Solid-Phase Microextraction Combined with GC-MS for Determination of Diquat and Paraquat Residues in Water

摘要

We have developed a method for the determination of diquat (DQ) and paraquat (PQ) in aqueous samples and applied it to environmental water samples. The method involves sodium borohydride-nickel chloride (NaBH4-NiCl2) reduction and headspace solid-phase microextraction of the perhydrogenated products. GC-MS in SIM mode was used to identify and quantify the analytes. The conditions affecting the reduction and extraction were investigated. The optimum conditions for reduction were: 100 mg NaBH4, 200 mu L 10 % (w/v) NiCl2, and 90 degrees C for 30 min. For extraction, the SPME fiber was exposed for 20 min at 60 degrees C; 1 mL 10 % NaCl (w/v) solution was added to the sample vial. Under these conditions, intra-day and inter-day precision for the target analytes were 1.21-6.21 % and 1.14-6.26 %, respectively. The detection limits for DQ and PQ in water were 0.1 ng mL(-1). Recovery of DQ and PQ were between 91.28 and 100.34 %. The method is easy, sensitive, and environmentally friendly.