Determination of bromate in bread by capillary gas chromatography with a mass detector (GC/MS)

Abstract

A sensitive method was developed for the determination of bromate in bread by capillary gas chromatography with a mass detector (GC/MS). Bromate was extracted with water from bread samples. After centrifugation, the supernatant was filtered and Cl- was removed by an OnGuard-Ag cartridge column. The mixture was absorbed on a DEA solid phase extraction column and washed with water. Bromate was then eluted with 3 M potassium chloride solution. Two ml of 4 x 10(-3) M styrene monomer solution (washed with 1% sodium hydroxide solution before use), 1 ml 0.01 M potassium bromide solution and 1 ml sulphuric acid were added to the eluent and shaken vigorously. The styrene bromo derivative (alpha-bromomethyl-benzenemethanol[2-bromo-1-phenylethanol]) was extracted with 2 ml n-hexane, and determined by GC/MS. Recoveries of bromate from breads were in the range 91.3-98.1% (0.03-0.50 micrograms/g), and the limit of detection was 0.03 microgram/g. Pullman and open top types of white bread, produced by a sponge and dough method and a short process method respectively, were prepared in our laboratory for measurement of residual bromate. When 30 micrograms/g or less bromate as HBrO3 (pullman type), and 75 micrograms/g bromate or less as KBrO3 (open top type), was added to flour, no residual bromate was detected in either type of bread.