Ion analysis apparatus and method of use

An ion analysis apparatus comprising:

• an ionization source for generating ions from a sample;
• and
• an ion detector;
• wherein in use ions travel along an ion optical axis from the ionization source to the ion detector, the apparatus further comprising:
• a vacuum enclosure including
• a first vacuum region containing differential ion mobility means;
• and
• a second vacuum region containing a mass analyzer;
• pumping means configured to provide a pressure in the second vacuum region that is lower than the pressure in the first vacuum region;
• an ion inlet connecting the ionization source to the first vacuum region,
• wherein the first vacuum region is located before the second vacuum region on the ion optical axis such that in use ions generated from the sample undergo differential ion mobility analysis before mass analysis;
• and wherein in use the first vacuum region including the differential ion mobility means is at a pressure in the range 2 kPa to 40 kPa and the differential ion mobility means is driven by an asymmetric waveform having a frequency in the range 20 kHz to 25 MHz;
• and wherein an apparatus includes gas flow means for establishing a flow of gas into the first vacuum region so as to provide a gas medium for the differential ion mobility means.

A method of analyzing ions, which method comprises the steps of:

• (a) generating ions from a sample in an ionization source;
• (b) delivering the ions through an ion inlet into a first vacuum region of a vacuum enclosure;
• (c) in the first vacuum region, prior to mass analysis of the ions, conducting differential ion mobility analysis of the ions;
• (d) after differential ion mobility analysis, delivering the ions to a second vacuum region of the vacuum enclosure;
• and
• (e) in the second vacuum region conducting mass analysis of the ions;
• and wherein in use the first vacuum region including the differential ion mobility means is at a pressure in the range 2 kPa to 40 kPa and the differential ion mobility means is driven by an asymmetric waveform having a frequency in the range 20 kHz to 25 MHz;
• and wherein the method includes establishing a flow of gas into the first vacuum region so as to provide a gas medium for the said differential ion mobility analysis.

An ion analysis apparatus comprising:

• an ionization source for generating ions from a sample;
• and
• an ion detector;
• wherein in use ions travel along an ion optical axis from the ionization source to the ion detector, the apparatus further comprising:
• a vacuum enclosure including
• a first vacuum region containing differential ion mobility means;
• and
• a second vacuum region containing a mass analyzer;
• pumping means configured to provide a pressure in the second vacuum region that is lower than the pressure in the first vacuum region;
• an ion inlet connecting the ionization source to the first vacuum region,
• the first vacuum region being located before the second vacuum region on the ion optical axis such that in use ions generated from the sample undergo differential ion mobility analysis before mass analysis,
• wherein the differential ion mobility means comprises a multipole wherein a plurality of elongate electrodes are arranged circumferentially around a common axis, with the longitudinal axes of the electrodes being parallel,
• and wherein the apparatus includes a waveform generator configured to provide (i) a dipole field and (ii) a higher order field within the multipole.

A method of analyzing ions, which method comprises the steps of:

• (a) generating ions from a sample in an ionization source;
• (b) delivering the ions through an ion inlet into a first vacuum region of a vacuum enclosure;
• (c) in the first vacuum region, prior to mass analysis of the ions, conducting differential ion mobility analysis of the ions;
• (d) after differential ion mobility analysis, delivering the ions to a second vacuum enclosure;
• and
• (e) in the second vacuum region conducting mass analysis of the ions;
• wherein step (c) includes conducting differential ion mobility analysis with a multipole comprising a plurality of elongate electrodes arranged circumferentially around a common axis, with the longitudinal axes of the electrodes being parallel,
• and wherein step (c) includes applying (i) a dipole field and (ii) a higher order field within the multipole.