Low-cost photoionization sensors as detectors in GC × GC systems designed for ambient VOC measurements

• Published in: The Science of the total environment 2019-05, Vol.664, p.771-779
• Main Authors: Pang, Xiaobing, Nan, Haijun, Zhong, Jinping, Ye, Daiqi, Shaw, Marvin D., Lewis, Alastair C.
• Format: Article
• Language: English
• Subjects: Flame ionization detector (FID); Gas chromatography (GC); Photo-ionization detector (PID); Quadruple time-of-flight mass spectrometry (Q-TOF-MS); Two-dimensional gas chromatography (GC × GC); Volatile organic compounds (VOCs)
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2019.01.348

Conventional volatile organic compound (VOC) monitoring based on thermal desorption - gas chromatography–mass spectrometry (TD-GC–MS) or gas chromatography-flame ionization detector (TD-GC-FID) is relatively cumbersome and expensive. In this study commercial off the shelf low-cost and low-power photo-ionization detector (PID) sensors are used as simple detectors in VOC analysis systems based on GC, including a miniaturised GC × GC device with portable, low-cost, and low-energy-consumption features. PID sensors produce a voltage signal positively proportional to VOC concentration, which when incorporated into a TD-GC system gave limit of detection of 0.02 ppbV for isoprene. To test PID performance in real-world applications, PID sensors were deployed as (i) a second alternative detector in a GC-Quadruple Time Of Flight Mass spectrometry (GC-Q-TOF-MS), and (ii) the main detector in a compact two-dimensional gas chromatograph (GC × GC). PID sensors with 10.6 eV and 11.7 eV lamps were used to measure eight toxic chemicals including organic sulfide and organic phosphonates via GC; two species were ionized by a 10.6 eV lamp and four species by the 11.7 eV lamp. Commercially available low-cost PIDs designed for standalone could be straightforwardly and effectively re-used as detectors in compact GC × GC systems, in this work showing excellent VOC sensitivity, fast response and low operational demands compared to comparable field instruments based on GC-FID or MS. [Display omitted] •PID as detector of a compact GC × GC shows similar performance with GC-FID.•PID sensor acts as a detector in a GC-Q-TOF-MS for VOC measurements.•PID lamps show different ionization effect on organic insecticides.