To establish a method for the determination of 22 kinds of organophosphate esters (OPEs) compounds in fish meat by ultra performance liquid chromatography-tandem mass spectrometry.

Samples were extracted by ultrasonic treatment with 0.1% formic acid-acetonitrile solution, and the extracts were purified through an HLB-Prime solid-phase extraction column. The samples were then dissolved in a nitrogen-blowed 0.5 mL mixture of 50% acetonitrile-0.1% formic acid before detection. The A phase (acetonitrile) and the B phase (2 mmol/L ammonium formate aqueous solution) were used as the mobile phase for gradient elution, with a flow rate of 0.2 mL/min and an injection volume of 2 μL. Multiple reaction monitoring (MRM) mode was employed for detection. The target compounds were separated on an ACQUITY UPLC® BEH C₁₈ chromatographic column (100 mm×2.1 mm, 1.7 μm) and detected via MRM in electrospray positive (18 kinds of OPEs) and negative (4 kinds of OPEs) ion modes, with isotope internal standard quantification.

Through optimization of chromatographic conditions, baseline separation was achieved for all 22 kinds of OPEs compounds. The 22 kinds of OPEs compounds exhibited good linearity within the range of 0.5–50.0 μg/L, with correlation coefficients all greater than or equal to 0.997. The limits of detection were 0.1–0.2 μg/kg, and the limits of quantitation were 0.3–0.6 μg/kg. The spiked recovery rates at low, medium and high concentration levels in fish meat ranged from 77.4% to 109.3%, with relative standard deviations (n=6) ranging from 1.8% to 8.6%. Using the established method, 7 fish meat samples were analyzed, and the detection rate of OPEs was 71.4%, and the residue of triethyl phosphate (TEP) in the sole was 29.60 μg/kg.

The method is simple, reliable, sensitive, reproducible and covers a wide range of OPEs, which is suitable for the detection of OPEs in fish meat.