土壤颗粒粒径及进样量对TOC含量测定精度的影响

Effects of soil particle size and sample size on the determination accuracy of TOC content

为了准确高效地测定土壤有机碳(TOC)含量,研究了土壤颗粒粒径及进样量对TOC分析仪测定土壤TOC含量的影响,并比较了TOC分析仪法与重铬酸钾外加热法-沸水浴测定TOC含量的差异。结果表明:过60目筛的颗粒进样量在175—275 mg,所测TOC含量与过100目筛的颗粒无显著差异,TOC含量的变异系数(CV)<3%,加标回收率在98%—102%,检测结果的精密度及准确性良好。酸性土壤的无机碳(IC)为0,总碳(TC)=TOC; TOC分析仪与重铬酸钾外加热法-沸水浴的测定结果无显著差异,两者相关性良好。TOC分析仪对有机碳含量高、中、低样品的检测结果准确稳定,重铬酸钾外加热法-沸水浴测定TOC含量> 15 mg g样品的准确性与TOC分析仪法相当,测定TOC含量5—15 mg g样品的准确性有所下降。

In order to determine the soil TOC （Total organic carbon）content accurately and efficiently, the effects of soil particle size and sample size on soil TOC content determined by TOC analyzer were studied, and the difference of soil TOC content determination between TOC analyzer method and potassium dichromate external heating method-boiling water bath was compared and analyzed. The results showed that the sample size passing through 60-mesh sieve was 175-275 mg, and there was no significant difference between the TOC content measured by 60-mesh sieve and that of 100-mesh sieve. The coefficient of variation （CV） of TOC content was less than 3% ,and the recovery rate was 98% 102%. The precision and accuracy of the test results were good. There was no significant difference between the resuhs measured by TOC analyzer and potassium dichromate external heating method-boiling water bath, and the correlation between them was good. TOC analyzer was accurate and stable for measurement of TOC content in high, medium and low content. The accuracy of potassium dichromate external heating method-boiling water bath method for the determination of TOC content 〉 15 mg/g was similar to that of TOC analyzer. The determination accuracy of TOC content in 5-15 mg/g samples decreased.