COD_(Cr)测定中排除氯离子干扰的进一步探讨

废水中化学需氧量的测定采用重铬酸钾法［１］，大多数情况下都存在Ｃｌ－干扰，其排除方法用ＨｇＳＯ４掩蔽，通过实验探讨不用剧毒药品ＨｇＳＯ４掩蔽Ｃｌ－的干扰，而用ＣＯＤＣｒ总量减去Ｃｌ－的量。实验结果表明：当测定化学需氧量较低而Ｃｌ－含量高的水样时，即使采用掩蔽Ｃｌ－也会产生较大的误差，而用测定值减去０．２２６［Ｃｌ－］之值更接近真值。

Further discus about eliminating chlorine ion disturbance as determining COD Cr

Heavy potassium chromate method was adopted to determine COD Cr in sewage while there existed Cl disturbance in most cases that could be eliminated by HgSO 4 cover.Based on experiment,this article discussed the way of covering Cl disturbance by reducing the amount of Cl from that of total COD Cr ,without using strong poisonous HgSO 4.The experiment result showed that even Cl covering method could introduce obvious error while determining water sample with lower content of COD Cr and higher content of Cl ,however,the determined value minus the value of 0.226 were closer to ture value.