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 (mu GC) together with a micro-photoionization detector (mu PID) is a prominent method for portable analysis of complex vapor mixtures, but current mu PID technology demonstrates poor detection performance compared to benchtop flame ionization detectors (FIDs). This work demonstrates the development of a significantly improved mu PID with a sub-picogram detection limit (as low as similar to 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 mu PID, a complete mu GC-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 GC-PID systems can be competitive with traditional GC-FID methods and thus opens a door to rapid trace vapor analysis in the field.