离子色谱分离-电感耦合等离子体质谱联用法测定肉类食品中无机砷

ICP-MS Determination of Inorganic Arsenic in Meat Food with IC Separation

粉碎的肉类食品试样用水分散后经超声提取40 min,于提取液中加乙酸（3＋97）使蛋白质沉淀析出,并在4℃用高速离心法予以分离。取上层清液用经0.45μm滤膜过滤,滤液中的无机砷（Ⅲ及Ⅴ）和有机胂,即甲基胂（MA）和二甲基胂（DMA）通过IonPac AS 18阴离子色谱柱予以分离。用不同浓度的氢氧化钾溶液作流动相进行梯度淋洗,使上述4种形态的砷在碱性溶液中分别以阴离子状态而分离。用电感耦合等离子体质谱法分别测定洗脱液中无机砷（Ⅲ及Ⅴ）的含量,两者的检出限依次为0.3,0.5μg.kg-1。以肉类食品为基体加入3种不同浓度的标准溶液,按试验方法分析后求得方法的回收率及精密度为①三价砷回收率在83.1%~93.3%之间,相对标准偏差（n=6）在3.3%~6.7%之间;②五价砷回收率在85.3%~97.6%之间,相对标准偏差（n=6）为3.1%~5.9%。

Sample of ground meat was dispersed with water,and extracted ultrasonically for 40 min.Acetic acid（3＋97） was added to the extract to precipitate protein which was separated by high speed centrifugation at 4 ℃.The supernatant was taken and filtered on 0.45 μm filtering membrane.IonPac AS 18 anion chromagraphic column was used for separation of inorganic arsenic（Ⅲ and Ⅴ） and organic arsenic compounds of methylarsine（MA） and dimethylarsine（DMA）.Potassium hydroxide solutions of different concentrations were used as mobile phase in gradient elution of the 4 species of arsenic in forms of their anions,in the alkaline solutions.The eluates were used for ICP-MS determination of inorganic As（Ⅲ） and As（Ⅴ）,with values of detection limits（3S/N） of 0.3 and 0.5 μg·kg-1,respectively.Tests for recovery and precision were made by standard addition method at 3 different concentration levels,the results obtained were as follows： ① for As（Ⅲ）,recovery 83.1% to 93.3%,RSD′s（n=6） 3.3% to 6.7%;② for As（Ⅴ）,recovery 85.3% to 97.6%,RSD′s（n=6） 3.1% to 5.9%.