振荡交换—蒸馏滴定法测定土壤中阳离子交换量

Determination of Cation Exchange in Soil by OscillatoryExchange-Distillation Titration Method

测定土壤阳离子交换量常用的标准方法是采用手工搅拌离心分离结合手工蒸馏进行滴定,操作繁琐,耗时长。为提高检测效率,缩短流程时间,通过EDTA-乙酸铵对酸性和中性土壤及氯化铵-EDTA-乙酸铵对石灰性土壤进行处理,采用振荡交换离心和蒸馏硼酸吸收盐酸滴定计算CEC值。结果表明,对振荡时间及离心次数的实验条件优化,在最佳实验条件下,一个批次样品(60件)分析流程需要9 h,比传统方法检测时间缩短近60%。经国家标准物质验证,该方法的精密度和准确度均符合要求。其操作性较强、效率高,适用于大批量土壤样品的测定。

The commonly used standard method for the determination of soilcation exchange capacity(CEC)is to titrate by hand stirring centrifugal separation combined with hand distillation,which is complicated and time-consuming.In order to improve the detection efficiency and shorten the process time,this paper treated acidic and neutral soil with EDTA-ammonium acetate,treated calcarous soil with ammonium chloride ed TA-ammonium acetate,and titrated with hydrochloric acid absorbed by boric acid by oscillation exchange centrifugation and distillation,thereby calculating CEC value.The results show that under the experimental conditions such as the oscillation time and the number of centrifuges,the analysis process of one batch of samples(60 pieces/person)takes 14 h,which is nearly 50%shorter than the traditional method.The precision and accuracy of the method meet the requirement after verification by the national standard material.This method has strong operability and high efficiency,and is suitable for the determination of large quantities of soil samples.