Simple and rapid determination of trace bromate by flow injection analysis with novel spec trophotometric detection system

A flow injection system with a novel detection reaction is presented for determining trace bromate in drinking water. Bromate is used to oxidize V(IV) to V(V), and then Nitro-PAPS 12-(5Nitro-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino] phenol) reacts with V(V) to form a complex that is monitored spectrophotometricaly at 592 nm in a continuous flow system. The variables related to such reactions were studied in detail, and the optimal conditions and manifold configurations were established. A linear calibration using a 2 m sample loop injection was obtained for bromate in the range of 0 similar to 0.05 ppm. The coefficient of variation for 0.01 ppm bromate (n = 3) was 0.6%, and the estimated limit of detection (3 sigma) was 0.0004 ppm. Only 4 min was required for an analytical measurement after sample injection. The present FI system was successfully in-line coupled with anion-exchange separation using 0.05 M NaCl as an eluent for a more sensitive and selective determination of trace bromate. In this case, using a 3 m sample loop, the limit of detection (3 a) was 0.0002 ppm bromate, the rsd for 0.01 ppm bromate was 1.4% and the time required for an analytical measurement was 9 min. Tap water samples supplied from 3 cities and a bottled water were analysed by this FI system; satisfactory recoveries of 96 similar to 104% were found for spiked bromate.