Determination of organophosphate esters in water samples using an ionic liquid-based sol-gel fiber for headspace solid-phase microextraction coupled to gas chromatography-flame photometric detector.

A simple, low-cost and sensitive method for determining organophosphate esters (OPEs) in water samples has been developed based on headspace solid-phase microextraction (SPME) followed by gas chromatography-flame photometric detector. The ionic liquid (1-allyl-3-methylimidazolium tetrafluoroborate, [AMIM][BF4])-based coating was developed by sol-gel technology and employed for extracting analytes. The prepared coating performed stably at high temperatures (up to 335°C) and with a range of solvents. It can be used at least 200 times without an obvious decrease in extraction efficiency. The extraction capability of the new fiber was much higher than polydimethylsiloxane (PDMS), polydimethylsiloxane/divinylbenzene (PDMS/DVB) and polyacrylate (PA) fibers. The experimental parameters that influenced the extraction efficiency, including extraction time, extraction temperature, stirring rate and ionic strength were investigated and optimized. Under the optimal conditions, the method detection limits (S/N=3) were in the range of 0.7-12ngL(-1), and the limits of quantification (S/N=10) were between 1.0 and 28ngL(-1). The repeatability of a single fiber varied from 3.3 to 7.6% (intra-day precision, n=6) and 4.3 to 8.9% (inter-day precision, n=6). The reproducibility of fiber-to-fiber (n=6) was in the range of 3.1-9.4%. The proposed method was applied successfully for the determination of OPEs in lake water, wastewater, sewage treatment plant effluent, and tap water with recoveries varying from 75.2 to 101.8%. The results demonstrate that the proposed method is highly effective for analyzing OPEs in water samples.