磁力搅拌法改进土壤阳离子交换量测定的研究

针对传统土壤阳离子交换量测定方法中的玻璃棒搅拌所存在的分析效率低的问题,开展了运用磁力搅拌替代玻璃棒搅拌的探索性研究。通过平行性实验、条件实验、实验室间对比和不同黏粒含量土壤的CEC测定结果检验,分析了磁力搅拌法的精准度、可操作性、稳定性和适用性。结果表明,磁力搅拌法测定土壤CEC的准确度、精密度均不低于甚至高于玻璃棒搅拌方法,土壤CEC测定值与土壤标准物质认定值吻合。当搅拌时间在1 min、搅拌速度850 r·min^–1以上时,延长搅拌时间和提高搅拌速度对分析结果无影响。不同实验室间测定结果相关性好、没有显著性差异。相比传统的玻璃搅拌法,磁力搅拌法具有操作简单、高效,测定结果稳定性好、精准度高等优点,非常适用于大批量土壤CEC的测定。

Study on Improving Soil CEC Determination by Magnetic Stirring Method

In order to resolve the problem of low efficiency of the measurement of soil cation exchangeable capacity(CEC)with the traditional glass rod stirring method,an experiment was designed to stir suspensions with a magnetic stirrer instead of glass rod.Parallel tests different in controlled condition were carried out in different labs to determine CEC of soils different in clay content with the magnetic stirring method for comparison between the tests in accuracy,operability,stability and applicability of the measurements with the method.Results show that the magnetic stirring method was not lower or even magnetic stirring method higher than the glass rod stirring method in accuracy and precision of the CEC measurement.What was obtained with the former was highly in consistency with the values of the certified reference materials.When stirring of the suspension went on over 1 min at no less than 850 r·min-1,duration and speed of the stirring did not have much effect on soil CEC determination,and neither the labs where the tests were conducted.No significant difference was found between labs in CEC measurement.Compared with the traditional glass rod stirring method,the magnetic stirring method has such merits as simple in operation and high in efficiency,stability and precision,when used to measure soil CEC,and is highly suitable for use to determine soil CEC of large batches of soil samples.