提出了恒温摇床提取-电感耦合等离子体质谱法(ICP-MS)测定土壤中有效态镉含量的方法。将土壤样品放至搪瓷盘中,摊薄至2 cm厚左右,自然风干,研磨,过2 mm尼龙筛。称取过筛后的土壤样品5.00 g置于50 mL具塞离心管中,加入25 mL提取剂,将其放入恒温摇床中,设置提取温度为20~25℃,水平振荡频率为200 r·min^-1,提取时间为100 min。提取结束后,取出,离心,用0.45 μm水系微孔滤膜过滤,弃去最初的5~6 mL,收集续滤液。移取5.00 mL续滤液至25 mL比色管中,用1%(体积分数)硝酸溶液定容,按照ICP-MS仪器工作条件进行测定。结果显示:镉的质量浓度在0.50~100 μg·L^-1内与其对应的响应值呈线性关系,检出限(3.143s)为0.001 mg·kg^-1;对土壤国家标准物质进行测定,测定值在认定值范围内,测定值的相对标准偏差(n=6)为3.1%~5.0%。方法用于实际土壤样品分析,并与GB/T 23739-2009方法进行比对,计算t_0.05,8为1.145,说明两种方法的测定结果无显著性差异。

A method for the determination of available Cd in soil by inductively coupled plasma mass spectrometry (ICP-MS) with constant temperature shaker extraction was proposed. Soil sample was put into a enamel dish and spread out to about 2 cm of thickness for drying naturally. After grinding and passing through a 2 mm nylon sieve, 5.00 g of soil sample was placed in a 50 mL-plug centrifuge tube, and 25 mL of extraction agent was added. The above solution was extracted by constant temperature shaker with extraction temperature of 20-25 ℃, horizontal oscillation frequency of 200 r·min^-1 and extraction time of 100 min. After extraction, the sample solution was centrifuged and filtered with 0.45 μm water microporous membrane. The first 5-6 mL of filtrate was discarded, and the subsequent filtrate was collected. The subsequent filtrate (5.00 mL) was transferred to a 25 mL-colorimetric tube, and 1% (φ) nitric acid solution was used to fix volume. ICP-MS was used for analysis according to the working conditions of the instrument. As shown by the results, linear relationship between value of mass concentration of Cd and its response value was kept in the range of 0.50-100 μg·L^-1, with detection limit (3.143s) of 0.001 mg·kg^-1. Soil national standard substances were determined, and the determined values were within the ranges of certified values, with RSDs (n=6) of the determined values in the range of 3.1%-5.0%. This method has been applied to the analysis of actual soil samples, and compared with GB/T 23739-2009. The results showed that there was no significant difference between the two methods with value of t_0.05,8 of 1.145.