四酸微波消解-电感耦合等离子体原子发射光谱法测定土壤中6种重金属元素

Determination of Six Heavy Metal Elements in Soil by Inductively Coupled Plasma Atomic Emission Spectrometry after Microwave Digestion with Four Acids

建立了四酸微波消解-电感耦合等离子体原子发射光谱法(ICP-AES)测定土壤中6种重金属元素的方法。取0.10~0.20 g土壤样品用少量水润湿,加入6 mL硝酸、2 mL盐酸、1 mL氢氟酸和1 mL 30%(质量分数,下同)过氧化氢溶液,静置15 min使其充分反应,置于微波消解仪中按升温程序消解。消解液置于电热板上以140℃加热至溶液近干,用1%(体积分数)硝酸溶液溶解残渣并将其定容至25 mL,按优化的ICP-AES条件分析。所选的Pb、As、Ni、Cu、Zn、Cr的分析谱线分别为220.353,189.042,231.604,327.396,213.856,267.716 nm。结果显示:6种元素的质量浓度分别在1.00 mg·L^(-1)(Pb、As、Cu、Ni)内和2.00 mg·L^(-1)(Cr、Zn)内与其对应的光谱响应值呈线性关系,检出限(3s)为0.29~5.76μg·L^(-1);对标准样品进行6次重复测定,测定值的相对标准偏差为0.60%~2.6%,测定值与认定值基本一致。

A method for the determination of six heavy metal elements in soil by ICP-AES after microwave digestion with four acids was established. 0.10-0.20 g of soil samples were wetted with a small amount of water, added with 6 mL of nitric acid, 2 mL of hydrochloric acid, 1 mL of hydrofluoric acid and 1 mL of 30%(mass fraction) hydrogen peroxide solution. The mixture was kept under steady condition for 15 min to make it to fully react, and placed in a microwave digestion apparatus for digestion according to the temperature program. The digestion solution was heated on a hot plate at 140 ℃ until the solution was nearly dry. The residue was dissolved and diluted to 25 mL with 1%(volume fraction) nitric acid solution, and detected under the optimized ICP-AES conditions. The selected analytical spectral lines of Pb, As, Ni, Cu, Zn and Cr were 220.353, 189.042, 231.604, 327.396, 213.856, 267.716 nm, respectively. The results showed that the mass concentrations of the six elements within 1.00 mg·L^(-1)(for Pb, As, Cu, Ni) and 2.00 mg·L^(-1)(for Cr, Zn) were linearly related to the corresponding spectral response values, with detection limits(3s) in the range of 0.29-5.76 μg·L^(-1). The standard sample was analyzed 6 times repeatedly by the proposed method, giving RSDs of the determined values in the range of 0.60%-2.6%, and the determined values were basically consistent with the certified values.