of these steps are especially difficult to perform, cumulatively they add a reasonable amount of time to the procedure, as well as the possibility of sample contamination.
A major advantage of CE is its instrumental simplicity. This allows a great deal of flexibility when designing a CE system for a particular application such as high throughput sampling and analysis. Blanco et al have shown the use of a sequential-injection CE device (SI-CE) for the analysis of inorganic anions associated with IEDs. Rather than using a vial to hold the sample, as with commercial CE instrumentation including the portable CE described above, Blanco et al introduced the sample via a flowing stream9
.
In this way rapid sample introduction was possible with a sampling rate of 60 samples/hour reported for the separation of 10 inorganic anions.
Although this shows that rapid analysis for IED related inorganic ions is possible, it didn’t look at the sampling process, that is, how the sample is best taken and introduced to the flow-through sampling interface. Subsequent work in
our laboratory has looked at extending the work of Blanco et al so as to be able to sample a given surface using a standard swabbing device and then directly inserting that swab into a specifically designed interface that automatically extracts and injects the contents of the swab to the previously described SI-CE system.
By
having this process fully automated it is hoped that sample turnaround should be less than 60 seconds meaning the instrument would be suitable for high throughput areas such as mass transit centres and public events. Direct mass spectrometry (MS) can also be used to analyse for inorganic IEDs.
Flanigan et al used laser vaporisation coupled to electrospray MS to directly analyse stainless steel sample plates that had been exposed to various explosive signatures including ammonium nitrate, chlorate, perchlorate, sugar and constituents contained within black powder10
. The advantages of the
described MS system was that it required no sample preparation (provided the materials to be analysed can be brought to the instrument), produced very quick
analysis times, and was capable of analysing for both anions, cations and neutral species simultaneously. Mass spectrometry as a detection method used in conjunction with a separation technique such as gas chromatography is not new but has made significant advances in terms of cost as well as ease of use in recent years11-14
especially for the analysis of
volatile species such as TATP. Spectrometry is also a useful technique for the detection of IEDs which relies on the interaction of the species to be determined with a light source, such as a laser.
performed in the direct mode, where a sample is directly introduced into the instrument, spectroscopic techniques also have the potential to be operated in an indirect standoff configuration where the instrument is housed some distance from the sampling site. This configuration is highly desirable since analyses can be performed in a less invasive and more user friendly manner. Additionally, samples can be analysed non-destructively and without disturbing a potentially sensitive sample.
While such analyses can be
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