two high frequency electrodes are opposite in polarity to any two rod electrodes adjacent in the circumferential direction. High-frequency voltage applying means for applying a voltage;
c) Superposed on the high-frequency electric field formed in the space surrounded by the 2n rod electrodes, attracts ions in the space in one direction perpendicular to the central axis, and strengthens the electric field along the central axis. A deflection electric field forming means for forming a deflection electric field for forming a DC electric field of different
It is characterized by having.

  In the ion guide according to the aspect of the fourth invention, the deflection electric field forming means is one resistor arranged so as to extend along a predetermined one of the 2n rod electrodes. And DC voltage applying means for applying DC voltages having different potentials to the inlet side and the outlet side of the ions in the resistor, respectively. The resistor can be, for example, a resistor arranged so as to surround the predetermined one rod electrode.

  In the configuration of the above aspect, when DC voltages having different potentials are applied to the ion inlet side end portion and the outlet side end portion of the resistor by the DC voltage applying means, each portion along the longitudinal direction of the resistor is applied. A partial voltage is generated between the two DC voltages, and a DC electric field is generated in the surrounding space by the divided voltage. For example, if the resistivity of the resistor is uniform, an electric field having a constant gradient potential is formed in the longitudinal direction of the resistor. Without this DC electric field, the central trajectory of the introduced ions coincides with the central axis, but because of the DC electric field, the ions deviate from the central axis as they travel. The force that attracts ions passing through the space surrounded by the 2n rod electrodes in one direction depends on the potential of the DC electric field. Therefore, by determining the DC voltage to be applied so that the DC electric field is strengthened on the inlet side of the ion guide and the DC electric field is weakened on the outlet side, the ions have high kinetic energy on the inlet side of the ion guide. Can be bent, and it is possible to suppress excessive bending of ions having low kinetic energy on the exit side of the ion guide. That is, even when the kinetic energy of ions changes in the direction of ion travel, the ions can be appropriately bent and guided to the exit by the action of the electric field in accordance with the kinetic energy at each position.

  In the ion guides according to the first to fourth inventions, the kinetic energy of ions differs in the direction of travel. Typically, as the ions travel, the kinetic energy attenuates due to contact with surrounding gas. It is suitable for being used in such an environment. That is, the ion guide according to the first to fourth inventions is suitable for an ion guide that is used for the convergence and transport of ions inside a collision cell in which CID gas is introduced to promote dissociation of ions. It is. Further, in a mass spectrometer having one or more intermediate vacuum chambers between an ionization chamber for ionizing sample components under an atmospheric pressure atmosphere and an analysis chamber provided with a mass analyzer, It is also suitable to be disposed inside the intermediate vacuum chamber at the next stage.

  According to the ion guide according to the first to fourth inventions, even when the kinetic energy of the introduced ion changes in the traveling direction of the ion, the ion is appropriately controlled by the action of the electric field according to the kinetic energy at each position. It can be bent and led to the exit. Thereby, high ion transport efficiency can be achieved even in a collision cell or the like that needs to bend the ion trajectory. Thereby, analysis sensitivity and analysis accuracy can be improved.

The schematic block diagram of the ion guide which is one Example (1st Example) of this invention. The perspective view of the curved rod electrode of the ion guide which is 1st Example. The schematic block diagram of the mass spectrometer which used the ion guide which is 1st Example. The schematic block diagram which shows the modification of the ion guide of 1st Example. The schematic block diagram of the mass spectrometer using the ion guide which is another Example (2nd Example) of this invention. The schematic block diagram of the mass spectrometer using the ion guide which is 2nd Example. The schematic block diagram of the mass spectrometer using the ion guide which is another Example (3rd Example) of this invention. The perspective view of the rod electrode of the ion guide which is another Example (4th Example) of this invention. The top view of the rod electrode of the ion guide which is a 4th Example. The perspective view of the curved rod electrode of the conventional curved ion guide. The figure which shows the electrode structure in the conventional curved ion guide, and the circuit structure of a voltage source. The figure which shows the electrode structure in the conventional curved ion guide, and the circuit structure of a voltage source.

  Hereinafter, an ion guide according to the present invention and a mass spectrometer equipped with the ion guide will be described with reference to examples.

[First embodiment]
1 is a schematic configuration diagram of a curved ion guide according to the first embodiment, FIG. 2 is a schematic perspective view of a curved rod electrode of the curved ion guide according to the first embodiment, and FIG. 3 is a mass provided with the curved ion guide. It is a schematic block diagram of an analyzer.

  This mass spectrometer is a triple quadrupole mass spectrometer for dissociating ions between a front quadrupole mass filter 2 and a rear quadrupole mass filter 3 as shown in FIG. A collision cell 4 is arranged. The central axis of the front-stage quadrupole mass filter 2 and the central axis of the rear-stage quadrupole mass filter 3 are substantially orthogonal, and the ion guide installed in the cell chamber 43 of the collision cell 4 substantially follows the trajectory of ions. This is a curved ion guide 40 that bends by 90 °. The sample-derived ions emitted from the ionization unit (ion source) 1 are first introduced into the front quadrupole mass filter 2, where ions having a predetermined mass-to-charge ratio are selected to enter the cell chamber 43 of the collision cell 4. It is sent. The cell chamber 43 is supplied with CID gas. In the cell chamber 43, the ions come into contact with the CID gas and dissociate, whereby various product ions are generated.

  Product ions travel while gradually bending the traveling direction along the curved central axis O of the ion guide 40, reach the outlet end of the ion guide 40, and exit from the cell chamber 43. Neutral particles such as sample molecules introduced into the ion guide 40 together with ions travel straight without being affected by the electric field inside the ion guide 40 and are separated from the ions and excluded. Product ions emitted from the cell chamber 43 are introduced into the subsequent quadrupole mass filter 3, and for example, only product ions having a specific mass-to-charge ratio are selected and reach the detector 5.

  As shown in FIG. 2, the ion guide 40 includes four curved rod electrodes 411 to 414 arranged so as to surround the curved central axis O. Of these, the two curved rod electrodes 412 and 414 have their centers positioned on a plane (corresponding to the paper surface in FIG. 3) on which the curved central axis O, which is a part of an arc, is placed. Further, the other two curved rod electrodes 411 and 413 are positioned at the center on a curved surface which is orthogonal to the plane and includes the curved central axis O. Of the four curved rod electrodes 411 to 414, a curved cylindrical shape is formed so as to surround one curved rod electrode 412 whose center is located on the plane on which the curved central axis O is placed and which is located inwardly of the curve. The resistor 42 is installed. The curved rod electrodes 411 to 414 and the resistor 42 shown in FIG. 1 are end surfaces in a state where the curved rod electrodes 411 to 414 in FIG. 2 are cut along a plane orthogonal to the curved central axis O.

As shown in FIG. 1, the voltage source 612 includes two curved rod electrodes 412 and 414 facing each other among the four curved rod electrodes 411 to 414, a high frequency voltage V _RF and a predetermined DC bias voltage V _BIAS. applying a voltage obtained by superimposing a voltage source 611, the other two predetermined DC bias RF voltage V _RF and amplitude curved rod electrodes 411 and 413 to the high-frequency voltage -V _RF polarity is reversed at the same A voltage superimposed with the voltage V _BIAS is applied. DC bias voltage V _BIAS is a voltage applied in common to all the curved rod electrodes 411 to 414, the DC bias voltage V _{BI AS} itself does not form a direct current electric field inside the ion guide 40. In the examples of FIGS. 11 and 12, the DC bias voltage V _BIAS = 0. As described above, a high-frequency electric field that converges ions while vibrating is formed inside the ion guide 40 by the high-frequency voltages V _RF and −V _RF applied to the curved rod electrodes 411 to 414. This is the same as before.

The voltage source 613 has a polarity opposite to that of the ion to be analyzed (positive ion in this example) at the ion entrance side end of the resistor 42 surrounding the single curved rod electrode 412 located on the inner side of the curved path. The first DC voltage −V _DCin is applied as a deflecting DC voltage, and the ion outlet side end of the resistor 42 has the same polarity as the first DC voltage −V _DCin and the voltage value is higher than | V _DCin |. A small second DC voltage −V _DCout is applied. As a result, a DC electric field is formed in the ion guide 40 to attract ions inward of the curved path, that is, in the direction of the white arrow in FIG. Further, since there is a voltage difference between the DC voltages applied to both ends of the resistor 42, the intensity of the DC electric field on the curved central axis O is greatest at the ion inlet side end, and the outlet side end. It becomes small gradually as it goes to. That is, the action of pulling the ions introduced into the ion guide 40 inward of the curved path is strongest at the entrance end and gradually becomes weaker toward the exit end.

  In order to dissociate ions with high efficiency in the collision cell 4, the ions that have passed through the previous quadrupole mass filter 2 are given large collision energy and are incident on the cell chamber 43. Therefore, ions introduced into the ion guide 40 have a large kinetic energy. Since the cell chamber 43 is filled with the CID gas, the ions come into contact with the CID gas, and a part of the collision energy at this time is converted into internal energy and excited to dissociate the ions. With such dissociation, the kinetic energy that the ions had before dissociation is distributed to a plurality of ions after dissociation. Even when dissociation does not occur, when the ions come into contact with the CID gas, a part of the kinetic energy is taken and lowered. As the ions progress, the chance of contact with the CID gas increases, so the kinetic energy of each ion decreases as it travels deeper.

  Although the kinetic energy of ions is large in the vicinity of the entrance of the ion guide 40, as described above, the action of pulling the ions inward in the curved path is the strongest at the end on the entrance side. Even with strong force, it is pulled inward of the curved path and bends securely. On the other hand, the kinetic energy decreases as the ions travel inside the ion guide 40, but as described above, the action of pulling the ions inward of the curved path gradually weakens. It is pulled inward of the curved path with an appropriate force commensurate with the attenuation, and bends substantially along the curve of the curved central axis O without bending too much. Therefore, even if the kinetic energy of the ions changes due to contact with the CID gas when passing through the ion guide 40, the ions are efficiently guided to the exit of the ion guide 40 by avoiding insufficient or excessive bending of the ions. The light can be emitted from the cell chamber 43. As a result, more ions can be sent to the subsequent quadrupole mass filter 3 than before, and the analysis sensitivity can be improved.

FIG. 4 is a schematic configuration diagram of an ion guide according to a modification of the first embodiment. In this modification, the electrode structure is the same as that of the first embodiment, but the voltage applied to the electrode is slightly different from that of the first embodiment. In other words, in the ion guide 40 according to this modification, the voltage source 614 applies, in addition to the high frequency voltage V _RF and the DC bias voltage V _BIAS , to the two curved rod electrodes 411 and 413 facing each other with the curved central axis O interposed therebetween. In addition, a DC voltage + V _DCy having the same polarity as the ions to be analyzed is applied as a convergence DC voltage. The direct current electric field (convergence direct current electric field) formed in the vicinity of the curved rod electrodes 411 and 413 by applying the converging direct current voltage causes ions in the ion guide 40 to be separated from the curved rod electrodes 411 and 413, respectively. Act on. That is, as indicated by the thick arrows in FIG. 4, since the ions receive a force from the vicinity of the two curved rod electrodes 411 and 413 toward the curved central axis O, the ions are difficult to spread to the outer peripheral side and have a curved center. While converging in the vicinity of the axis O, it is bent as it proceeds by the action of the direct current electric field for deflection by the resistor 42. In the ion guide 40 of the present embodiment, the spreading of ions can be suppressed and the ions can be efficiently transported to the exit end along the curved central axis O by the action of the focusing DC electric field in addition to the high-frequency electric field.

  In the first embodiment and its modification, the resistor 42 has a cylindrical shape that covers one curved rod electrode 412. However, the resistor 42 does not necessarily have to surround the entire circumferential surface of the curved rod electrode 412. A shape in which a part of the surface is notched or a semi-cylindrical shape surrounding only the side facing the curved central axis O may be used.

[Second Embodiment]
FIG. 5 is a schematic configuration diagram of an ion guide according to the second embodiment, and FIG. 6 is a schematic configuration diagram of a triple quadrupole mass spectrometer equipped with the ion guide according to the second embodiment. The same components as those in the above embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the second embodiment, instead of arranging a resistor so as to surround the curved rod electrode arranged in the curved inward direction, the curved curved electrode is inwardly curved out of the four curved rod electrodes 411, 422, 413, 414. The single curved rod electrode 422 is shifted from the normal arrangement so that the distance from the curved central axis O gradually increases toward the outlet side near the curved central axis O on the ion inlet side. It is installed. In FIG. 5, the end of the curved rod electrode 422 is indicated by a dotted line denoted by reference numeral 422 ′ in order to easily understand that the end of the ion exit side of the curved rod electrode 422 is away from the curved central axis O.

  The curved rod electrode 422 is supplied with a high frequency voltage V from a voltage source 623._RFAnd DC bias voltage V _BIASIn addition, the direct current voltage for deflection -V_DCinIs applied. A deflection DC electric field is formed in the internal space of the ion guide 40 by superimposing a high frequency electric field by this deflection DC voltage. As described above, the radial direction from the curved central axis O to the curved rod electrode 422 is formed. The distance is different on the curved central axis O and increases as the ions travel. Therefore, the intensity of the direct current electric field for deflection on the curved central axis O is the largest at the ion inlet side end, and gradually decreases toward the outlet side end, as in the first embodiment. Therefore, even in the configuration of the second embodiment, even when the kinetic energy of the ions changes due to contact with the CID gas when passing through the ion guide 40, the ions are prevented from being insufficiently bent or excessively bent. The ion guide 40 can be efficiently guided to the exit and emitted from the cell chamber 43.

[Third embodiment]
FIG. 7 is a schematic configuration diagram of a triple quadrupole mass spectrometer equipped with an ion guide according to the third embodiment. The same components as those in the above embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

In the third embodiment, four curved rod electrodes 411, 432, 413, instead of arranging a resistor so as to surround the curved rod electrode arranged inwardly in the configuration of the first embodiment, A plurality of curved rod electrodes 432 located inward of the curved portion 414 are divided in the longitudinal direction (in FIG. 7, for convenience, they are divided into seven, but the number of divisions is not limited to this). In addition to the high frequency voltage V _RF and the DC bias voltage V _BIAS , each of the electrode pieces from the voltage sources 6331 to 6337 is further divided into different direct currents for deflection. The voltage V _{DC1 to} V _DC7 is applied. The plurality of electrode pieces are arranged in series with a predetermined gap, thereby constituting one virtual curved rod electrode.
By appropriately setting the deflection DC voltages V _{DC1 to} V _DC7 to be applied to the electrode pieces from the voltage sources 6331 to 6337, the deflection DC voltage on the curved central axis O is set as in the first and second embodiments. A DC electric field whose field strength is greatest at the ion entrance side end and gradually decreases toward the exit side end can be formed to be superimposed on the high frequency electric field. Therefore, even in the configuration of the third embodiment, even when the kinetic energy of the ions changes due to contact with the CID gas when passing through the ion guide 40, the ions are prevented from being insufficiently bent or excessively bent. The ion guide 40 can be efficiently guided to the exit and emitted from the cell chamber 43.

  In the configurations of the second and third embodiments, as in the modification of the first embodiment, a converging DC electric field can be further formed to increase the ion converging efficiency.

[Fourth embodiment]
FIG. 8 is a schematic perspective view of an ion guide according to the fourth embodiment, and FIG. 9 is a plan view of a rod electrode of the ion guide according to the fourth embodiment. In addition, the same code | symbol is attached | subjected to the component same as the said Example, and detailed description is abbreviate | omitted.

  Each of the first to third embodiments is an ion guide in which the rod electrode itself has a curved shape. However, in the ion guide of the fourth embodiment, the rod electrode itself has a linear shape and is a space surrounded by the rod electrodes. The ion trajectory is curved in the space by the action of the electric field formed on the surface. That is, as shown in FIG. 8, in this ion guide 40, four rod electrodes 441, 442, 443, 444 are arranged substantially parallel to each other so as to surround the linear center axis Q. One of the rod electrodes 442 is provided with a cylindrical straight tubular resistor 44 so as to surround the rod electrode 442. Although this resistor 44 has a different shape, it has the same function as the resistor 42 in the first embodiment.

A voltage source (not shown) applies a voltage obtained by superimposing a predetermined DC bias voltage V _BIAS on the high-frequency voltage −V _RF to two opposing rod electrodes 441 and 443 of the four rod electrodes 441 to 444. In addition, the voltage source 641 generates a voltage obtained by superimposing a predetermined DC bias voltage V _BIAS on the high frequency voltage V _RF having the same amplitude and opposite polarity as the high frequency voltage −V _{RF on} the other two rod electrodes 442 and 444. Apply. The DC bias voltage V _BIAS is a voltage commonly applied to all the rod electrodes 441 to 444, and the DC bias voltage V _BIAS itself does not form a DC electric field inside the ion guide 40.

The voltage source 6431 deflects a first DC voltage −V _DCin having a polarity opposite to that of an ion to be analyzed (in this example, a positive ion) at an ion entrance side end of a resistor 44 surrounding one rod electrode 442. is applied as a DC voltage, voltage source 6432 is a voltage value in the first direct-current voltage -V _DCin the same polarity to the ion exit end of the resistive element antibodies 44 | smaller second DC voltage -V _DCout than | V _DCin Apply. As a result, a DC electric field that attracts ions toward the resistor 44 or the rod electrode 442 is formed inside the ion guide 40. Therefore, as shown in FIG. 9, ions that have entered the ion guide 40 substantially parallel to the central axis Q are separated from the central axis Q and approach the resistor 44 or the rod electrode 442 by the action of the DC electric field. Turn gradually to. In addition, since there is a voltage difference between the DC voltages applied to both ends of the resistor 44, the intensity of the DC electric field on the central axis Q is greatest at the end portion on the ion inlet side and toward the end portion on the outlet side. It becomes small gradually according to. In other words, the action of pulling ions introduced into the ion guide 40 in the direction of the resistor 44 or the rod electrode 442 is strongest at the inlet side end and gradually weakens toward the outlet side end. For this reason, even if the kinetic energy of the ions changes due to contact with the CID gas when passing through the ion guide 40, the ions are efficiently guided to the outlet of the ion guide 40 by avoiding insufficient ion bending or excessive bending. can do.

  As described above, any of the ion guides of the first to fourth embodiments according to the present invention responds to the energy change even when the kinetic energy of the ions changes in the internal space of the ion guide 40 due to the collision with the CID gas. Since the intensity of the direct current electric field for deflection is adjusted, it is possible to achieve high ion passage efficiency by avoiding insufficient bending or excessive bending of ions.

  In the above embodiment, the bending is performed by pulling the ions by the action of the DC electric field formed by the DC voltage applied to the resistor and the rod electrode. Conversely, the resistor and the rod positioned outside the curve. A DC electric field having an action of repelling (extruding) ions by a DC voltage applied to the electrode may be formed, and thereby the ion trajectory may be bent. Of course, in that case, unlike the above-described embodiment, it is natural that the intensity of the direct current electric field for deflection needs to be gradually increased from the inlet side end portion of the ion guide toward the outlet side end portion.

  In the above embodiment, the present invention is applied to the ion guide installed in the collision cell. However, not only in the collision cell but also as the ions progress due to collision with residual gas, etc. The present invention can be applied to all ion guides installed in a region where kinetic energy changes. For example, in a liquid chromatograph mass spectrometer or the like, a high-vacuum analysis chamber in which an ionization chamber that is an atmospheric pressure atmosphere in which atmospheric pressure ionization such as ESI or APCI is performed and a mass analyzer such as a quadrupole mass filter are installed. In between, a configuration of a multistage differential exhaust system in which a plurality of intermediate vacuum chambers are installed is adopted. In such a configuration, atmospheric gas continuously flows from the ionization chamber through the ion transport pipe into the intermediate vacuum chamber next to the ionization chamber, so that the residual gas concentration in the intermediate vacuum chamber is relatively high. Therefore, although the kinetic energy of ions is relatively high on the inlet side of the ion guide installed in the intermediate vacuum chamber, the ions collide with the residual gas as the ion guide proceeds and the kinetic energy decreases. It can be easily understood that the ion guide according to the present invention is effective for such an ion guide. Furthermore, the ion guide according to the present invention can be used not only in a mass spectrometer but also in various devices and apparatuses that handle ions.

  In addition, any of the above-described embodiments is merely an example, and it is obvious that even if appropriate modifications, corrections, and additions are made within the scope of the present invention, they are included in the scope of claims of the present application. For example, although the ion guide shown in the above embodiment is a quadrupole type or an octupole type, it may have a hexapole or a multipole configuration of ten or more.

DESCRIPTION OF SYMBOLS 1 ... Ionization part 2 ... Pre-stage quadrupole mass filter 3 ... Back-stage quadrupole mass filter 4 ... Collision cell 40 ... Ion guide 411-414, 422, 432 ... Curved rod electrodes 42, 44 ... Resistor 43 ... Cell chamber 441-444 ... Rod electrode 5 ... Detectors 611, 612, 613, 614, 623, 6331-6337, 6431, 6432 ... Voltage source O ... Curved central axis Q ... Central axis

Moreover, the 4th invention made in order to solve the said subject WHEREIN: In the ion guide which conveys an ion while making it converge,
a) 2n (n is an integer of 2 or more) rod electrodes arranged in parallel to each other so as to surround the linear central axis;
b) Voltage applying means for applying a voltage to each of the 2n rod electrodes, wherein the two high frequency electrodes are opposite in polarity to any two rod electrodes adjacent in the circumferential direction. High-frequency voltage applying means for applying a voltage;
c) Superposed on the high-frequency electric field formed in the space surrounded by the 2n rod electrodes, attracts ions in the space in one direction perpendicular to the central axis, and strengthens the electric field along the central axis. a deflecting electric field forming means for forming a polarization direction electric field you difference of,
It is characterized by having.

Claims (11)

In an ion guide that transports ions along a curved path while converging ions,
a) 2n (n is an integer of 2 or more) curved rod electrodes arranged so as to surround the curved central axis;
b) Voltage applying means for applying a voltage to each of the 2n curved rod electrodes, and any of the 2n curved rod electrodes adjacent to the circumferential direction centering on the curved central axis. High frequency voltage applying means for applying high frequency voltages having opposite polarities to the two curved rod electrodes;
c) Superimposes a high-frequency electric field formed in a space surrounded by the 2n curved rod electrodes, and causes ions in the space to be inside the curved central axis in a plane perpendicular to the curved central axis. A deflecting electric field forming means for generating a DC electric field attracting in a direction and having different electric field strengths along a curved central axis;
An ion guide comprising: The ion guide according to claim 1,
The deflection electric field forming means is arranged so as to extend along one curved rod electrode located inward or outward of the 2n curved rod electrodes. An ion guide comprising: a resistor; and DC voltage applying means for applying DC voltages having different potentials to an ion inlet side end and an outlet side end of the resistor, respectively. The ion guide according to claim 2,
The ion guide according to claim 1, wherein the resistor is a curved resistor disposed so as to surround one curved rod electrode positioned inwardly or outwardly. In an ion guide that transports ions along a curved path while converging ions,
a) 2n (n is an integer of 2 or more) curved rod electrodes arranged so as to surround the curved central axis, and one of them is located inside the curve or located outside The curved rod electrodes are arranged so that the distance from the curved central axis changes from the ion inlet side end toward the outlet side end; and
b) Voltage applying means for applying a voltage to each of the 2n curved rod electrodes, and any of the 2n curved rod electrodes adjacent to the circumferential direction centering on the curved central axis. High frequency voltage applying means for applying high frequency voltages having opposite polarities to the two curved rod electrodes;
c) Superimposes a high-frequency electric field formed in a space surrounded by the 2n curved rod electrodes, and causes ions in the space to be inside the curved central axis in a plane perpendicular to the curved central axis. The two curved rod electrodes are positioned inwardly or outwardly so as to form a DC electric field that is attracted in the direction and has different electric field strengths along the curved central axis. DC voltage application means for applying a DC voltage to one curved rod electrode;
An ion guide comprising: In an ion guide that transports ions along a curved path while converging ions,
a) 2n (n is an integer of 2 or more) curved rod electrodes arranged so as to surround the curved central axis, one of which is located inside the curve or located outside 2n curved rod electrodes which are virtual rod electrodes composed of a plurality of electrodes divided in the longitudinal direction;
b) Voltage applying means for applying a voltage to each of the 2n curved rod electrodes, and any of the 2n curved rod electrodes adjacent to the circumferential direction centering on the curved central axis. High frequency voltage applying means for applying high frequency voltages having opposite polarities to the two curved rod electrodes;
c) Superimposes a high-frequency electric field formed in a space surrounded by the 2n curved rod electrodes, and causes ions in the space to be inside the curved central axis in a plane perpendicular to the curved central axis. A plurality of electrodes constituting the virtual curved rod electrode from the ion inlet side end to the outlet side end so as to form a DC electric field attracting in the direction and having different electric field strengths along the curved central axis DC voltage application means for applying different DC voltages toward the part,
An ion guide comprising: An ion guide according to any one of claims 2 to 5,
A quadrupole configuration in which n is 2, the centers of the two curved rod electrodes facing each other across the curved central axis are located on the plane on which the curved central axis rests, and the other two Four curved rod electrodes are arranged so that the center of the curved rod electrode is positioned on a curved curved surface that is orthogonal to the plane and includes the curved central axis,
The DC voltage applying means applies a DC voltage to one of the two curved rod electrodes whose center is located on the plane or a resistor provided along the rod electrodes, An ion guide characterized in that a converging DC voltage having the same polarity as an ion to be analyzed is applied to two curved rod electrodes. In an ion guide that transports ions while converging them,
a) 2n (n is an integer of 2 or more) rod electrodes arranged in parallel to each other so as to surround the linear central axis;
b) Voltage applying means for applying a voltage to each of the 2n rod electrodes, wherein the two high frequency electrodes are opposite in polarity to any two rod electrodes adjacent in the circumferential direction. High-frequency voltage applying means for applying a voltage;
c) Superposed on the high-frequency electric field formed in the space surrounded by the 2n rod electrodes, attracts ions in the space in one direction perpendicular to the central axis, and strengthens the electric field along the central axis. A deflection electric field forming means for forming a deflection electric field for forming a DC electric field of different
An ion guide comprising: The ion guide according to claim 7,
The deflecting electric field forming means includes one resistor arranged so as to extend along a predetermined one of the 2n rod electrodes, and an entrance of ions in the resistor. An ion guide comprising: DC voltage applying means for applying DC voltages having different potentials to the side and the outlet side, respectively. The ion guide according to claim 8,
The ion guide according to claim 1, wherein the resistor is a resistor disposed so as to surround the predetermined one rod electrode or virtual rod electrode.   A mass spectrometer comprising a collision cell in which the ion guide according to claim 1 is disposed. A mass spectrometer having one or more intermediate vacuum chambers between an ionization chamber for ionizing a sample component under an atmospheric pressure atmosphere and an analysis chamber in which a mass analyzer is disposed,
A mass spectrometer, wherein the ion guide according to any one of claims 1 to 9 is disposed in an intermediate vacuum chamber next to the ionization chamber.

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