Water Quality Determination by Electrically Controlled DPD Spectrophotometry Method Research

Abstract

This article points out that free residual chlorine and monochloramine are important water quality indicators for measuring disinfection effects in various water industries.For the "Standard Inspection Method for Drinking Water Standard Test Method Disinfectant Index GB/T 5750.11-2006", the N,N-diethyl-p- pheny lenedi amine (DPD) spectrophotometric method for the determination of free residual chlorine and monochlorine in drinking water and its source water Amine for method validation. The results showed that: the correlation coefficient of the free residual chlorine determination standard song is 0.9994; the detection limit is 0.01mg/L, the lower limit of determination is 0.04 mg/L, and the detection limit meets the requirements of the method; the content levels are 0.73mg/L, 3.2mg/L, The free residual chlorine content of the L residual chlorine sample was measured in parallel for 6 times, the relative standard deviations were 3.5% and 2.9% respectively, and the precision met the method requirements; the free residual chlorine content level of the actual water sample was 0.05mg/L, 0.4mg/L, 1.0mg/L spiked experiment was measured 6 times, the average recovery rate of free residual chlorine: 104%, 103%, 97.1%, the accuracy meets the requirements of the method. For the content level of 0.11mg/L and 1.2mg/L residual chlorine samples, the monochloramine content was measured in parallel for 6 times to determine the precision. The relative standard deviations are respectively: 0~5.6%, 0.34~4.0%, and the precision meets the requirements of the method. Therefore, it is confirmed that this method is applicable and feasible in this laboratory for the determination of free residual chlorine and monochloramine in water quality.