液相色谱-电感耦合等离子体-质谱法分析海藻碘浓缩液中砷形态

目的 建立液相色谱-电感耦合等离子体质谱法(liquid chromatography-inductively coupled plasma mass spectrometry, LC-ICP-MS)测定海藻碘浓缩液中6种不同形态砷化合物的分析方法。方法 单因素实验确定对不同形态砷化合物LC-ICP-MS的分离条件, 包括流动相浓度、pH及洗脱方式。以总砷提取效率的高低评价三种不同的提取砷化合物的方法, 确定最佳方法。结果 以稀硝酸浸提的前处理方法的提取效果最佳, 提取效率为84.28%~92.99%；以25 mmol/L pH8.0磷酸二氢铵溶液和水作为流动相, 采用梯度洗脱的方式, 可以将6种砷形态完全分离，结果显示6种海藻碘样品中砷甜菜碱AsB含量较多, 而亚砷酸盐As(III)、砷酸盐As(V)和二甲基砷酸DMA含量较少, 未检测出砷胆碱AsC和一甲基砷酸MMA, 样品有毒砷含量占浓缩液总砷含量的2.01%~3.69%, 本方法加标回收率在80.4%~101.5%之间。结论 海藻碘浓缩液中砷形态的主要存在形式为AsB，本方法准确、简单，适合海藻碘浓缩液中砷形态分析。

Analysis of arsenic speciation in seaweed iodine concentrate solution by liquid chromatography-inductively coupled plasma-mass spectrometry

Objective To establish a method for determination of AsC, AsB, As(III), DMA, MMA and As(V) in seaweed iodine concentrate solution by liquid chromatography-inductively coupled plasma-mass spectrometry (LC-ICP-MS). Methods The single factor experiment was used to determine the separation conditions of different arsenic speciation by LC-ICP-MS, including mobile phase concentration, pH and elution mode. Three different extraction methods were evaluated by the extraction efficiency of total arsenic, and the best method was determined. Results The pre-treatment method with dilute nitric acid extraction has the best extraction effect (84.28%~92.99%). The gradient elution was carried out with ammonium dihydrogen phos-phate solution (25 mmol/L pH8.0) and water as mobile phase. Under such conditions, 6 kinds of arsenic speciation could be separated completely. The results showed that the content of AsB in the samples was higher, while the contents of As(III), As(V) and DMA were less, and the arsenic speciation of AsC and MMA were not detected. The toxic arsenic content of the sample accounted for 2.01%~3.69% of the total arsenic content of seaweed iodine concentrate solution. The recovery of this method was 80.4%~101.5%. Conclusion The main arsenic speciation existed in seaweed iodine concentrate solution is AsB. This method is accurate, simple and suitable for the analysis of arsenic speciation in seaweed iodine concentrate solution.