SWATH-MS screening strategy for the determination of food dyes in spices by UHPLC-HRMS

A multi-class wide-scope screening method for the detection and identification of artificial colours and illegal dyes in spices was developed for regulatory purposes. The screening was carried out by ultra-high performance liquid chromatography hyphenated with a quadrupole/time-of-flight mass spectrometry (UHPLC-QTOF-MS) with sequential window acquisition of all theoretical fragment-ion spectra (SWATH) and was validated with forty-one compounds by spiking experiments in curry and paprika extracts. In order to detect and identify the compounds with a high level of confidence, a home-made tandem mass spectrometry (QTOF-MS/MS) database of approximately one hundred illegal dyes and artificial colours was created. The procedure was then used to screen field samples of spices and spice blends purchased from Swiss markets. Sudan IV, Sudan I, bixin (E160b) and Ponceau 4R (E124) were all detected among the eight non-compliant samples.