氧化还原消化-全自动凯式定氮法测定水质中的总氮

Determination of Total Nitrogen in Water Quality by Redox Digestion-automatic Kjeldahl Method

本方法建立了氧化还原消化,全自动凯式定氮法测定水中的总氮。以氧化剂、还原剂、硫酸和加速剂加入量为因素,开展4因素3水平的消化剂用量正交实验,结果表明最佳消化剂用量为40 mg高锰酸钾,5 mL硫酸,0.5 g还原铁粉,2 g加速剂,并探讨方法的检出限、精密度、准确度和加标回收,结果表明:本方法检出限为0.051 mg/L,相对标准偏差为1.97%~3.06%,加标回收率为96.00%~102.44%,标准物质所测得结果均在不确定范围内。说明本法具有较好的精密度和较高的准确度,且操作简单,自动化程度高,能满足日常检测要求。

This method established REDOX digestion,automatic Kay nitrogen determination method for the determination of total nitrogen in water.The orthogonal experiment of digestible dosage with 4 factors and 3 levels was carried out with the amount of oxidant,reducing agent,sulfuric acid and accelerant added as factors.The results showed that the optimal digestible dosage was 40 mg potassium permanganate,5 mL sulfuric acid,0.5 g reduced iron powder and 2 g accelerant.The detection limit,precision,accuracy and standard recovery of the method were discussed.The detection limit of the method was 0.051 mg/L,the relative standard deviation was 1.97%~3.06%,and the recovery rate was 96.00%~102.44%.The results of the method were all in the uncertain range.This method has good precision and high accuracy,simple operation,high degree of automation,and can meet the requirements of daily detection.