测定土壤硝态氮的紫外分光光度法和镉柱还原法比较

使用改进的紫外分光光度法(校正因素法)和基于镉柱还原的流动注射分析法(镉柱还原法)测定了中国10种不同类型土壤的NO3–-N含量,分析了两种方法的差异性及其适用性。统计分析表明,改进紫外分光光度法与镉柱还原法测定的结果具有极显著的相关性,测定样品的准确度介于89%~104%,具有可比性。在浓度适用上略有差异,对NO3–-N含量极低的土壤样品,采用镉柱还原法可提高精确度;对于NO3–-N含量高的土样选用紫外法可提高测定精确度,测定结果变异性低于镉柱还原法,且紫外法测定值都要高于镉柱还原法。从仪器操作及校准角度来看,紫外法测定操作过程简便,影响因子较少,对NO3–-N批量快速测定更为适用。

Comparison Between Ultraviolet Spectrophotometry and Cadmium Reduction Method in Determination of Soil Nitrate-N

The modified UV spectrophotometry and cadmium reduction method (flow injection analysis) are two main methods applied to rapid analysis of NO₃^- -N. To explore the difference and application in the measurement of NO₃^- -N by the two methods, 10 soil samples from different regions of China were determined by the two methods. Results showed that significant correlations existed between NO₃^- -N contents determined by the two methods, the precision of the two methods ranged from 89% to 104%. There are difference in methods application depend on the content range, for low content of NO₃^- -N, cadmium reduction method was better than UV spectrophotometry in accuracy, but for high content of NO₃^- -N, UV spectrophotometry was better with higher precision and lower variability, and the measured value using UV spectrophotometry method were higher than that using cadmium reduction method. UV spectrophotometry was more suitable for rapid analysis of large batches of soil samples for its simple operation and less interference factors.