A DMS device receives a curtain gas that includes a chemical modifier into its curtain plate. Before or while receiving ions of an analyte, the DMS device steps the CoV through a series of values in order to apply different CoV values to at least one precursor ion derived from the chemical modifier. For each CoV value of the series of values, a mass spectrometer selects and mass analyzes the at least one precursor ion. An intensity is produced for each CoV value of the series of values. An intensity versus CoV value peak is calculated from the intensities measured. A representative CoV value is calculated for the peak. The difference between the representative CoV value and known CoV values that represent an uncontaminated curtain plate is calculated. If the difference is greater than or equal to a predetermined threshold value, the curtain plate is determined to be contaminated.

A DMS device receives a curtain gas that includes a chemical modifier into its curtain plate. Before or while receiving ions of an analyte, the DMS device steps the CoV through a series of values in order to apply different CoV values to at least one precursor ion derived from the chemical modifier. For each CoV value of the series of values, a mass spectrometer selects and mass analyzes the at least one precursor ion. An intensity is produced for each CoV value of the series of values. An intensity versus CoV value peak is calculated from the intensities measured. A representative CoV value is calculated for the peak. The difference between the representative CoV value and known CoV values that represent an uncontaminated curtain plate is calculated. If the difference is greater than or equal to a predetermined threshold value, the curtain plate is determined to be contaminated.

The waveform generator (10) comprises a switch (13). The waveform generator (10) comprises a transformer (15) having a primary side circuit and a secondary side circuit. The primary side circuit has a first terminal arranged to be conductively coupled to a DC voltage source, and a second terminal conductively coupled to the switch (13). The waveform generator (10) further comprises a controller (11) arranged to supply a drive signal to the switch for switching the switch between on and off states. The controller (11) is arranged to adjust the frequency of the drive signal so as to control at least one of the peak voltage and the duty cycle of a waveform generated by the waveform generator (10). The frequency of the drive signal may be adjusted as the voltage level of the DC voltage source remains constant. The frequency of the drive signal may be adjusted in response to a change in the voltage level of the DC voltage source.

An arrangement for providing a waveform for driving an ion mobility device. The arrangement comprises at least a plurality of switching circuits, each switching circuit comprising at least two switches operatively coupled to a first voltage source (VH), wherein the plurality of switching circuits is arranged to be coupled in parallel with respect to each other. The arrangement additionally comprises an interleaving circuit configured to receive a time-varying electrical input signal exhibiting an input frequency and based on said input signal, operate the plurality of switching circuits to provide a waveform via the switches, said waveform exhibiting a switching frequency that is essentially equivalent to the input frequency.

An arrangement for providing a waveform for driving an ion mobility device. The arrangement comprises at least a plurality of switching circuits, each switching circuit comprising at least two switches operatively coupled to a first voltage source (VH), wherein the plurality of switching circuits is arranged to be coupled in parallel with respect to each other. The arrangement additionally comprises an interleaving circuit configured to receive a time-varying electrical input signal exhibiting an input frequency and based on said input signal, operate the plurality of switching circuits to provide a waveform via the switches, said waveform exhibiting a switching frequency that is essentially equivalent to the input frequency.

A method of analysis using mass spectrometry and/or ion mobility spectrometry is disclosed. The method comprises: using a first device to generate smoke, aerosol or vapour from a target comprising or consisting of a microbial population; mass analysing and/or ion mobility analysing said smoke, aerosol or vapour, or ions derived therefrom, in order to obtain spectrometric data; and analysing said spectrometric data in order to analyse said microbial population.

A method of analysis using mass spectrometry and/or ion mobility spectrometry is disclosed. The method comprises: using a first device to generate smoke, aerosol or vapour from a target comprising or consisting of a microbial population; mass analysing and/or ion mobility analysing said smoke, aerosol or vapour, or ions derived therefrom, in order to obtain spectrometric data; and analysing said spectrometric data in order to analyse said microbial population.

A detection cell includes a pair of filter electrodes, disposed separated from and opposing each other. One of the pair of filter electrodes includes a first region provided following a flow direction of an object of measurement introduced between the filter electrodes, and a second region that is provided arrayed with the first region regrading an intersecting direction intersecting the flow direction, and that protrudes to a position at which a distance of separation as to another of the pair of filter electrodes is smaller than that of the first region. First and second downstream-side electrodes are respectively disposed on downstream sides of the first and second regions, in the flow direction, and are separated from each other regarding the intersecting direction. First and second opposing electrodes are disposed on the downstream side from the other of the pair of filter electrodes, and oppose the first and second downstream-side electrodes.

A detection cell includes a pair of filter electrodes, disposed separated from and opposing each other. One of the pair of filter electrodes includes a first region provided following a flow direction of an object of measurement introduced between the filter electrodes, and a second region that is provided arrayed with the first region regrading an intersecting direction intersecting the flow direction, and that protrudes to a position at which a distance of separation as to another of the pair of filter electrodes is smaller than that of the first region. First and second downstream-side electrodes are respectively disposed on downstream sides of the first and second regions, in the flow direction, and are separated from each other regarding the intersecting direction. First and second opposing electrodes are disposed on the downstream side from the other of the pair of filter electrodes, and oppose the first and second downstream-side electrodes.

A system and method comprising an ion production chamber having an ultra-violet light source disposed towards said chamber, a coated quartz plate between the chamber and the UV source whose coating absorbs incident UV light and ejects electrons into the chamber through the photoelectric effect, a harvest gas disposed to flow through the chamber from an inlet to an outlet, and a jet operable to introduce a sample into the harvest gas flow. In some embodiments the system includes using helium as the harvest gas. Certain embodiments include introducing a sample perpendicular to the harvest gas flow and using multiple sample introduction jets to increase mixing efficiency. In some embodiments the harvest gas and particle sample jet are one and the same. The charge sample may be coupled to a MEMS-based electrometer.