Keywords: 
• organophosphorus flame retardants /
• automation /
• tandem mass spectrometry /
• freshwater fish

Abstract: An analytical method for the determination of 10 organophosphorus flame retardants (OPFRs) in freshwater fish samples was developed using automated equipment for pretreatment and gas chromatography-tandem mass spectrometry (GC-MS/MS) for quantification. In the present method, the samples were extracted using automatic soxhlet extraction system, and then a two-step clean-up (including automatic gel permeation chromatography (GPC) and florisil) was used to purify the extract. Finally, the GC-MS/MS was used for qualitation and quantitation by multi-reaction monitoring (MRM) mode. Experimental results showed that the best collection time of the automatic GPC system was from 900 to 1 680 seconds using ethyl acetate and hexane mixture (1:1, V/V) as mobile phase at a flow rate of 5.0 mL·min^-1. The method detection limits ranged from 0.002 ng·g^-1 to 0.192 ng·g^-1 wet weight, and the recoveries were in the range of 48.7%-122%, with relative standard deviations (RSDs) of less than 10% except for triethylphosphate (TEP) (17.7%) and tris(1,3-dichloropropyl) phosphate (TDCP) (11.9%). The developed method was applied to determine the OPFRs in freshwater fish collected from an outlet of a sewage treatment plant in the East River. The recoveries of d27-TBP spiked in the samples ranged from 82.4% to 114%, and the total concentrations of OPFRs in the samples ranged from not detected to 6.41 ng·g^-1 wet weight.