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Portable Pen-Probe Analyzer Based on Ion Mobility Spectrometry for in Situ Analysis of Volatile Organic Compounds Emanating from Surfaces and Wireless Transmission of the Acquired Spectra

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journal contribution
posted on 20.01.2021, 13:04 by Chun-Pei Shih, Kai-Chiang Yu, Hsuan-Ting Ou, Pawel L. Urban
The analysis of volatile organic compounds (VOCs) normally involves sample collection, sample transfer to laboratory, sample preparation, and the chromatographic separation of analytes. However, in some cases, it is impractical or impossible to collect samples prior to the analysis, while the analysis time has to be minimized. Ion mobility spectrometry (IMS) is an ideal technique for a rapid in situ chemical analysis. Here, we present a portable cloud-integrated pen-probe analyzer based on IMS and demonstrate its applications in the analysis of VOCs emanating from surfaces. The user approaches the pen-probe to a sampled surface and presses a button on the pen-probe. The analysis is then executed automatically. The VOCs are scavenged from the surface by a suction force and directed to a corona discharge atmospheric pressure chemical ionization source. The ions are separated in a drift tube according to their size and charge and then detected by a Faraday plate detector. The detector signal is amplified and digitized. The spectral data are deposited in the Internet cloud along with time and location data for further retrieval and processing. The platform incorporates a mobile Wi-Fi router for easy connectivity and a global positioning system module for geolocation. The prototype was developed using low-cost electronic modules (Arduino, Tinker Board S). It was further characterized using chemical standards. The limits of detection for pyrrolidine, 2,4-lutidine, and (−)-nicotine are 48.9, 2.30, and 416 nmol, respectively (amounts of substances placed on the sampling surface). The selected real specimens (nicotine patch, skin exposed to nicotine, fish sauce, and fried chicken) were also subjected to analysis yielding the characteristic ion mobility spectra.