Determination of 5 Arsenic Species in Livestock and Poultry Meat by High Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry

A method for the determination of 5 arsenic species, including of trivalent arsenic As(Ⅲ), pentavalent arsenic As(Ⅴ), dimethylarsenic (DMA), monomethylarsenic (MMA), arsenobetaine (AsB) in livestock and poultry meat by high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS) was proposed. The sample (1.000 g) was taken, and 10 mL of 10% (volume fraction) methanol solution containing 1% (volume fraction) nitric acid (as extractant) was added for extraction by ultrasound at 60 ℃ for 2.0 h. After cooling and centrifugation, an aliquot (5 mL) of the supernatant was taken and 5 mL of n-hexane was added. The mixed solution was shaken for 1 min, and centrifuged for 10 min. The upper n-hexane phase was discard, and 5 mL of n-hexane was added to repeat the above steps once. The lower clear solution was aspirated,and passed through a 0.45 μm filter membrane. Agilent ZORBAX SB-Aq column (250 mm×4.6 mm, 5 μm) was used as the separation column, and 20 mmol · L^-1 citric acid solution containing 5 mmol · L^-1 sodium hexanesulfonic acid was used as the mobile phase for isocratic elution of targets in the filtrate. It was shown that linear ranges of the standard curves for the 5 arsenic species were 2-50 μg · L^-1, with detection limits (3S/N) in the range of 0.1-0.2 μg · L^-1. Test for recovery was made on the actual sample by the standard addition method at 3 concentration levels, giving the recovery of 5 arsenic species in the range of 81.5%-101%, and RSDs (n=6) of the determined values were in the range of 1.3%-3.6%. The method was used to analyze 10 actual samples, in which detection rates of As(Ⅲ), DMA and AsB were higher, and the detected amounts of arsenic species in liver and kidney were higher than those in muscle, but they were far lower than the limit (0.5 mg · kg^-1) of total arsenic in meat and meat products set by GB 2762—2017.