重铬酸钾外加热法测定土壤有机质的不确定度评定

摘要

The uncertainty in determining soil organic matter by potassium dichromate heating method was evaluated, and the uncertainty sources in the whole determining process were analyzed in detail. The results showed that the four procedures, including adding 5 mL of potassium dichromate standard solution,titration procedure,repetitive titration and multiplying by the coefficient 1.1 ,had a comparatively high uncertainty,and so it was necessary to use a more accurate measuring device,decrease temperature difference in experiment and increase repetitive titration groups in order to improve the accuracy of measurement.%对重铬酸钾外加热法测定土壤有机质进行不确定度评定和对测量过程中的不确定度来源进行详细分析.结果表明:加入5 mL重铬酸钾标准溶液、滴定过程、重复滴定和乘以系数1.1等4个过程在有机质测定过程中引入不确定度比较高,因此在有机质测定过程中要通过更精密的量具、减少试验温差、增加测量试验的滴定重复组来提高土壤有机质测量的精度.