Coupling of a streamlined solid-liquid extraction protocol with LC-ESI-MS/MS for the regular oversight of illegal...

A reliable solid-liquid extraction protocol coupled with liquid chromatography-electrospray ionization-tandem mass spectrometry in the negative-ion mode was developed and validated for illegal bromate determination in preliminary and bakery products. Crude and dried-treated samples were directly extracted with acetonitrile-water (4:1, v/v). Bromate was determined using a Phenomenex Synergi™ Polar reversed-phase column and MS/MS under multiple reaction monitoring. The chosen solvent efficiently extracted bromate with all applied extraction-assisting techniques (p > 0.05). Although this assay avoids cleanup procedures, matrix effect of <-11% was achieved. Rapid bromate separation in only 8 min was attained by a reversed-phase column. In both commodities, linearity range, R², recovery%, repeatability, intermediate precision, LOD and LOQ results were 0.05-100 ng mL^-1, >0.9999, 88.6-103%, 2.93-9.80% and 9.64-10.10%, 0.015 μg kg^-1 and 0.05 μg kg^-1, respectively. Out of 288 tested real samples, 13.9% of violations were observed. This high-sensitivity protocol offers effective oversight and consumer protection.