Simultaneous determination of chloride and pH in wastewaters by sequential injection analysis

Abstract

A sequential flow-injection method for the simultaneous determination of pH and chloride ion in wastewaters using potentiometric detection is proposed. The method uses a separate flow cell to measure pH by stopping the flow during the determination of chloride. The ionic strength for the determination of chloride is adjusted by mixing an ionic strength adjuster (ISA) buffer solution with the sample on its way to the detector. pH measurements require no sample dilution. The proposed method was applied to wastewater samples and its performance compared with that of batch potentiometric procedures; no significative differences were found. Relative standard deviation of 1.0 and 1.2% for Cl− and pH, respectively, were obtained for 20 consecutive injections of 50 ppm Cl− standard solution and pH 4 buffer solution. © 1996 John Wiley & Sons, Inc.