Abstract: In a first-stage intermediate vacuum chamber, cluster ions causing a background noise are dominantly formed in area (A), while fragment ions are dominantly generated in area (B). Taking this fact into account, in an in-source CID analysis mode, a DC voltage higher than that applied to a skimmer is applied to a first ion guide so as to create an accelerating electric field in area (B), whereby the ions are sufficiently energized to promote the fragmentation. When the in-source CID is not performed, a DC voltage higher than that applied to the first ion guide is applied to the exit end of a desolvation tube so as to create an accelerating electric field only in area (A) without creating such a field in area (B), whereby both the formation of the cluster ions and the generation of the fragment ions are suppressed, so that a high-quality chromatogram can be obtained.

Abstract: During a halt period of time when the introduction of ions is temporarily discontinued to change an objective ion to be selected by a first mass separator in the previous stage, a pulsed voltage having a polarity opposite to that of the ions remaining in a collision cell (4) is applied to an entrance lens electrode (42) and exit lens electrode (44). The ions are pulled by the DC electric field created by this voltage, to be neutralized and removed by colliding with the lens electrodes (42, 44). Thus, the residual ions, which may cause a crosstalk, can be quickly removed from the inner space of the collision cell (4) without contaminating an ion guide (5) to which a radio-frequency is applied. Since no radio-frequency voltage is applied to the lens electrodes (42, 44), the circuit for applying the pulsed voltage can have a simple configuration. Thus, the cost increase is suppressed.

Abstract: A mass analysis of a standard sample having a known mass-to-charge ratio is carried out by performing a mass scan at a first-stage quadrupole (13) over a predetermined mass range, under the condition that a collision induced dissociation (CID) gas is introduced into a collision cell (14) and a voltage applied to a third-stage quadrupole (17) is set so that no substantial mass separation occurs in this quadrupole. Various kinds of product ions originating from a precursor ion selected by the first-stage quadrupole (13) arrive at and are detected by a detector (18) without being mass separated. Accordingly, based on the detection data, a data processor (25) can obtain a relationship between the voltage applied to the first-stage quadrupole (13) and the mass-to-charge ratio of the selected ions, with a time delay in the collision cell (14) reflected in that relationship. This relationship is stored in a calibration data memory (26), to be utilized in a neutral loss scan measurement or the like.

Abstract: The gas conductance on the ion injection side of a collision cell is made larger than the gas conductance on the ion exit side by providing two ion injection apertures 23, 25 in the collision cell. Due to the different gas conductances, a CID gas supplied through the gas supply tube 31 generally flows in a direction from the ion injection side to the ion exit side in the collision cell, namely, in the ion's passage direction. When the ions injected in the collision cell 20 slow down upon contacting with the CID gas, their progress is assisted by the gas flow, so that the delay of the ions in the collision cell 20 is alleviated. As a result, it is possible to avoid a deterioration in the detection sensitivity of a target product ion and to prevent a ghost peak caused by the stay of the ions.

Abstract: The gas conductance on the ion injection side of a collision cell is made larger than the gas conductance on the ion exit side by providing two ion injection apertures 23, 25 in the collision cell. Due to the different gas conductances, a CID gas supplied through the gas supply tube 31 generally flows in a direction from the ion injection side to the ion exit side in the collision cell, namely, in the ion's passage direction. When the ions injected in the collision cell 20 slow down upon contacting with the CID gas, their progress is assisted by the gas flow, so that the delay of the ions in the collision cell 20 is alleviated. As a result, it is possible to avoid a deterioration in the detection sensitivity of a target product ion and to prevent a ghost peak caused by the stay of the ions.

Abstract: An electrode member (11, 12) having two electrode plain plate portions (21) and one circular portion (20) is created from a single metal plate, where the two electrode plain plate portions (21) belong to every other virtual rod electrode around the ion optical axis and face across the ion optical axis, and the circular portion (20) electrically connects these two electrode plain plate portions (21). A predetermined number of resin electric holders (13) each holding the electrode member (11, 12) are stacked in the ion optical axis direction, with every other electric member rotated by 90° around the ion optical axis, to form a virtual quadrupole rod type ion guide. Since this configuration reduces the number of components more than ever before and saves a cable for connecting electrode plain plate portions (21, 25) to which the same voltage should be applied, it is possible to reduce the cost and facilitate assembly and regulation in manufacturing and use.

Abstract: The direct current bias voltage to be applied to the pre-filter provided in the previous stage of the quadrupole mass filter for selecting an ion according to the mass-to-charge ratio is changed in accordance with the mass-to-charge ratio of the target ion to be allowed to pass through, in order that the time period required for an ion to pass through the pre-filter is uniformed regardless of the mass-to-charge ratio, and simultaneously the phase of the oscillation of ions at the entrance of the quadrupole mass filter is also uniformed. In the range where the mass-to-charge ratio is larger than some degree, the ion's oscillation itself is small, and in addition, the ion's passage efficiency deteriorates rather than enhances, due to the potential barrier created by the voltage difference from the direct current bias voltage applied to the quadrupole mass filter.

Abstract: The length of the collision cell (20) in the direction along the ion optical axis (C) is set to be within the range between 40 and 80 mm, and typically 51 mm, which is remarkably shorter than before. The CID gas is supplied so that it flows in the direction opposite to the ion's traveling direction. Since the energy that an ion receives in colliding with a CID gas increases, it is possible to practically and sufficiently ensure the CID efficiency even though the collision cell (20) is short. In addition, since the passage distance for an ion is short, the passage time is shortened. Accordingly, it is possible to avoid the degradation in the detection sensitivity and the generation of a ghost peak due to the delay of the ion.

Abstract: One virtual rod electrode is composed by a plurality of electrode plane plates arranged in the ion optical axis direction, and four virtual rod electrodes are arranged around the ion optical axis to form a virtual quadrupole rod type ion transport optical system (30). In one virtual rod electrode, the interval between the adjacent electrode plane plates is set to be large in the anterior area (30A) and small in the posterior area (30B). As the interval between electrodes becomes larger, high-order multipole field components increase and therefore the ion acceptance is increased, which enables an efficient acceptance of ions coming from the previous stage. On the other hand, if the interval between electrodes is small, the quadrupole field components relatively increase and the ion beam's convergence is improved. Therefore, ions can be effectively introduced into a quadrupole mass filter for example in the subsequent stage, which contributes to the enhancement of the mass analysis' sensitivity and accuracy.

Abstract: A mass analysis of a standard sample having a known mass-to-charge ratio is carried out by performing a mass scan at a first-stage quadrupole (13) over a predetermined mass range, under the condition that a collision induced dissociation (CID) gas is introduced into a collision cell (14) and a voltage applied to a third-stage quadrupole (17) is set so that no substantial mass separation occurs in this quadrupole. Various kinds of product ions originating from a precursor ion selected by the first-stage quadrupole (13) arrive at and are detected by a detector (18) without being mass separated. Accordingly, based on the detection data, a data processor (25) can obtain a relationship between the voltage applied to the first-stage quadrupole (13) and the mass-to-charge ratio of the selected ions, with a time delay in the collision cell (14) reflected in that relationship. This relationship is stored in a calibration data memory (26), to be utilized in a neutral loss scan measurement or the like.

Abstract: A radio-frequency ion guide (20) for converging ions by a radio-frequency electric field and simultaneously transporting the ions into the subsequent stage is composed of eight rod electrodes (21 through 28) arranged in such a manner as to surround an ion optical axis (C). Each of the rod electrodes (21 through 28) is disposed at a tilt with respect to the ion optical axis (C) so that the radius r2 of the inscribed circle (29b) at the end face of the ion exit side is larger than the radius r1 of the inscribed circle (29a) at the end face of the ion injection side. Accordingly, the gradient of the magnitude or depth of the pseudopotential is formed in the ion's traveling direction in the space surrounded by the rod electrodes (21 through 28). Ions are accelerated in accordance with this gradient. Therefore, even in the case where the gas pressure is relatively high and ions have many chances to collide with gas, it is possible to moderate the ions' slowdown and prevent the ions' delay and stop.

Abstract: A radio-frequency ion guide (20) for converging ions by a radio-frequency electric field and simultaneously transporting the ions into the subsequent stage is composed of eight rod electrodes (21 through 28) arranged in such a manner as to surround an ion optical axis (C). Each of the rod electrodes (21 through 28) is disposed at a tilt with respect to the ion optical axis (C) so that the radius r2 of the inscribed circle (29b) at the end face of the ion exit side is larger than the radius r1 of the inscribed circle (29a) at the end face of the ion injection side. Accordingly, the gradient of the magnitude or depth of the pseudopotential is formed in the ion's traveling direction in the space surrounded by the rod electrodes (21 through 28). Ions are accelerated in accordance with this gradient. Therefore, even in the case where the gas pressure is relatively high and ions have many chances to collide with gas, it is possible to moderate the ions' slowdown and prevent the ions' delay and stop.

Abstract: During a halt period of time when the introduction of ions is temporarily discontinued to change an objective ion to be selected by a first mass separator in the previous stage, a pulsed voltage having a polarity opposite to that of the ions remaining in a collision cell (4) is applied to an entrance lens electrode (42) and exit lens electrode (44). The ions are pulled by the DC electric field created by this voltage, to be neutralized and removed by colliding with the lens electrodes (42, 44). Thus, the residual ions, which may cause a crosstalk, can be quickly removed from the inner space of the collision cell (4) without contaminating an ion guide (5) to which a radio-frequency is applied. Since no radio-frequency voltage is applied to the lens electrodes (42, 44), the circuit for applying the pulsed voltage can have a simple configuration. Thus, the cost increase is suppressed.

Abstract: The gas conductance on the ion injection side of a collision cell is made larger than the gas conductance on the ion exit side by providing two ion injection apertures 23, 25 in the collision cell. Due to the different gas conductances, a CID gas supplied through the gas supply tube 31 generally flows in a direction from the ion injection side to the ion exit side in the collision cell, namely, in the ion's passage direction. When the ions injected in the collision cell 20 slow down upon contacting with the CID gas, their progress is assisted by the gas flow, so that the delay of the ions in the collision cell 20 is alleviated. As a result, it is possible to avoid a deterioration in the detection sensitivity of a target product ion and to prevent a ghost peak caused by the stay of the ions.

Abstract: A radio-frequency ion guide (20) for converging ions by a radio-frequency electric field and simultaneously transporting the ions into the subsequent stage is composed of eight rod electrodes (21 through 28) arranged in such a manner as to surround an ion optical axis (C). Each of the rod electrodes (21 through 28) is disposed at a tilt with respect to the ion optical axis (C) so that the radius r2 of the inscribed circle (29b) at the end face of the ion exit side is larger than the radius r1 of the inscribed circle (29a) at the end face of the ion injection side. Accordingly, the gradient of the magnitude or depth of the pseudopotential is formed in the ion's traveling direction in the space surrounded by the rod electrodes (21 through 28). Ions are accelerated in accordance with this gradient. Therefore, even in the case where the gas pressure is relatively high and ions have many chances to collide with gas, it is possible to moderate the ions' slowdown and prevent the ions' delay and stop.

Abstract: One virtual rod electrode is composed by a plurality of electrode plain plates arranged in the ion optical axis direction, and four virtual rod electrodes are arranged around the ion optical axis to form a virtual quadrupole rod type ion transport optical system (30). In one virtual rod electrode, the interval between the adjacent electrode plain plates is set to be large in the anterior area (30A) and small in the posterior area (30B). As the interval between electrodes becomes larger, high-order multipole field components increase and therefore the ion acceptance is increased, which enables an efficient acceptance of ions coming from the previous stage. On the other hand, if the interval between electrodes is small, the quadrupole field components relatively increase and the ion beam's convergence is improved. Therefore, ions can be effectively introduced into a quadrupole mass filter for example in the subsequent stage, which contributes to the enhancement of the mass analysis' sensitivity and accuracy.

Abstract: The length of the collision cell (20) in the direction along the ion optical axis (C) is set to be within the range between 40 and 80 mm, and typically 51 mm, which is remarkably shorter than before. The CID gas is supplied so that it flows in the direction opposite to the ion's traveling direction. Since the energy that an ion receives in colliding with a CID gas increases, it is possible to practically and sufficiently ensure the CID efficiency even though the collision cell (20) is short. In addition, since the passage distance for an ion is short, the passage time is shortened. Accordingly, it is possible to avoid the degradation in the detection sensitivity and the generation of a ghost peak due to the delay of the ion.

Abstract: An electrode member (11, 12) having two electrode plain plate portions (21) and one circular portion (20) is created from a single metal plate, where the two electrode plain plate portions (21) belong to every other virtual rod electrode around the ion optical axis and face across the ion optical axis, and the circular portion (20) electrically connects these two electrode plain plate portions (21). A predetermined number of resin electric holders (13) each holding the electrode member (11, 12) are stacked in the ion optical axis direction, with every other electric member rotated by 90° around the ion optical axis, to form a virtual quadrupole rod type ion guide. Since this configuration reduces the number of components more than ever before and saves a cable for connecting electrode plain plate portions (21, 25) to which the same voltage should be applied, it is possible to reduce the cost and facilitate assembly and regulation in manufacturing and use.

Abstract: The inside of the collision cell 20 placed in the analysis chamber 10 which is vacuum-evacuated is partitioned into an anterior chamber 23 and a posterior chamber 24 by the partition wall 21 with a communicating aperture 22. The former is used as a dissociation area A1 and the latter as a convergence area A2. Electrodes 27 and 28 for forming a radio-frequency electric field are placed in the chambers 23 and 24, respectively. When a CID gas is supplied into the anterior chamber 23, the CID gas is dispersed inside the anterior chamber 23 and flows into the analysis chamber 10 via the posterior chamber 24. Consequently, the gas pressure in the posterior chamber becomes higher than the gas pressure in the analysis chamber 10, and the gas pressure in the anterior chamber 23 becomes higher than the gas pressure in the posterior chamber 24.

Abstract: The direct current bias voltage to be applied to the pre-filter 13 provided in the previous stage of the quadrupole mass filter 14 for selecting an ion according to the mass-to-charge ratio is changed in accordance with the mass-to-charge ratio of the target ion to be allowed to pass through, in order that the time period required for an ion to pass through the pre-filter 13 is uniformed regardless of the mass-to-charge ratio, and simultaneously the phase of the oscillation of ions at the entrance of the quadrupole mass filter 14 is also uniformed. In the range where the mass-to-charge ratio is larger than some degree, the ion's oscillation itself is small, and in addition, the ion's passage efficiency deteriorates rather than enhances, due to the potential barrier created by the voltage difference from the direct current bias voltage applied to the quadrupole mass filter 14.