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Ely, United Kingdom

Barber S.,University of Leicester | Blake R.S.,University of Leicester | White I.R.,University of Leicester | Monks P.S.,University of Leicester | And 3 more authors.
Analytical Chemistry | Year: 2012

A drift tube capable of simultaneously functioning as an ion funnel is demonstrated in proton transfer reaction mass spectrometry (PTR-MS) for the first time. The ion funnel enables a much higher proportion of ions to exit the drift tube and enter the mass spectrometer than would otherwise be the case. An increase in the detection sensitivity for volatile organic compounds of between 1 and 2 orders of magnitude is delivered, as demonstrated using several compounds. Other aspects of analytical performance explored in this study include the effective E/N (ratio of electric field to number density of the gas) and dynamic range over which the drift tube is operated. The dual-purpose drift tube/ion funnel can be coupled to various types of mass spectrometers to increase the detection sensitivity and may therefore offer considerable benefits in PTR-MS work. © 2012 American Chemical Society.

Gonzalez-Mendez R.,University of Birmingham | Reich D.F.,KORE Technology Ltd | Mullock S.J.,KORE Technology Ltd | Corlett C.A.,KORE Technology Ltd | Mayhew C.A.,University of Birmingham
International Journal of Mass Spectrometry | Year: 2015

A novel thermal desorption unit (TDU) has been developed and specifically designed for the detection of trace quantities of explosives using a proton transfer reaction mass spectrometer (PTR-MS). For the first time details on recovery times and instrumental limits of detection for the screening of explosives with this TDU/PTR-MS system are reported. We demonstrate that traces (nanograms or less) of explosives deposited on swabs are desorbed within less than a second upon insertion into the TDU. For a short period of time (seconds) a concentration "pulse" of an explosive enters the drift (reaction) tube of the PTR-MS. This temporal concentration pulse of material is monitored in real-time by recording the product ion intensities for a given explosive as a function of time. By changing the reduced electric field in the drift tube region of the PTR-MS, we demonstrate how selectivity can be improved. This study demonstrates that the TDU/PTR-MS instrument meets security application criteria in terms of sensitivity, selectivity and recovery times. © 2015 Elsevier B.V. All rights reserved.

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