Interfacing an Ion Mobility Spectrometry Based Explosive Trace Detector to a Triple Quadrupole Mass Spectrometer

• Published in: Analytical chemistry (Washington) 2011-11, Vol.83 (22), p.8596-8603
• Main Authors: Kozole, Joseph, Stairs, Jason R, Cho, Inho, Harper, Jason D, Lukow, Stefan R, Lareau, Richard T, DeBono, Reno, Kuja, Frank
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Chemistry; Electric fields; Exact sciences and technology; General, instrumentation; Ions; Mass spectrometry; Mass Spectrometry - instrumentation; Spectrometric and optical methods; Trinitrotoluene - analysis
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac201999a

Hardware from a commercial-off-the-shelf (COTS) ion mobility spectrometry (IMS) based explosive trace detector (ETD) has been interfaced to an AB/SCIEX API 2000 triple quadrupole mass spectrometer. To interface the COTS IMS based ETD to the API 2000, the faraday plate of the IMS instrument and the curtain plate of the mass spectrometer were removed from their respective systems and replaced by a custom faraday plate, which was fabricated with a hole for passing the ion beam to the mass spectrometer, and a custom interface flange, which was designed to attach the IMS instrument onto the mass spectrometer. Additionally, the mass spectrometer was modified to increase the electric field strength and decrease the pressure in the differentially pumped interface, causing a decrease in the effect of collisional focusing and permitting a mobility spectrum to be measured using the mass spectrometer. The utility of the COTS-ETD/API 2000 configuration for the characterization of the gas phase ion chemistry of COTS-ETD equipment was established by obtaining mass and tandem mass spectra in the continuous ion flow and selected mobility monitoring operating modes and by obtaining mass-selected ion mobility spectra for the explosive standard 2,4,6 trinitrotoluene (TNT). This analysis confirmed that the product ion for TNT is [TNT – H]−, the predominant collision-induced dissociation pathway for [TNT– H]− is the loss of NO and NO2, and the reduced mobility value for [TNT – H]− is 1.54 cm2V–1 s–1. Moreover, this analysis was attained for sample amounts of 1 ng and with a resolving power of 37. The objective of the research is to advance the operational effectiveness of COTS IMS based ETD equipment by developing a platform that can facilitate the understanding of the ion chemistry intrinsic to the equipment.