[Determination of trace pentachlorophenol and its sodium salt in animal-origin foods by QuEChERS-ultra performance liquid chromatography-tandem mass spectrometry].

A method was developed for the determination of trace pentachlorophenol and its sodium salt in animal-origin foods by modified QuEChERS-ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Sodium pentachlorophenolate in samples was converted to pentachlorophenol under acidic condition. The pentachlorophenol was extracted twice with acetonitrile containing 1% (v/v) acetic acid by ultrasonic extraction. The extracts were purified by dispersive solid-phase extraction. The usages of dispersive sorbents were optimized based on the recoveries and matrix effects. Chromatographic analysis was conducted on a Waters Acquity UPLC HSS T3 column with gradient elution. The pentachlorophenol was further analyzed by negative electrospray ionization under the multiple reaction monitoring mode. The recoveries at fortification levels of 1.0, 2.0 and 10.0 μg/kg in six matrices (pork, pork liver, chicken, fish, milk and egg) ranged from 73.2% to 108.4% with the relative standard deviations of 4.0%-14.8%. The limits of quantification (S/N>10) were 1.0 μg/kg. The method is simple, sensitive, accurate, economical and environmentally safe, and is suitable for the determination of the trace pentachlorophenol and its sodium salt in animal-origin foods.