连续流动法测定土壤中有机质

Determination of organic matter in soil by continuous flow analysis

建立连续流动化学分析法测定土壤中有机质含量。采用自动凯氏消化器对样品进行加热,使有机质在硫酸作用下被重铬酸钾氧化成二氧化碳和水,过量的重铬酸钾在酸性条件下,与1,5-二苯基碳酰二肼反应生成紫红色络合物,用连续流动化学分析仪测定。该法线性范围为0.4~2.0 g/L,线性相关系数为0.999 0,测定结果的相对标准偏差为0.48%~2.85%(n=6),土壤标准物质测定值与标准值吻合。该法与NY/T 1121.6—2006方法对土壤中有机质的测定结果无显著性差异。

A method was established for the determination of organic matter in soil by continuous flow analyzer.KJELDAHL digester was used for heating the sample,the organic matter in sample was transformed to carbon dioxide and water after oxidized by potassium dichromate oxidizes under the action of sulfuric acid,and the excess potassium dichromate reacted with 1,5-diphenylcarbazide to form a purplish red complex,which would be determined by continuous flow analyzer.The correlation coefficient was 0.9990 with the linear rang of organic matter content from 0.4 g/L to 2.0 g/L.The relative standard deviation was 0.48%-2.85%(n=6),and the detection value of the reference material of soil matched the standard value.The detection results had no significant difference between the method and standard method of NY/T 1121.6—2006 in the determination of soil organic matter.