取10.00 g样品，加入20 mL二乙烯三胺五乙酸-氯化钙-三乙醇胺（DTPA-CaCl₂-TEA）浸提剂（DTPA、CaCl₂、TEA的浓度分别为0.005，0.01，0.1 mol·L^-1，酸度为pH 7.3±0.2），置于恒温振荡箱中，于（20±2）℃以180 r·min^-1振荡2 h，以提取有效铜、锌、铁、锰、硫。用滤纸过滤，采用电感耦合等离子体原子发射光谱法进行测定。结果显示：铜、锌、铁、锰、硫的质量浓度均在一定范围内与其对应的发射强度呈线性关系，检出限（3.143s）分别为0.01，0.02，0.02，0.01，0.1 mg·kg^-1。邀请了8家有资质的实验室进行精密度协作试验，确定了方法的重复性限和再现性限。方法用于12种土壤标准物质的分析，其中，有效铜、锌、铁、锰的测定值均在认定值的不确定度范围内，有效硫的测定值和行业标准方法的基本一致（农用地土壤有效态标准物质）或在认定值的不确定度范围内（土壤有效态标准物质和黄土土壤有效态标准物质）。

A portion of the sample (10.00 g) was mixed with 20 mL of diethylenetriamine pentaacetic acid-calcium chloride-triethanolamine (DTPA-CaCl₂-TEA) extractant (the concentrations of DTPA, CaCl₂ and TEA were 0.005, 0.01, 0.1 mol·L^-1 respectively, and the acidity was pH 7.3±0.2), and the mixture was placed into a constant temperature oscillation box to oscillate at 180 r·min^-1 for 2 h with oscillation temperature of (20±2)℃ for extraction of bioavailable forms of copper, zinc, iron, manganese and sulfur. After filtering with filter paper, the filtrate was determined by inductively coupled plasma atomic emission spectrometry. As showed by results, linear relationships between mass concentration of copper, zinc, iron, manganese and sulfur and emission intensity were kept in definite ranges, with detection limits (3.143s) of 0.01, 0.02, 0.02, 0.01, 0.1 mg·kg^-1 respectively. Eight qualified laboratories were invited to conduct precision collaborative test, and the reproducibility limits and reproducibility limits of this method were determined. The proposed method was applied to the analysis of 12 soil reference substances. The determined values of bioavailable forms of copper, zinc, iron and manganese were within the uncertainty ranges of the certified values, and the determined values of bioavailable form of sulfur were basically consistent with those provided by the industry standard methods (for agricultural soil available reference substances) or within the uncertainty ranges of the certified values (for soil available reference substances and loess soil available reference substances).