Quantitative analysis of bromate in non-alcoholic beer using ultra performance liquid chromatography-electrospray ionization mass spectrometry

Abstract

Bromate (BrO₃⁻) is a possible human carcinogen which is formed as a bromide containing source water ozone disinfection by-product. Thus, BrO₃⁻ is subject to assess its threat to humans. In the present study, an ultra performance liquid chromatography-electrospray ionization mass spectrometry method has been developed for the quantitative analysis of BrO₃⁻ in non-alcoholic beer. The chromatographic separation of both transitions ⁸¹BrO₃⁻ and ⁷⁹BrO₃⁻ (isotope contributions of ⁷⁹Br and ⁸¹Br) was carried out and achieved in <1 min, with superior peak symmetry. The good quality parameters were obtained such as linearity (R² > 0.9999), precision (repeatability and reproducibility in terms of relative standard deviation) <1% at 1.0 μg mL⁻¹ standard and <3% in the analysis of sample 1 (classic malt) and sensitivity with a low limit of detection (LOD, ⁸¹BrO₃⁻, 0.03 ng mL⁻¹ and ⁷⁹BrO₃⁻, 0.03 ng mL⁻¹) and limit of quantification (LOQ, ⁸¹BrO₃⁻, 0.1 ng mL⁻¹ and ⁷⁹BrO₃⁻, 0.1 ng mL⁻¹) in the standard. Nevertheless, the LOD and LOQ in sample 1 (classic malt) were obtained only for transition ⁸¹BrO₃⁻, 0.05 ng mL⁻¹ and 0.16 ng mL⁻¹, respectively. For transition ⁷⁹BrO₃⁻ the obtained peak was below the limit of detection. A total of 39 non-alcoholic beer samples of different flavors were analyzed and the ⁸¹BrO₃⁻ level in classic samples was found between 1.20 μg mL⁻¹ and 3.73 μg mL⁻¹, however, in other flavored samples the concentration levels reached up to 14.04 μg mL⁻¹ with excellent recovery rates (96–99%). In most of the analyzed real samples, only transition ⁸¹BrO₃⁻ was found nevertheless, transition ⁷⁹BrO₃⁻ was either <LOD or completely diminished from the obtained sample chromatogram. This is one of the main findings from the present study and the mechanism of this cause is unknown. The obtained BrO₃⁻ levels were much higher than the limits in drinking water (10–25 ng mL⁻¹) recommended by several regulatory agencies.