FLUOROMETRIC-DETERMINATION OF BROMATE BY ION-EXCHANGE SEPARATION AND POSTCOLUMN DERIVATIZATION

For the determination of bromate in drinking water a stopped-flow post -column reaction was developed following the separation of bromate fro m the matrix by an anion-exchange column. Tn the postcolumn reaction t he analyte was used to oxidize the azo dye sulfonaphtholazoresorcinol, SNAR, and the residual amount was converted into a fluorescent binucl ear complex by an excess of gallium ions. The fluorescence was monitor ed at 585 nm, with a maximum excitation wavelength at 521 nm. The dete rmination of bromate is based on the decrease of the fluorescence. int ensity with increasing bromate concentration. The given hydrodynamic p arameters and the condition of equal flow rates of the two branch stre ams at each T-piece have to be considered as an important criterion fo r the experimental set-up. The volume flows and the concentrations req uired for the reagent solutions in the influent of each T-piece were d etermined as a result of batch experiments and theoretical considerati ons. The limit of detection was 0.28 mu g L-1 bromate for the flow met hod, which shows linearity up to 15 mu g L-1 bromate.