称取经匀浆处理后的样品1.000 0 g，加入48 mL的0.5 mmol·L^-1碳酸铵溶液-甲醇（99+1）混合液（pH 7.8），涡旋混匀后，超声提取40 min，加入2 mL的3%（φ）乙酸溶液，于4℃静置5 min，以8 000 r·min^-1转速于4℃离心10 min，取上清液过0.45 μm滤膜，收集2 mL滤液，采用Hamilton PRP-X100阴离子分析柱（250 mm×4 mm，10 μm）进行分离，以pH 7.8的0.5 mmol·L^-1碳酸铵溶液-甲醇（99+1）混合液及pH 8.5的20 mmol·L^-1磷酸氢二铵溶液为流动相进行梯度洗脱，采用电感耦合等离子体质谱法测定洗脱液中的三价砷[（As（Ⅲ）]、五价砷[（As（Ⅴ）]、砷甜菜碱（AsB）、一甲基砷（MMA）和二甲基砷（DMA）。5种形态的砷的线性范围在100 μg·L^-1以内，检出限（3S/N）为0.2~0.6 μg·L^-1，加标回收率为89.6%~102%，测定值的相对标准偏差（n=6）为0.11%~3.8%。

The homogenized sample (1.000 0 g) was added into 48 mL of 0.5 mmol·L^-1 ammonium carbonate solution-methanol (99+1) solution (pH 7.8). The mixture was mixed well by vortexing, and then ultrasonically extracted for 40 min. After 2 mL of 3% (φ) acetic acid solution was added, the mixture was allowed to stand at 4℃ for 5 min, and then centrifuged at 8 000 r·min^-1 for 10 min at 4℃. The supernatant was filtrated with a 0.45 μm filter, and 2 mL of the filtrate was taken and separated on a Hamilton PRP-X100 anion analytical column (250 mm×4 mm, 10 μm), with 0.5 mmol·L^-1 ammonium carbonate solution-methanol (99+1) solution (pH 7.8) and 20 mmol·L^-1 diammonium hydrogen phosphate solution (pH 8.5) as mobile phase for gradient elution. Trivalent arsenic[As (Ⅲ)], pentavalent arsenic[As (Ⅴ)], arsenic betaine (AsB), monomethyl arsenic (MMA) and dimethyl arsenic (DMA) in the eluate were determined by inductively coupled plasma mass spectrometry. The same linearity range of five kinds of arsenic species was within 100 μg·L^-1, and the detection limits (3S/N) were in the range of 0.2-0.6 μg·L^-1. Values of recovery obtained by standard addition method were in the range of 89.6%-102%, and RSDs (n=6) were in the range of 0.11%-3.8%.