比色法测定土壤有机碳含量的可行性研究

研究了利用Cr[Ⅲ]比色法测定土壤有机碳含量的最佳波长、干扰因子和可靠性。结果表明：比色法最佳测定波长为585nm,不宜使用570nm以下通透滤光片;氯离子的干扰强度与滴定法相同,硫酸浓度对测定结果无显著影响。与滴定法相比,比色法测定无新增干扰因子,结果不受重铬酸钾加入误差的影响,用于土壤有机碳常规分析,可减少人为误差,提高测试精度和劳动效率,以葡萄糖为标准物质的综合消煮率宜以97％计算。相关信息还可为便携式速测仪和在线分析仪的开发设计提供数据参考。

The Feasibility of Determination of Soil Organic Carbon Content by Colorimetry

The optimum wavelenth, reliability and interfere factors of spectrophotometry method for determination of soil organic carbon content by trivalent chromic concentration were studied. The results showed that the highest sensitivity wavelenth used for Cr [ Ⅲ ] was 585 nm, less then 570 nm transparent filter will cause unexpected errors. Chloric anion did not cause more bias then titration method, the amount of concentrated sulfate acid added did not affect the measurement in common range. Compared to titration method, spectrophotometry elimited most of the artificial errors such as inacuracy addition of potassium dichromate, so there was no new error terms. The recovery rate of organic carbon was 97% in case of glucose calibrated. The method could be used in routine analysis of organic carbon with labor efficience and also benefit the application of portable equipments for field conditions and online monitoring.