A voltage applied to an exit gate electrode forming a potential barrier and temporarily trapping ions within the inner space of the ion guide is higher than a voltage at an ion guide's exit end. A higher voltage is applied to the exit gate electrode for a lower m/z value of the measurement target ion, to push back the ion which has slowly moved along a potential gradient and reached the exit end of the ion guide. An ion having a lower m/z value is more likely to be located in a farther region from the exit end and forced to travel a longer distance when voltage applied to the exit gate electrode is lowered. A lower m/z value also means a higher travelling speed toward the orthogonal accelerator, whereby m/z dependency of the time required for travel from the ion guide to the orthogonal accelerator eventually becomes low.

An ion filter for a mass spectrometer, the apparatus comprising an ion modifier; an ion selector configured to select a subset of a sample of ions based on their mobility in a gas; and a controller configured to operate the ion modifier in a first mode to modify the ions selected by the ion selector to provide daughter ions, and configured to operate the ion modifier in a second mode to output the ions selected by the ion selector; wherein the ion filter is adapted for providing output ions from the ion modifier to an intake of a mass spectrometer.

The degree of ion dissociation which occurs within a first intermediate vacuum chamber (212) maintained at a comparatively low degree of vacuum depends not only on the amount of energy of the ion but also on the size and other properties of the ion. Accordingly, a predetermined optimum level of DC bias voltage is applied to an ion guide (24) so as to create, within the first intermediate vacuum chamber (212), a DC electric field which barely induces the dissociation of an ion originating from a target compound in a sample while promoting the dissociation of an ion originating from a foreign substance which will form a noise signal in the observation of the target compound. The optimum DC bias voltage is previously determined by creating extracted ion chromatograms based on data collected under various DC bias voltages and evaluating the SN ratio using the chromatograms. Consequently, the accuracy and sensitivity of the quantitative determination is improved as compared to a conventional system in which only the signal strength of the target compound is considered.

A linear ion trap includes at least two discrete trapping regions for processing ions, a RF electrical potential generator, a multi-output DC electrical potential generator, and a control unit. The RF electrical potential generator produces two RF waveforms each applied to a pair of pole electrodes of the linear ion trap forming a RF trapping field component to trap ions radially. The multi-output DC electrical potential generator produces multiple DC field components superimposed to the RF field component and distributed across the length of the linear ion trap to control ions axially. The control unit switches the DC electrical potentials and corresponding DC field components collectively forming a first trapping region populated with ions to alter ion potential energy from a first level to a second level, and enables a first ion processing step in at least one of the first and second levels.

A method of mass spectrometry is disclosed involving scanning a parameter of a first device through which a mixture of components is passed. Different components are transmitted through or produced in the first device at different values of the parameter and hence scanning the device parameter introduces a temporal modulation or profile to the components. This temporal variation is then removed prior to mass analysing the components through a process of homogenisation.

A mass spectrometer comprises: an ion source that generates ions having an initial range of mass-to-charge ratios; an auxiliary ion detector, downstream from the ion source that receives a plurality of first ion samples derived from the ions generated by the ion source and determines a respective ion current measurement for each of the plurality of first ion samples; a mass analyzer, downstream from the ion source that receives a second ion sample derived from the ions generated by the ion source and to generate mass spectral data by mass analysis of the second ion sample; and an output stage that establishes an abundance measurement associated with at least some of the ions generated by the ion source based on the ion current measurements determined by the auxiliary ion detector.

Systems and methods are provided for reducing the time period of a CID event of an MS.sup.3 experiment and making the overall fragmentation event more generic. A CID event of an MS.sup.3 experiment performed on a sample by a mass spectrometer is divided into two time periods using a processor. At the beginning of a first time period of the CID event, the mass spectrometer is instructed to both open a pulse valve in order to pulse a collision gas and apply a first CID voltage. At the beginning of a second time period of the CID event, the mass spectrometer is instructed to both close the pulse valve and apply a second CID voltage. The mass spectrometer is pumped down during the second time period. The overlap in time of the pump down and CID reduces the overall time period of the CID event.

A dwell time calculation table (51a) showing a correspondence relation between a CID gas pressure inside a collision cell (31) and a dwell time for data collection is stored in a processing condition parameter memory (51) of a controller (50). In the table (51a), as the CID gas pressure becomes higher, the dwell time becomes longer. When an instruction to execute an MRM measurement mode is given, the controller (50) determines the dwell time in accordance with the currently set CID gas pressure, and controls a data collector (41) to accumulate detection signals from an ion detector (34) during the determined dwell time and obtain the accumulated value. If the CID gas pressure inside the collision cell (31) is high, a decrease in ion speed becomes remarkable, and the rising of the ion intensity becomes slow. However, if the dwell time becomes long, influences of the slow rising on the accumulated value are relatively reduced, and the accuracy of the accumulated value is enhanced. Accordingly, the quantitative accuracy can be enhanced.

[Problem] To provide a mass spectrometry method that uses a chromatography-mass spectrometry device, wherein mass spectrometry can be performed with a convenient method at low cost. [Solution] A mass spectrometry method for a target object, using a chromatography-mass spectrometry device that includes, in order, a chromatograph, an ionization unit, a first mass separation unit, a collision cell, a second mass separation unit, and an ion detection unit, wherein an ion pair agent and Hünig's base are added to a mobile phase of the chromatograph, and the absolute value of an applied voltage of the collision cell is 20V to 250V.

An ion guide includes electrodes elongated along an axis from an entrance end to an exit end and spaced around the axis to surround an interior. The electrodes have polygonal shapes with inside surfaces disposed at a radius from the axis and having an electrode width tangential to a circle inscribed by the electrodes. An aspect ratio of the electrode width to the radius varies along the axis. The electrodes are configured to generate a two-dimensional RF electrical field in the interior having a multipole composition comprising one or more lower-order multipole components and one or more higher-order multipole components and varying along the axis in accordance with the varying aspect ratio, and having an RF voltage amplitude that varies along the axis.