连续流动注射分析法测定总氮研究

Determination of Total Nitrogen by Continuous Flow Injection Analysis

通过连续流动注射分析仪进行试验,检验水中总氮指标,检测的水样和试剂混合后,经紫外与110℃高温消化后,再经过镉的还原,水样中的硝酸盐氮被还原成亚硝酸盐氮,亚硝酸盐氮与显色剂反应生成紫红色化合物,在540 nm波长处量定吸光度。根据测定结果分析仪器方法的标准曲线相关系数、分析仪器方法检出限、精密度和准确度。结果表明,连续流动注射分析法测定总氮的标准曲线在0.00~10.00 mg/L标准溶液浓度系列之间线性相关系数能达到0.99997,线性关系较好。连续流动注射分析法测定总氮方法检出限0.022 mg/L,标准方法检出限为0.04 mg/L,连续流动注射分析法测定总氮精密度在0.60%~1.86%,标准方法要求精密度小于5%,连续流动注射分析法测定总氮的方法检出限和精密度均明显优于标准方法,且低、中、高3个不同浓度值的总氮样品加标回收率在96.7%~106%,标准物质测定相对误差为2.26%,较为理想,连续流动注射分析法准确度较高。连续流动注射分析法能够满足常规水体总氮的检测要求,能够满足普通水体中总氮含量的检测。

By continuous flow injection analyzer,the total nitrogen index in the water was tested.After the water sample and reagent were mixed,digested by UV and 110℃,the nitrate nitrogen in the water sample was reduced to nitrite nitrogen.The nitrite nitrogen reacted with the chromogen to produce purple red compound,measuring fixed absorbance at the wavelength of 540 nm.The standard curve correlation coefficient,detection limit,precision and accuracy were analyzed according to the measurement results.The standard curve correlation coefficient,detection limit,precision and accuracy of analytical instrument method were analyzed according to the measurement results.The results showed that the linear correlation coefficient of the standard curve for the determination of total nitrogen was 0.99997 between the concentration of 0.00 mg/L and 10.00 mg/L standard solution.The detection limit of total nitrogen determined by continuous flow injection method is 0.022 mg/L,while that of the standard method is 0.04 mg/L.The precision of total nitrogen determined by continuous flow injection method is between 0.60%and 1.86%,while that of the standard method is less than 5%.The detection limit and precision of the continuous flow injection method for the determination of total nitrogen are obviously better than the standard method,and the spiked recoveries of total nitrogen samples with low,medium and high concentration values are between 96.7%and 106%,and the relative error of standard matter determination is 2.26%,which is relatively ideal,and the accuracy of continuous flow injection method is high.Continuous flow injection analysis method can meet the requirements of the detection of total nitrogen in conventional water and can meet the detection of total nitrogen content in ordinary water.