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Ion Mobility Spectrometry

Field-portable Instrumentation

  1. Lourdes Arce

Published Online: 15 DEC 2010

DOI: 10.1002/9780470027318.a9169

Encyclopedia of Analytical Chemistry

Encyclopedia of Analytical Chemistry

How to Cite

Arce, L. 2010. Ion Mobility Spectrometry. Encyclopedia of Analytical Chemistry. .

Author Information

  1. University of Córdoba, Department of Analytical Chemistry, Córdoba, Spain

Publication History

  1. Published Online: 15 DEC 2010

Abstract

Ion mobility spectrometry (IMS) is known to be a fast technique for the detection of volatile compounds. In IMS, a gas-phase sample is ionized using an ionization source. The ions move in a weak electrical field toward a detector. During the drift they collide with a drift gas flowing in the opposite direction. Therefore, they are slowed down depending on their size, shape, and charge. As a result, different ions reach the detector at different drift times, which is a characteristic of the ions considered. The number of ions reaching the detector is a measure of the concentration of the analyte. Ions with greater mobility reach the collector electrode earlier than heavier ions that have a lower mobility. The current induced in the ion collector is an output signal from IMS detector. Its time dependence is called drift time spectrum. With regard to electric field direction, it is possible to measure spectra of positive or negative ions.

IMS can be manufactured in small, rugged, and portable designs and it has been used in several critical mission circumstances from security screening and military preparedness. Perhaps the most visible are the IMS analyzers that have been deployed in airports around the world to detect traces of explosives in passengers' carry-on luggage.

Keywords:

  • ion mobility spectrometry;
  • gas-phase separation;
  • gas-phase electrophoretic;
  • sensor;
  • volatile compounds