Determination of adulterants in whey protein food supplements by liquid chromatography coupled to Orbitrap high resolution mass spectrometry

Abstract Liquid chromatography coupled to Orbitrap high resolution mass spectrometry was shown to be an adequate technique to control the adulteration of whey protein food supplements with prohibited substances, not declared on the labels. An extraction method combined with an instrumental analysis that allowed for the determination of 105 substances in whey protein food supplements, was established. The pre-treatment of the samples consisted of protein precipitation and solid-phase extraction using weak cation exchange functionalized polymeric sorbent cartridges. The samples were directly analyzed by LC-Orbitrap-HRMS. The selectivity, limit of detection, repeatability, recovery, carryover and matrix effect were estimated as the validation parameters. The repeatability obtained was 96.19% and the recovery 83.80%, but carryover and the matrix effect were not observed. The present method was successfully applied to the analysis of commercial samples, verifying adulteration by diuretics (conivaptan and politiazide) and a stimulant (benfluorex) in seven of the eleven brands evaluated.