Bromate determination in water using chlorpromazine after correction of chlorinating agents and humic substances interference

The presence of soluble humic substances and chlorinating agents interfered positively with the spectrophotometric determination of bromate (BrO ₃ ⁻ ) using chlorpromazine. Removal of the soluble humic substances through their precipitation by a basic lead acetate (15.9 g/L Pb(CH₃COO)₂ · 3H₂O-4.7 g/L PbO) solution corrected their interference effectively. In addition, the use of NaHSO₃ at pH 5.1 ± 0.2 eliminated the interference of ClO ₂ ⁻ , Cl₂-OCl⁻, and Cl₂-NH₂Cl, when present in concentrations of up to 1.5, 3.5, and 3.5 mg/L, respectively. Thus, the spectrophometric method was rendered suitable for the direct bromate determination in natural, chlorinated, and ozonated waters, since the application to such samples resulted in the accurate and precise determination of bromate. The method’s detection limit was estimated as 1.6 μg BrO ₃ ⁻ /L and the linear range of the calibration curve was extended up to 700 μg BrO ₃ ⁻ /L. The method also gave results comparable to those obtained by the well-established ion chromatographic method and had the additional advantage of being simple, rapid, low cost, and suitable for brackish water. The text was submitted by the author in English.