地下水中硅酸浓度测定方法的研究

Study on determination method of silicic acid concentration in groundwater

目的:通过实验和数据分析,提高地下水分析方法(DZ/T0064.62-2021)中硅酸含量的测定上限,为实际测试工作提供更加有效、便捷的实验条件,解决地下水测定中遇到的一些实际问题。方法:在pH值为1~2的酸性溶液中,钼酸铵与水中可溶性硅酸反应,生成黄色的硅钼酸络合物,显色20分钟后,在440 nm测定吸光度,在一定浓度范围内,其吸光度与可溶性硅酸浓度成正比。结果:地下水中硅酸浓度在50微克-2500微克之间线性良好,相关系数r=0.9997,检出限为0.1 mg/L;测定上限为65.68 mg/L;已知含量样品的相对标准偏差分别为2.29%、5.77%和3.53%;加标回收率范围为:95.92%~106.80%。结论:该方法的测定上限可以达到65.68 mg/L,在水质分析测试中,具有很强的实际意义。

Objective:Through experiments and data analysis,to improve the upper limit of the determination of silicic acid content in groundwater analysis method(DZ/T0064.62-2021),provide more effective and convenient experimental conditions for the actual test work,and solve some practical problems encountered in groundwater determination.Methods:In the acidic solution with pH value of 1~2,ammonium molybdate reacts with soluble silicic acid in water to form yellow Silicomolybdic Acid complex.After 20 minutes of color development,the absorbance is measured at 440 nm.Within a certain concentration range,the absorbance is directly proportional to the concentration of soluble silicic acid.Results:The concentration of silicic acid in groundwater ranged from 50μg to 2500μg,with good linearity,correlation coefficient r=0.9997 and detection limit of 0.1 mg/L;The upper limit of determination is 65.68 mg/L;The relative standard deviations of known samples were 2.29%,5.77%and 3.53%,respectively;The recovery range of standard addition is 95.92%~106.80%.Conclusion:The upper limit of this method can reach 65.68 mg/L,which has strong practical significance in water quality analysis and testing.