DPD分光光度法测定循环冷却水中余氯的探讨

Determination of residual chlorine in the cycle by water DPD spectrophotometric method

针对以N,N-二乙基对苯二胺分光光度法测定循环冷却水中余氯出现的问题进行了实验研究.考察了样品保存方法、pH值、掩蔽剂、显色反应时间等,结果表明：样品保存时,应将pH值控制在11～12、样品测定时,pH值控制在6.2～6.5、在缓冲溶液中加入EDTA掩蔽剂、试剂与试样加入顺序应先用缓冲溶液调节,DPD试剂溶液pH值在6.2～6.5,然后边搅拌边加入试样、显色反应10min,当标准溶液中余氯含量不大于0.900mg·L-1时,回归方程的相关系数为0.998、相对标准偏差为4.6％,测定结果与装置投放杀菌剂的总量吻合.

The residual chlorine in the cycle water was determined by DPD spectrophotometric method. The conservation of sample, pH value, masking agent and chromogenic reaction time were investigated. The results showed that the pH value should be 11-12 when sample conservation, 6.2-6.5 when sample determination, adding EDTA masking agent to buffer solution, the order of reagent and sample is added to the buffer solution to adjust the pH value of DPD between 6.2-6.5, then adding sample with stirring, color reaction for 10 minutes. When residual chlorine in standard solution is less than 0.900mg· L^-1, the correlation coefficient of regression equation is 0.998, the relative standard deviation is 4.6%, determination result matched antiseptic in device.