SIMULTANEOUS DETERMINATION OF CHLORIDE AND PH IN WASTEWATERS BY SEQUENTIAL INJECTION-ANALYSIS

A sequential flow-injection method for the simultaneous determination of pH and chloride ion in wastewaters using potentiometric detection i s proposed. The method uses a separate flow cell to measure pH by stop ping the flow during the determination of chloride. The ionic strength for the determination of chloride is adjusted by mixing an ionic stre ngth adjuster (ISA) buffer solution with the sample on its way to She detector. pH measurements require no sample dilution. The proposed met hod was applied 50 wastewater samples and its performance compared wit h that of batch potentiometric procedures; no significative difference s were found. Relative standard deviation of 1.0 and 2.2% for Cl- and pH, respectively, were obtained for 20 consecutive injections of 50 pp m Cl- standard solution and pH 4 buffer solution. (C) 1996 John Wiley & Sons, Inc.