High-Sensitivity Micro-Gas Chromatograph-Photoionization Detector for Trace Vapor Detection

Rapid in situ detection and analysis of trace vapor concentrations at a sub-parts per billion to parts per trillion level remains a challenge for many applications such as indoor air-quality analysis and detection of explosives and narcotics. Micro-gas chromatography (μGC) together with a micro-photoionization detector (μPID) is a prominent method for portable analysis of complex vapor mixtures, but current μPID technology demonstrates poor detection performance compared to benchtop flame ionization detectors (FIDs). This work demonstrates the development of a significantly improved μPID with a sub-picogram detection limit (as low as ∼0.2 pg) comparable to or exceeding that of a benchtop FID, with a large linear dynamic range (>4 orders of magnitude) and robustness (high stability over 200 h of plasma activation). Based on this μPID, a complete μGC-PID system was built and tested on standard sample chromatograms in a laboratory setting to show the system's analytical capabilities and the detection limit down to sub-parts per trillion concentrations (as low as 0.14 ppt). Practical in-field chromatograms on breath and car exhaust were also generated to demonstrate applicability for in situ experimentation. This work shows that μGC-PID systems can be competitive with traditional GC-FID methods and thus opens a door to rapid trace vapor analysis in the field.