Jjunju Fred P M, Maher Simon, Li Anyin, Syed Sarfaraz U, Smith Barry, Heeren Ron M A, Taylor Stephen, Cooks R Graham
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.
Anal Chem. 2015 Oct 6;87(19):10047-55. doi: 10.1021/acs.analchem.5b02684. Epub 2015 Sep 9.
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.
一种新型的、轻便的（0.6千克）、无需溶剂和气瓶的手持式离子源已被开发出来并应用于户外表面硝基芳香族炸药的分析，为现场分析提供了便携性。该设备使用一个小型、廉价的可充电锂聚合物电池为定制设计的电路供电，该电路可产生高达±5 kV的直流电压，在空气中引发电晕放电等离子体，可连续运行长达12小时，并支持正离子和负离子质谱分析。产生的等离子体通过一个小型车载隔膜泵以1-3.5 L/min的速率被压缩空气输送到待检测的表面。该等离子体源允许在开放环境中几乎无需任何样品制备即可对液体或固体样品进行即时检测。低载气、低功耗（<6 W）以及零溶剂使用的优点有助于开发出一种适用于现场的、手持式的基于触发的“近实时”采样/电离设备。单个硝基芳香族炸药（如2,4,6-三硝基甲苯）的检测限低至5.8 pg，线性动态范围至少为10（10-100 pg），相对标准偏差约为7%，R(2)值为0.9986。展示了在无需预先样品制备的情况下直接检测复杂混合物中几种硝基芳香族化合物的能力，并且通过串联质谱碎片模式确认了它们的身份。
