Ultra trace determination of bromate in mineral water and table salt by liquid chromatography-tandem mass spectrometry.

A liquid chromatography-tandem mass spectrometry method (LC-MS/MS) was developed in order to determine the bromate in mineral water and table salt. The following optimum conditions for the LC-MS/MS detection were established: derivatization reagent (300 mg/L of 2,6-dimethylaniline), acidity (0.2M HCl), reaction temperature (30 °C) and heating time (20 min). The formed derivative was directly injected in the LC system without extraction or purification procedures. In the established conditions, the method was used to detect bromate in mineral water and table salt. The limit of detection and limit of quantification of bromate in mineral water were 0.02 μg/L and 0.07 μg/L, respectively, and those of table salt were 0.07 μg/kg and 0.23 μg/kg, respectively. The 17 common ions did not interfere even when present in 1,000-fold excess over the bromated ion of 10.0 μg/L. The accuracy was in a range of 92-104% and the assay precision was less than 9% in the table salt. The method was successfully applied to determine bromate in mineral water and table salt.