LC-ICP-MS技术分析土壤中的砷形态

Speciation analysis of arsenic in soils by LC-ICP-MS

建立了土壤中亚砷酸根(As~Ⅲ),砷酸根(As~Ⅴ),一甲基砷酸(MMA),二甲基砷酸(DMA)的液相色谱-电感耦合等离子体质谱(LC-ICP-MS)在线联用检测方法。以磷酸为提取剂,抗坏血酸为还原剂,水浴加热1h可以有效提取土壤中的As;4种砷形态经过Hamilton PRP-x100阴离子交换柱,用15mmol/L的(NH_4)_2HPO_4以1mL/min的流速进行洗脱分离。实验结果表明,3种土壤标准物质的As提取率在86.61%~108.06%之间,平均提取率为99.94%,且该方法检测的相对误差<10%,RSD(n=3)不大于3.69%。同时,对比了Hamilton PRP-x100阴离子交换柱与IonPac AS19阴离子交换柱对4种砷形态的分离效果。

The online method for analysis of arsenite（AsⅢ）,arsenate（AsⅤ）,methyl arsenate（MMA）,dimethyl arsenate（DMA）in soil was established through liquid chromatography combined with inductively coupled plasma mass spectrometry（LC-ICP-MS）.Arsenic could be efficiently extracted by water bath heating in an hour when phosphoric acid was used as the extractant and ascorbic acid was adopted as the reducing agent.Then the four arsenic species were eluted and online separated by anionic PRP-x100 Hamilton exchange column with 15 mmoL/L（NH4）2 HPO4 at the velocity of 1 mL/min.The experimental results showed that the extraction ratios for arsenic in three soil standard reference materials were between 68.61% and 108.06% ,and the average extraction rate was 99.94% .The relative error of this method was lower than 10% and RSD（n=3）was less than 3.69% .Meanwhile,the separation effects of the four arsenic species using the PRP-x100 Hamilton anion exchange column and the AS19 IonPac anion exchange column were compared.