高效液相色谱-电感耦合等离子体质谱法测定 大米中无机砷

目的建立高效液相色谱-电感耦合等离子体质谱法测定大米中无机砷的分析方法。方法采用两种前处理方法对大米中的无机砷进行提取,经高效液相色谱分离后,利用电感耦合等离子体质谱进行测定。同时对大米样品进行微波消解后测定其中的总砷,通过无机砷及有机砷的总和计算两种前处理方法的回收率,从而对前处理方法进行比较。对磷酸二氢铵、碳酸铵以及磷酸氢二铵等缓冲盐进行选择,并对p H值进行优化,确定最优的流动相条件。结果以12.5 mmol/L磷酸氢二铵作为流动相,调节流动相p H为8.5,流速为1 m L/min,可以将5种无机砷形态完全分离。对两种前处理方法进行比较,发现两种前处理方法的提取效率均大于87.5%,其中酸-热辅助提取法的提取效率相对更高。结论该方法准确、简单,适合大米中无机砷的测定。

Determination of inorganic arsenic in rice by high performance liquid chromatography-inductively coupled plasma mass spectrometry

Objective Inorganic arsenic in rice were extracted with two pre-treatment methods, then separated by high perfor -mance liquid chromatography(HPLC) and detected by inductively coupledplasma mass spectrometry ( ICP-MS). Method Two kinds of pretreatment methods were used to extract inorganic arsenic from rice. After separation by high performance liquid chromatography (HPLC), the samples were determined by inductively coupled plasma mass spectrometry (ICP-MS). At the same time, the total arsenic was determined by microwave digestion of rice samples. The recoveries of two pretreatment methods were calculated by the sum of inorganic arsenic and organic arsenic, and the pretreatment methods were compared. The buffer salts such as ammonium dihydrogen phosphate, ammonium carbonate and diammonium hydrogen phosphate were selected and the pH value was optimized to determine the optimum mobile phase conditions.Result In this method, 12.5 mmol / L diammonium hydrogen phosphate was used as the mobile phase, and the mobile phase was adjusted to pH 8.5 and the flow rate was 1 mL / min. Five kinds of inorganic arsenic species could be separated completely. The results showed that the extraction efficiency of the two pretreatment methods was higher than 87.5%, and the extraction efficiency of the acid - thermal assistant extraction method was higher.Conclusion The method is accurate, simple and suitable for the determination of inorganic arsenic in rice.