Studies on analytical methods for determination of potassium bromate in foods

Abstract

A high performance liquid chromatographic (HPLC) method for the determination of bromate in bread and flour has been developed. Bromate was extracted from samples with water. The extract was cleaned by the use of a LiChrolut SAX cartridge (perchlorate form) with 0.06 M sodium perchlorate solution (pH 3.5) as a fluent. Bromate was separated with Zorbax SAX column by using 0.06 M sodium perchlorate solution (pH 3.5) the mobile phase, and detected at 355 nm after derivatization in the post column 80°C. Recovery studies were performed using bread and flour samples each fortified with bromate at 0.2, 0.5 and 1 μg/ml separately. Recoveries were in the range of 80.0-86.1% with coefficients of variation under 1.9%. The limit of detection was 0.1 ppm. For purposes of comparison, a study on high performance ion chromatography for the determination of bromate in flour was performed. Sample solution was prepared in the same way as in HPLC method, except that the sample was passed through an OnGuard-Ag cartridge instead of a LiChrolut SAX cartridge to remove chloride. Bromate was analyzed with Dionex HPIC AS11 and AG11 column by using 0.25 mM sodium hydroxide solution as an eluent, in combination with a conductivity detector. Recovery studies were performed using flour samples fortified with bromate at 1, 2 and 5 μ g/ml. Recoveries were in the range of 79.7-86.3% with coefficients of variation under 3.9%. The limit of detection was 0.5 ppm. Forty bread and ten flour samples collected from various markets were analyzed. No bromate residue was detected in any samples tested.