Determination of bronopol and its degradation products by HPLC

Bronopol (2-bromo-2-nitropropane-1,3-diol) is widely used as an anti-microbial in cosmetics, external medicaments, shampoos and bath preparations. A reversed-phase high performance liquid chromatographic separation method with UV spectrophotometric detection was developed for the determination of bronopol and its degradation products. Degradation of bronopol was observed in aqueous medium, giving rise to non-reproducible data. To overcome this problem, HPLC grade methanol (water content <0.05%) was used for sample preparation. In addition, the parameters for the HPLC analysis of bronopol were optimised. It was found that bronopol standards and product samples were stable in methanol for at least 1 month at ambient temperature, thus allowing a quantitative and reproducible determination of bronopol.