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应用离子色谱法代替凯氏消煮法(农业标准)测定土壤中的总氮,以改善测定的准确度、精密度和速度。样品经管式炉燃烧后,用含有H2O2的1%KOH溶液吸收,此吸收液经固相萃取柱净化后离子色谱测定。结果表明,在25μL进样量下,NO3-浓度在0.1～25.0 mg/L时,峰面积与浓度呈线性关系,相关系数为0.9996。测定3种不同地区的农田土壤,以检验其精密度和回收率,所得RSD值(n=5)在2.3%～3.1%之间,回收率为90.4%～100.6%。经检验,该测定结果与凯氏消煮法的结果之间差异不显著。
Determination of total nitrogen in soil by ion chromatography instead of Kjeldahl method (agricultural standard) to improve the accuracy, precision and speed of the assay. After the sample was burned in a tube furnace, the sample was absorbed with 1% KOH solution containing H2O2, and the absorption liquid was purified by solid-phase extraction column and determined by ion chromatography. The results showed that there was a linear relationship between peak area and concentration at a concentration of 0.1 ~ 25.0 mg / L with a mass concentration of 25 μL and a correlation coefficient of 0.9996. The precision and recovery of farmland soils in three different areas were determined. The obtained RSD values (n = 5) ranged from 2.3% to 3.1% and the recoveries ranged from 90.4% to 100.6%. After testing, the results of the determination and the Kjeldahl method no significant difference between the results.