Ion Mobility Spectrometry in Forensic Science

Abstract

Ion mobility spectrometry (IMS) is an analytical technique that has primarily been used as a trace chemical monitor in the field. The benefits of IMS as a field detector are its simplicity, sensitivity, fast analysis times, portability, ruggedness, and its operation at ambient pressures. IMS has successfully been used for many years to detect traces of explosives at airports and other security checkpoints; illicit drugs in prisons, cargo, and in border security. The military have long used IMS for detection of chemical warfare agents. Innovations in drift tubes, nonradioactive ion sources, and hyphenated IMS techniques in recent years have expanded the range of forensic applications. A sample introduced into the IMS undergoes atmospheric pressure chemical ionization and the resulting product ions are separated by their mobilities in the drift tube. Several factors such as temperature, humidity, concentration and presence of interferences can affect the ionization and separation process. This article describes the principles of IMS, developments in technology, and their implications for forensic science. IMS trends in detection of explosives, illicit drugs, and chemical warfare agents are discussed. The article also provides an overview of some unconventional applications and some interesting emerging forensic applications of IMS.

Large‐scale evaluation of ion mobility spectrometry for the rapid detection of synthetic cannabinoid receptor agonists in infused papers in prisons

“…Ion mobility spectrometers (IMS) and other rapid detection devices are established tools for the screening and preliminary identification of unknown substances in a security context, 26–29 particularly for the detection of trace levels of explosives and drugs within airports 30 . Analytes are introduced into the instrument on a sampling device (referred to as a sample trap) and are volatilized in a heated ionization chamber.…”

“…25 Those supplying SCRAs have attempted to circumvent this security measure by disguising the infused letters as legally privileged mail, often referred to as "Rule 39" mail in England and Wales 24 or simply as "Legal Mail" in Scotland, 25 which cannot be opened or read by prison staff. 24,25 Ion mobility spectrometers (IMS) and other rapid detection devices are established tools for the screening and preliminary identification of unknown substances in a security context, [26][27][28][29] particularly for the detection of trace levels of explosives and drugs within airports. 30 Analytes are introduced into the instrument on a sampling device (referred to as a sample trap) and are volatilized in a heated ionization chamber.…”

Deploying Portable Gas Chromatography–Mass Spectrometry (GC-MS) to Military Users for the Identification of Toxic Chemical Agents in Theater

“…[30][31][32] Other methods such as ion mobility spectrometry (IMS) can detect and presumptively identify trace residues of chemicals (in some instances down to a few nanograms or less), 33 but not when these trace residues are in complex sample matrices. 34,35 Portable GC-MS systems, on the other hand, can reliably and rapidly detect and identify these substances at low concentrations, even when the substance is masked in a complex matrix.…”

Differentiation of Body Fluid Stains Using a Portable, Low-Cost Ion Mobility Spectrometry Device—A Pilot Study

“…IMS is a technique currently employed for other forensic and security applications and has historically been used for the detection of volatile compounds spanning several forensic applications, including the identification of explosives [ 22 , 23 ], drugs [ 22 , 23 ] and chemical weapons [ 23 ]. Static scanning devices are commonly employed at airports and borders [ 24 ] to aid in the detection of threats (explosives) and contraband (drugs).…”