微波消解一纳氏试剂分光光度法测定土壤中总氮

采用微波消解对土壤样品中的氮进行前处理，用纳氏试剂分光光度法测定总氮，发现微波消解最佳条件为：用2mL浓H2S0。和1mLHF，于0．2Mpa下保持3rain，0．5MPa下保持2min，0．7MPa下保持5rain；方法的检出限为0．0034mg／L，相对标准偏差RSD为6．7％，加标回收率为85．90％～114．5％，与半微量凯氏定氮法比较的相对误差为-1．16％。说明微波消解法消化土壤样品测定总氮，具有简便、快速、精密度与准确度较高等优点。

Spectrophotometric Determination of Total Nitrogen in Soil with Nessler＇ s Reagent Coupled with Microwave Digestion

The nitrogen species in soil is pre-treated with microwave digestion, followed by determination of the total nitrogen with spectrophotometry coupled with Nessler＇ s Reagent. The result indicates that the optimal experimental conditions are as follows： 2 ml concentrated H2SO4 ＆lmlHF with the constant 3 min in 0.3 MPa and constant 2 rain in 0.5 Mpa and 5min in 0.7 MPa. The method,with 0. 003 4 mg/L of detection limit and 6.7% of relative standard deviation and 85.90% -114.5% of recovery of standard addition and - 1.16% of relative error compared with National Standard, is available to determination of total nitrogen in soil due to its simplicity, quickness,better precision ＆ accuracy.