Determination of 9 Organophosphorus Flame Retardants in Vegetables by High Performance Liquid Chromatography-Tandem Mass Spectrometry

A method for the determination of 9 organophosphorus flame retardants in vegetables was established by high performance liquid chromatography-tandem mass spectrometry. The QuEChERS method was used for sample pretreatment. The sample (5.0 g) was extracted with 10 mL of a mixture of acetonitrile and acetone at volume ratio of 4∶1, the water of which were removed, and the analytes were purified, blown to dryness by nitrogen and redissolved with 0.5 mL methanol. The chromatographic separation was performed by using Waters ACQUITY UPLC^® BEH C₁₈ chromatographic column as stationary phase, and the mixtures of aqueous solution containing 0.1% (φ) formic acid and methanol solution containing 0.1% (φ) formic acid at different volume ratios were used as mobile phase for gradient elution. ESI⁺ and the mode of multireaction monitoring (MRM) were adopted in MS/MS. Ion pair and retention time were used for qualitative analysis, and external standard method for quantitative analysis. The results showed that linear relationships of mass concentrations of 9 organophosphorus flame retardants were found in the definite ranges, with detection limits (3S/N) in the range of 0.01-15 μg·kg^-1. Tests for recovery were made by standard addition method, giving results in the range of 60.0%-120%, and RSDs of the determined values (n=5) all less than 10%. This method was used to analyze the 7 Vegetable samples, and the detection rate of triethyl phosphate (TEP) was up to 100%.