王水加辅助酸微波消解—原子荧光测定土壤砷、硒

Determination of Soil Arsenic and Selenium by Atomic Fluorescence Under Microwave Digestion with Aqua Regia plus Assisted Acid

采用标样法,研究微波消解条件下,王水加辅助酸(双氧水、高氯酸、氢氟酸)消解土壤,氢化物原子化-原子荧光法测定土壤全As、全Se的最佳消解酸体系和方法.含HF或氟化物的消解液对As和Se的测定有强烈的非原子荧光干扰;加HClO_4处理,因在正常的微波消解和赶酸条件下均无法完全去除,其残留物可能对待测元素的还原—氢化物生成过程发生阻碍而产生严重干扰;而王水加H_2O_2辅助氧化处理,既保证土壤矿物完全被打开,又能彻底氧化有机质,同时也避免了氧化剂残留对后续还原反应的干扰,采用土壤标样做回收率测定,As、Se的回收率分别为102%、112%,标准偏差和变异系数均满足土壤微量元素测定要求.

In this paper,it used the method of standard sample,combined with microwave digestion system,digestion soil at aqua regia plus auxiliary acid(hydrogen peroxide,perchloric,hydrofluoric acid)system,determining the whole Arsenic and Selenium in the solution by Hydride Generation-Atomic Fluorescence spectrometry to choose the best digestion acid system and method.The results showed that:digestion solution contained HF for the determination of As and Se by AFS has a strong interference;after adding HClO4,because in the normal microwave digestion and exclude the acid conditions which could not completely be removed,the residues might be obstacle the reduction and hydride generation process of determined elements as to bring Serious interference;while aqua regia plus H2O2 assisted oxidation process,that ensured the mineral soil was completely open,also made organic matter thorough oxidation,and avoided residual oxidant affect subsequent reduction reaction.Using soil standard sample made recoveries,As and Se recoveries were 102%,112%respectively,standard deviation and coefficient of variation are satisfied the measured requirements of trace elements in the soil.