Hand-held portable desorption atmospheric pressure chemical ionization ion source for in situ analysis of nitroaromatic explosives.
A novel, lightweight (0.6 kg), solvent- and gas-cylinder-free, hand-held ion source based on desorption atmospheric pressure chemical ionization has been developed and deployed for the analysis of nitroaromatic explosives on surfaces in open air, offering portability for in-field analysis. A small, inexpensive, rechargeable lithium polymer battery was used to power the custom-designed circuitry within the device, which generates up to ±5 kV dc voltage to ignite a corona discharge plasma in air for up to 12 h of continuous operation, and allowing positive- and negative-ion mass spectrometry. The generated plasma is pneumatically transported to the surface to be interrogated by ambient air at a rate of 1-3.5 L/min, compressed using a small on-board diaphragm pump. The plasma source allows liquid or solid samples to be examined almost instantaneously without any sample preparation in the open environment. The advantages of low carrier gas and low power consumption (<6 W), as well as zero solvent usage, have aided in developing the field-ready, hand-held device for trigger-based, "near-real-time" sampling/ionization. Individual nitroaromatic explosives (such as 2,4,6-trinitrotoluene) can be easily detected in amounts as low as 5.8 pg with a linear dynamic range of at least 10 (10-100 pg), a relative standard deviation of ca. 7%, and an R(2) value of 0.9986. Direct detection of several nitroaromatic compounds in a complex mixture without prior sample preparation is demonstrated, and their identities are confirmed by tandem mass spectrometry fragmentation patterns.
Department of Electrical Engineering and Electronics, University of Liverpool , Liverpool L69 3GJ, U.K.|Q-Technologies Ltd. , 100 Childwall Road, Liverpool L15 6UX, U.K.
Fred P M
FP
Jjunju
Department of Electrical Engineering and Electronics, University of Liverpool , Liverpool L69 3GJ, U.K.
Simon
S
Maher
Chemistry Department, Purdue University , West Lafayette, Indiana 47907, United States.
Anyin
A
Li
M4I, the Maastricht Multi Modal Molecular Imaging Institute, University of Maastricht , Universiteitssingel 50, 6229 ER Maastricht, The Netherlands.
Sarfaraz U
SU
Syed
Department of Electrical Engineering and Electronics, University of Liverpool , Liverpool L69 3GJ, U.K.|Q-Technologies Ltd. , 100 Childwall Road, Liverpool L15 6UX, U.K.
Barry
B
Smith
M4I, the Maastricht Multi Modal Molecular Imaging Institute, University of Maastricht , Universiteitssingel 50, 6229 ER Maastricht, The Netherlands.
Ron M A
RM
Heeren
Department of Electrical Engineering and Electronics, University of Liverpool , Liverpool L69 3GJ, U.K.|Q-Technologies Ltd. , 100 Childwall Road, Liverpool L15 6UX, U.K.
Stephen
S
Taylor
Chemistry Department, Purdue University , West Lafayette, Indiana 47907, United States.
R Graham
RG
Cooks