Multidimensional Ion Mobility Spectrometry Apparatus and Methods

A method for operating a ion mobility spectrometric system comprising:

• a. ionizing chemical species;
• b. conveying the ionized chemical species down a first drift axis of a first drift tube;
• c. conveying the ionized chemical species down a second drift axis of a second drift tube that is coupled to the first drift tube;
• and
• d. detecting ions in the second drift tube.

A method for operating an ion mobility spectrometer, the method comprising:

• a. pulsing a gas phase sample into a first drift tube at a first time;
• b. conveying the gas phase sample pulse in a first direction along at least a portion of the first drift tube;
• c. providing a plurality of pulses of reactant ions into the first drift tube at predetermined times relative to the first time;
• d. generating an electric field that conveys the pulses of reactant ions in a second direction along at least a portion of the first drift tube, wherein the second direction is substantially anti-parallel to the direction of a carrier gas flow in the first drift tube;
• and
• e. interacting a group of reactant ions, comprising one or more of the plurality of pulses of reactant ions, with the gas phase sample pulse to ionize a chemical species in the gas phase sample pulse.

A method for ion mobility spectrometry, the method comprising:

• a. introducing a sample into a first drift tube;
• b. ionizing at least some of the sample to form ionic chemical species;
• c. separating at least some of the ionic chemical species along the first drift axis by interacting the ionic chemical species with a first drift gas under a first set of drift conditions;
• d. generating an electric field proximate to a second drift tube to extract the ionic chemical species into the second drift tube;
• e. separating at least some the ionic chemical species along a second drift axis by interacting the ionic chemical species with a second drift gas under a second set of drift conditions;
• and
• f. detecting at least some of the separated ionic chemical species with an ion detector.

An ion mobility spectrometer system comprising:

• a. a first drift tube having a first drift axis;
• b. a second drift tube having a second drift axis substantially perpendicular to the first drift axis and an inlet that is coupled to the first drift tube;
• c. a third drift tube having a third drift axis substantially parallel to the second drift axis and substantially perpendicular to the first drift axis, and having an inlet that is coupled with the first drift tube;
• d. an electrode positioned proximate to the inlet of the second drift tube;
• and
• e. an electrode positioned proximate to the inlet of the third drift tube.

A method for operating an ion mobility spectrometer, the method comprising:

• a. providing a gas sample comprising positive ion chemical species and negative ion chemical species to a first drift tube;
• b. conveying the ionic chemical species into a drift region of the first drift tube with a carrier gas flow;
• c. applying an electric field proximate to an inlet of a second and a third drift tube to extract at least a portion of the positive ion chemical species into a second drift tube and to extract at least a portion of the negative ion chemical species into the third drift tube;
• d. spatially separating along the second drift axis one or more of the positive ion chemical species by collisions with a second carrier gas in the second drift tube and detecting at least a portion of the separated positive ion chemical species with an ion detector;
• and
• e. spatially separating along the third drift axis one or more of the negative ion chemical species by collisions with a third carrier gas in the third drift tube and detecting at least a portion of the separated negative ion chemical species with an ion detector.