凯氏定氮法测定土壤中水解性氮样品处理条件的三维响应曲面优化  

Optimization of sample pretreatment conditions with three-dimensional response surface methodology for determination of hydrolytic nitrogen content in soil by kjeldahl's azotometer

作　　者：马怡飞 柯艳 康文贵 李婧 王贝 MA Yifei;KE Yan;KANG Wengui;LI Jing;WANG Bei(Xi’an Northwest Geological Institute for Nonferrous Metals Co.,Ltd.,Xi’an 710054,China)

机构地区：[1]西安西北有色地质研究院有限公司,西安710054

出　　处：《化学分析计量》2018年第5期68-71,共4页Chemical Analysis And Meterage

摘　　要：利用三维响应曲面法优化LY/T 1228—2015测定土壤中水解性氮含量的实验条件。为了缩短反应时间,提高检测效率,使用三维响应曲面法对碱解蒸馏法的蒸馏条件进行优化,并据此建立凯氏定氮仪直接测定土壤中水解性氮含量的方法,优化后的实验条件:NaOH溶液的浓度为2.7 mol/L,蒸汽比率为100%,蒸馏时间为5 min。测定结果的相对标准偏差为1.76%～2.64%(n=5),优于碱解扩散法(2.66%～3.61%)。对3个国家一级标准物质进行测定,测定结果与推荐值相符。与标准方法相比,该方法成本低,可操作性强,特别适用于土壤环境质量评价、地区土壤抽样调查等大批量土壤样品分析。The conditions for determining hydrolytic nitrogen content in soil by LY/T 1228–2015 was opimized by three-dimensional response surface methodology.In order to shorten the reaction time and improve detection efficiency,the distillation conditions of alkali distillation method were optimized by using three-dimensional response surface methodology,and the method for determination of hydrolytic nitrogen content in soil by kjeldahl’s azotometer was established.The optimized experimental conditions:the concentration of NaOH solution was 2.7 mol/L,the steam ratio was 100%and the distillation time was 5 min.The relative standard deviation of the detection results was 1.76%– 2.64%(n=5),which was better than that by the method of alkali diffusion(2.66%–3.61%).Three certified reference materials were used to evaluate this method,the results were in confirming with the recomnended value.This method is low in cost and more operable than the standard method,and it is especially suitable for soil environmental quality assessment,regional soil sampling,etc.large quantities of soil sample analysis.

关 键 词：全自动凯氏定氮仪 土壤 水解性氮 三维响应曲面 

分 类 号：O655[理学—分析化学]