Fast Determination of Monocyclic Aromatic Hydrocarbons in Ambient Air Using a Portable Gas Chromatography-Photoionization Detector.

Many air sampling methods are time consuming and require complex pre-treatment steps. Gas chromatography-photoionization detector (GC-PID) is a rapid method for sampling and analysis. However, although it has been used in a number of studies, its operating conditions and performance parameters have not been optimized systematically. In this study, a GC-PID method for analysis of monocyclic aromatic hydrocarbons in gas samples without pre-concentration or enrichment was developed and optimized. This GC-PID can perform both online and off-line analysis. In online analysis, the sample was pumped directly into a Teflon sample loop (pumped online injection), which resulted in minimal loss of sample. The optimum parameters were as follows: 30-s pumping time, 10 mL min of carrier gas flow rate, and 40 °C oven temperature. GC-PID was applied to analysis of benzene, toluene and xylene. The calibration curves showed good linearity for online analysis. The results obtained by GC-PID were accurate and reliable, with all the correlation coefficients ≥0.9972 and all the relative standard deviations <3%. A mixture of benzene, toluene, and o-, m-, and p-xylenes was separated satisfactorily in 10 min, except for m- and p-xylene. The performance of the portable GC-PID was compared with that of an ATD-GC-FID for quantification of benzene, toluene and xylene in calibration gas samples, and benzene, toluene, ethylbenzene, and the o-, m-, and p-xylenes in outdoor ambient air. The results indicated that GC-PID with pumped online injection was stable and accurate for analysis of these monocyclic aromatic hydrocarbons. [ABSTRACT FROM AUTHOR]