A method of operating a quadrupole device (10) is disclosed. The quadrupole device (10) is operated in a mode of operation by applying a repeating voltage waveform comprising a main drive voltage and at least one auxiliary drive voltage is applied to the quadrupole device to the quadrupole device (10). The intensity of ions passing into the quadrupole device is varied with time in synchronisation with the repeating voltage waveform. This may be done such that the number of ions per unit phase which initially experience a phase within a first range of phases of the repeating voltage waveform is greater than the number of ions per unit phase which initially experience a phase within a second range of phases of the repeating voltage waveform.

A conversion circuit is arranged for converting an ion detection current (i.sub.D) produced by an ion detector into an ion detection signal (P). The conversion circuit comprises: an input stage for converting the ion detection current (i.sub.D) into an ion detection voltage (V.sub.D), an output stage for converting the ion detection voltage into the detection signal (P), the output stage being arranged for drawing a first current dependent on the ion detection voltage, and a supplementary stage for providing a second current (i.sub.S) dependent on the ion detection voltage to the output stage.

The second current may be substantially equal to the first current.

A quadrupole mass filter includes: four electrodes arranged to surround a central axis and constituting a quadrupole; attachment portions to which a plurality of electrical conductors are attached, at least one of the electrical conductors being arranged at a position that lies in a direction toward an area between each of the adjacent electrodes among the four electrodes, as viewed from the central axis; and a holder having a hollow portion and holding the four electrodes and the plurality of electrical conductors, wherein the electrical conductors are attached to the respective attachment portions and held by the holder with elasticity of a material constituting the electrical conductors.

An ion optical arrangement (1) for use in a mass spectrometer comprises electrodes (11, 12, 14) comprising a multipole arrangement defining an ion optical axis, and a voltage source for providing voltages to the electrodes to produce electric fields. The ion optical arrangement is configured for producing a radio frequency electric focusing field for focusing ions on the ion optical axis. The radio frequency electric focusing field has a varying frequency so as to reduce any mass dependence of ion trajectories through the ion optical arrangement. The ion optical arrangement may further be configured for producing a static electric field in response to a DC bias voltage applied to the multipole arrangement. A superimposed varying electric field may be produced by superimposing an AC voltage upon the DC bias voltage.

There is provided a gas analyzer apparatus that analyzes inflowing sample gas. The gas analyzer apparatus includes a filter unit that filters the sample gas, a detector unit that detects the result of filtering, a housing that houses these elements, and a control unit that controls the respective potentials of these elements. The control unit includes a cleaning control unit that sets the respective potentials of the filter unit, the detector unit, and the housing to cleaning potentials that draws in, as plasma for cleaning purposes, process plasma from a source that supplies the sample gas or plasma generated by a plasma generation unit.

A separation time of an isomer of one or more isomers of a sialylated glycopeptide of a sample is calculated from a peak of a precursor XIC. Product ion intensities of the first group are summed at the separation time producing a first sum and product ion intensities of the second group are summed at the separation time producing a second sum using XICs of the first and second groups. A ratio of the first sum to the second sum is calculated. The ratio at the separation time is compared to predetermined ratio ranges that each corresponds to a combination of a selection from a set of the first linkage and the second linkage taken one or more times. One or more linkages of the sialic acid to the glycan of the isomer are identified from a combination found to match the ratio in the comparison.

An analytical device for analysing ions is provided comprising a separator 2 for separating ions according to a physico-chemical property and an interface 3 comprising one or more ion guides. A quadrupole rod set mass filter 4 is arranged downstream of the interface 3. A control system is arranged and adapted: (i) to transmit a first group of ions which emerges from the separator 2 through the interface 3 with a first transit time t1 and (ii) to transmit a second group of ions which subsequently emerges from the separator 2 through the interface 3with a second different transit time t2.

An ion-optical device comprising: a plurality of electrodes (2); a first AC voltage supply (6); and a transformer (4) having: a toroidal core (8); a primary winding (10) connected to the AC voltage supply (6) and passing through the aperture within the toroidal core (8); and at least one secondary winding (13,15) wound around the toroidal core 8 and electrically connected to multiple ones of said plurality of electrodes.

In a mass spectrometer provided with a measurement section (1) including a collision cell (17) and a mass separator (20-23) for a mass spectrometric analysis of product ions, a CES-method-condition determiner (321) determines collision-energy (CE) values for a collision energy spread (CES) method according to given conditions including the range and number of CE values, in such a manner that n+1 CE values to be used when the number is n+1 (where n is an integer equal to or greater than three) include n collision-energy values used when the number is n and one additional CE value different from the n CE values. An analysis controller (30) sequentially changes the collision energy to the n+1 CE values and controls the measurement section to execute an MS/MS analysis under each CE value. A data processor (33) obtains a cumulative mass spectrum by accumulating mass spectra respectively obtained under different CE values.

Method and devices for performing top down analysis of an antibody are described which involve utilizing an ion source to generate a plurality of ions from a sample containing at least one intact antibody. Further, transmitting said plurality of ions through a quadrupole rod set while applying an RF signal thereto and in the absence of a resolving DC voltage so as to preferentially transmit precursor ions having an m/z value greater than a low mass cutoff of about 1500 m/z from the quadrupole rod set to an ECD cell. The method and device can also performing an ECD reaction in the ECD cell on said precursor ions and also detect reaction products from the ECD reaction.