泥沙对总氮测定结果的干扰影响分析

The Impact of Sediment Content on the Determination of Total Nitrogen

分析了泥沙含量对总氮测定结果的干扰影响,结果表明:水样中泥沙的含量与其对水样总氮的贡献有显著的正相关性;泥沙对总氮测定结果有干扰影响,随泥沙含量增加,A275的测定值及总氮降低率逐渐增大,且当泥沙(SS)含量≥45 mg/L时,其A275/A220的值在20%以上,总氮降低率在15%以上,从而总氮测定值产生较大的误差。消解后离心法或消解后0.45μm滤膜过滤法能有效地消除泥沙的干扰,并均具有操作简单和准确度高的优点。

The impact of sediment content on the determination of total nitrogen was investigated. The results indicated that a significantly positive relationship between the amount of sediment content and its contribution to total nitrogen content in water sample was found, and sediment content had significant interference effect on the determination of total nitrogen. The value of A275 and the reduction rate of total nitrogen increased gradually with the amount of sediment content elevation. When the concentration of sediment content （ss） was greater than 45 mg/L, the ratio of A275 to A220 was above 20% and the reduction rate of total nitrogen was above 15%, which produ-ced greater error in the determination of total nitrogen. The centrifugation after digestion or the filtration by 0.45 μm after digestion could effectively eliminate the interference of sediment content. Two methods had the advantages of simple operation and high accuracy.