电感耦合等离子体原子发射光谱法测定土壤中水溶性硫酸根

通常采用EDTA滴定法测定土壤中水溶性硫酸根,但该法操作繁琐、分析周期较长。为了适应大批量样品分析,实验通过对振荡浸取温度、时间、频率的优化,选择室温为22~28℃时,使用新制备的去离子水采用回旋振荡方式对土壤样品振荡浸取10min,经高速冷冻离心机离心使固液完全分离,从而建立了电感耦合等离子体原子发射光谱法(ICP-AES)直接测定土壤中水溶性硫酸根的分析方法。在选定的测定条件下,硫酸根的质量浓度在0.1~500μg /mL范围内与其对应的发射强度呈线性关系,校准曲线的线性相关系数r=0.9999。方法的检出限为0.26μg/g。按照实验方法测定土壤有效态一级标准物质GBW07412a、GBW07414a、GBW07415a、GBW07417a、GBW07459、GBW07461中水溶性硫酸根,结果与认定值的相对误差(RE)为-4.8%~4.4%,相对标准偏差(RSD,n=12)均不大于3.3%,满足中华人民共和国地质矿产行业标准土地质量地球化学评价规范DZ/T 0295—2016的分析质量要求。选择雄安新区酸性、碱性土壤样品和土壤有效态一级标准物质GBW07413a、GBW07415a、GBW07416a、GBW07417a,分别按照实验方法和NY/T 1121.18—2006滴定法、GB 8538—2016离子色谱法进行测定,结果无显著性差异。

Determination of water soluble sulfate in soil by inductively coupled plasma atomic emission spectrometry

The content of water soluble sulfate in soil is usually determined by EDTA titration method. However, it has some disadvantages such as complex operation and long analysis period. In order to adapt to analysis of samples in large quantities, the temperature, time and frequency for oscillation leaching were optimized. The soil samples were oscillated and leached by cyclotron oscillation for 10min using the freshly prepared deionized water at room temperature in range of 22-28℃. The solid and liquid could be completely separated through high speed freezing centrifuge. Consequently, a kind of method for the direct analysis method of water soluble sulfate in soil by inductively coupled plasma atomic emission spectrometry (ICP-AES) was established. Under the selected testing conditions, the mass concentration of sulfate in range of 0.1-500μg/mL had a linear relationship with the corresponding emission intensity, and the linear correlation coefficient of calibration curve was r=0.9999. The detection limit of method was 0.26μg/g. The content of water soluble sulfate in primary reference materials of available state of soil (including GBW07412a, GBW07414a, GBW07415a, GBW07417a, GBW07459 and GBW07461) was determined according to the experimental method. The relative errors (RE) between found results and certified values were between -4.8% and 4.4%, and the relative standard deviations (RSD, n=12) were all not more than 3.3%, which could meet the analysis quality requirements of Industrial Standard for Geology and Mineral of the People′s Republic of China (Specification of Land Quality Geochemical Assessment, DZ/T 0295-2016). The proposed method was applied for the determination of acid and alkaline soil samples from Xiong′an New Area as well as primary reference materials of available state of soil (GBW07413a, GBW07415a, GBW07416a and GBW07417a). Compared to titration method (NY/T 1121.18-2006) and ion chromatography (GB 8538-2016), the found results by experimental method had no significant difference.