Abstract: A multi-residue analytical method for the simultaneous determination of persistent organic pollutants (POPs) in rice samples was developed. POPs were extracted from rice with ethyl acetate/n-hexane(80∶20,v/v) by sonication, and determined by gas chromatography with electron impact mass spectrometric detection in the selected ion monitoring mode. A fused silica capillary column DB-35MS (30 m× 0.25 mm i.d. ×0.25 μm) was employed. Operating conditions were as follows: injector port temperature, 300 °C; column temperature, programming; carrier gas, helium; flow rate, 1.0 mL/min; sample size, 1 μL with splitless injection. The mass spectrometric detector (MSD) was operated in electron impact ionization mode with an ionizing energy of 70 eV. Analysis was performed with selected ion monitoring (SIM) using one target and one or two qualifier ion.POPs were confirmed by their retention times, their qualifier and target ions, and their qualifier/target abundance ratios. Recovery studies were performed at 0.05, 0.1, and 0.5 mg/L spiked levels of each POPs, and the recoveries obtained ranged from 81.99% to 100.60% with relative standard deviations between 2.37% and 18.48%. The detection limits of the method ranged from 0.1 to 5 ng/g for the different POPs except endrin, trans-chlordane and cis-chlordane. The results show that the method developed is sensitive and reliable.

Key words: persistent organic pollutants, rice , gas chromatography/mass spectrometry