镉柱还原法测定海水总氮方法的优化及改进  

Optimization of cadmium column reduction method for determination of total nitrogen in seawater

作　　者：时文博[1] 王娟娟[1] 王秀芹[1] 王德兴[1] 王宝峰[1] 

机构地区：[1]农业部渔业环境及水产品质量监督检验测试中心(天津),天津300221

出　　处：《河北渔业》2017年第7期47-50,共4页

摘　　要：本文对海水总氮测定方法进行了优化和改进,进行了锌镉还原和镉柱还原的还原率比较研究,确定了缓冲液的pH值,进行了镉柱还原样品间弃去液问题的研究。本方法采用过硫酸钾氧化,镉柱还原后加入磺胺溶液,再加入盐酸奈乙二胺溶液混匀,于543nm波长下测定。方法绘制的标准曲线线性为y=0.738 6x-0.016 6,相关系数r^2>0.99。空白加标测定回收率93.28%~104.93%,相对标准偏差3.87%。方法的精密度和准确度均较好,解决了原方法中标准曲线线性不稳定、还原率较低、测量结果误差较大的问题。The method for determination of total nitrogen in seawater was optimized. The reduction rate was compared between zinc -cadmium reduction method and cadmium column reduction method. In cadmium column reduction method,the pH value of buffer solution was determined, and the optimum amount of waste liquid among samples was studied. In this method, after potassium persulfate oxida-tion and cadmium column reduction, sulfadiazine solution was added to the sample, and then hydro-chloric acid ethylenediamine solution was added. After mixed evenly, absorbance of the sample solu-tion was measured at 543 nm, and the standard curve linear was y = 0. 738 6x-0. 016 6, with the cor-relation coefficient r2 〉0. 99. The standard addition recovery was between 93. 28%^-104. 93%, and the relative standard deviation was 3. 87%. The precision and accuracy of the method are good, which solved some problems that exist in the original method such as the unstable standard curve, low re-duction rate and relatively big measurement error.

关 键 词：镉柱还原法 总氮 优化 

分 类 号：P714.4[天文地球—海洋科学]