Determination of banned 10 azo-dyes in hot chili products by gel permeation chromatography–liquid chromatography–electrospray ionization-tandem mass spectrometry

An accurate method based on the use of gel permeation chromatography (GPC)–liquid chromatography–tandem mass spectrometry interfaced with electrospray ionization (GPC–LC–ESI-MS/MS) was devised for the simultaneous determination of Sudan (I–IV), Sudan Orange G, Sudan Red B, Sudan Red G, Sudan Red 7B, Butter Yellow and Para Red in hot chili products. A GPC clean-up procedure was developed for simultaneous quantification of 10 dyes in hot chili and hot chili products avoiding some interference and permitting multiple injections without damaging the column. A HPLC was performed on an Inertsil C18 column using a multistep gradient elution with 0.1% formic acid and methanol as the mobile phase. Mass spectral acquisition was done in positive ion mode. Linearity of around three orders in the magnitude of concentration was generally obtained with the correlation coefficients (r2) of 0.9984–0.9997. Limit of detection (LOD) and limit of quantification (LOQ) for the investigated dyes were in the ranges of 0.1–1.8 and 0.4–5.0 μg/kg depending on matrices, respectively. The recoveries of the 10 synthetic dyes in five matrices ranged from 81.7 to 92.9%. The intra- and inter-day precision (RSDs) was between 2.9–7.8 and 3.9–8.1%, respectively. This method has been applied successfully for the determination of the studied 10 banned dyes in hot chili products.