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In this paper we describe the application of mass spectrometry (MS) to the detection of trace explosives.
We begin by reviewing the issue of explosives trace detection (ETD) and describe the method of
mass spectrometry (MS) as an alternative to existing technologies. Effective security screening devices
must be accurate (high detection and low false positive rate), fast and cost effective (upfront and operating
costs).
Ion mobility spectrometry (IMS) is the most commonly deployed method for ETD devices. Its advantages
are compact size and relatively low price. For applications requiring a handheld detector, IMS is
an excellent choice. For applications that are more stationary (e.g., checkpoint and alternatives to IMS are
available. MS is recognized for its superior performance with regard to sensitivity and specificity, which
translate to lower false negative and false positive rates. In almost all applications outside of security
where accurate chemical analysis is needed, MS is usually the method of choice and is often referred to as
the gold standard for chemical analysis.
There are many review articles and proceedings that describe detection technologies for explosives.
1,2,3,4 Here we compare MS and IMS and identify the strengths and weaknesses of each method.
- Mass spectrometry (MS): MS offers high levels of sensitivity and specificity compared to other
technologies for chemical detection. Its traditional disadvantages have been high cost and complexity.
Over the last few years, however, the economics have greatly improved and MS is now
capable of routine and automated operation.
Here we compare MS and IMS and identify the strengths and weaknesses of each method.
- Ion mobility spectrometry (IMS): 5
MS-ETD Screening System
IMS is similar in concept to MS except that the ions are dispersed
by gas-phase viscosity and not by molecular weight. The main advantage of IMS is that it
does not use a vacuum system, which greatly reduces the size, cost, and complexity relative to
MS. However, the trade-off is that the measurement accuracy is considerably less than MS. This
is especially true for complex samples or when screening for a large number of target compounds
simultaneously.
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