o-Dianisidine: a new reagent for selective spectrophotometric, flow injection determination of chlorine.
A flow injection analysis (FIA) procedure for the determination of free chlorine in industrial formulations and water samples is proposed. The manifold is provided with a gas-diffusion unit which permits the removal of interfering species and also the preconcentration of chlorine. The determination of chlorine is performed on the basis of the oxidation by o-dianisidine as a chromogenic reagent to a coloured product which can be monitored at 445 nm. The method (for a preconcentration step of 60 s) is linear over the range 0.04-1.00 mg l(-1) of chlorine, the limit of detection is 0.04 mg l(-1), the reproducibility of the procedure (as RSD of the slope) is 3.7% for a series of four independent calibrations, the precision (as RSD of a series of 30 continuous FIA peaks of 0.56 mg l(-1) of chlorine) is 1.4% and the sample throughput is 40 h(-1). A detailed comparative study of the analytical characteristics of a single mono-channel reverse FIA assembly and the same system but provided with a Fluoropore membrane filter of 0.5 microm pore size was performed to check the advantages of the new approach in terms of sensitivity, selectivity and limit of detection.
Catalá Icardo
M
M
Departamento de Química Analítica, Universidad de Valencia, Spain.
García Mateo
J V
JV
Martínez Calatayud
J
J
D002713:Chlorine / Q000032:analysis*; D002863:Chromogenic Compounds; D003962:Dianisidine; D017022:Flow Injection Analysis / Q000295:instrumentation / Q000379:methods; D013053:Spectrophotometry; D014874:Water Pollutants, Chemical / Q000032:analysis*
D002863:Chromogenic Compounds; D014874:Water Pollutants, Chemical; D002713:Chlorine; D003962:Dianisidine