SCREENING METHOD FOR THE GAS-CHROMATOGRAPHIC MASS-SPECTROMETRIC DETERMINATION OF MICROGRAM LITRE LEVELS OF BROMATE IN BOTTLED WATER/

Bromate can be formed as a by-product of ozone treatment that is somet imes used for the disinfection of municipal water supplies and bottled waters. The US Environmental Protection Agency has proposed a maximum contaminant level (MCL) of 10 mu g/l for bromate in public drinking w ater. Should the proposed MCL for bromate become final, it may then be considered for adoption as a bottled water quality standard by the US Food and Drug Administration. This paper reports the development of a gas chromatographic/mass spectrometric (GC/MS) method for the determi nation of parts-per-billion (mu g/l) levels of bromate (BrO3-) in bott led water. The GC/MS method was validated by using distilled and deion ized Milli-Q(R) water; detection limits, quantitation limits, and reco veries were determined and identities were confirmed by MS on the basi s of analyses of test portions fortified with BrO3- at 0.8, 3.8, 7.7, 1.5, and 46 mu g/l. The method also was evaluated on the basis of reco veries determined for two commercial brands of bottled water fortified with BrO at 3.8 and 7.7 mu g/l and two commercial brands fortified at 0.8, 3.8, and 7.7 mu g/l. For the Milli-Q(R) water, recoveries ranged from 100 to 121%; for the fortified commercial products, recoveries r anged from 87 to 115%. The limits of detection and quantitation were d etermined to be 0.4 and 0.7 mu g/l, respectively. Several commerical b rands of bottled water were analysed, and BrO3- was found in these pro ducts at levels ranging from none to 38 mu g/l.