Optimizations of large volume-direct aqueous injection-gas chromatography to monitor volatile organic compounds in surface water

Abstract

For the trace determination and automated continuous monitoring of volatile organic compounds (VOCs) in surface water, a large volume-direct aqueous injection-gas chromatography (LV-DAI-GC) method was optimized for the following parameters: packed sorbent, inlet temperature, injection volume, detector configurations and sample renewal. Using the packed sorbent lab-made with lithium chloride and diatomite 101 W, at an inlet temperature of 140 °C, 14 typical VOCs were separated from a 50 μL water matrix in 0.3 min. Coupled with a flame ionization detector (FID), an electron capture detector (ECD) and a flame photometric detector (FPD), the method quantification limits (MQLs) for the 14 typical VOCs were 0.008–7 μg L⁻¹. For the samples from the simulated VOC pollution incidents, the relative standard deviations (RSDs) and relative errors (REs) were 5.9% and 9.5%, respectively. For real samples from a river polluted with VOCs, the quantitative results using LV-DAI-GC agreed well with those of purge-and-trap GC (PT-GC). The optimized reliable LV-DAI-GC could be applied to the automated continuous monitoring of VOCs in surface water and an early warning of VOC pollution incidents.