DEVELOPMENT OF INDICATOR FOR ON-SITE DETECTION OF BROMATE IN SOME BREAD SAMPLES IN ABEOKUTA METROPOLIS

Abstract

A new highly selective indicator, Chitosan-Silver Carmoisine (CTS-AgCAM) was developed for the detection of potassium bromate in bread. The detection was based on the oxidation of Carmoisine (CAM) by potassium bromate (KBrO3), catalysed by Silver Nanoparticles (AgNPs). The CTS-AgNPs was prepared by the reaction of silver nitrate with sodium hydroxide and stabilised in chitosan (CTS) and further addition of CAM. Batch experiments were carried out on various concentration of KBrO3 to obtain optimal conditions for the use of the indicator. This was monitored with a UV-Vis Spectrophotometer. Fifty bread samples were then collected randomly from five different bakeries within Abeokuta, Ogun state, Nigeria and qualitative analysis was carried out on the bread samples using the prepared indicator. The UV-Vis spectrum of the CTS- AgNPs revealed surface plasmon absorption maxima at 418-420 nm while the indicator showed maximum absorption at 516 nm. From the qualitative analysis, it was observed that on addition of 2 drops of CTS-AgCAM to a bread sample solution containing KBrO3, a pink colour of the indicator disappeared. It was also observed from the result of quantitative analysis that the fifty bread samples analyzed all containedKBrO3with concentration ranging between 3.23 ± 0.08 and 6.29 ± 0.91 µg/g. The indicator worked best between 1 and 5 µg/g and had a detection limit of 1 µg/g. The result showed that this indicator can be used easily for efficient on-site detection of bromate in bread.