Development and validation of a LC-MS/MS method for the simultaneous determination of aflatoxins, dyes and pesticides in spices

Based on several alerts from European countries over the last years concerning spices, we have been encouraged to establish an accurate method for the determination of dyes, aflatoxins and pesticides in various types of spices using reversed-phase (RP) liquid chromatography-tandem mass spectrometry interfaced with electrospray (LC-ESI-MS/MS). A simple sample treatment procedure entailing the use of an extraction step with acetonitrile without further cleanup has been developed. A C18 column with an aqueous ammonium formate/methanol mixture as the mobile phase was used, and gradient elution was performed. Mass spectral acquisition was done in positive ion mode by applying multiple reaction monitoring of at least two fragmentation transitions per compound to provide a high degree of selectivity. The method was in-house validated in terms of linearity, sensitivity, repeatability, recovery and selectivity on six kinds of spices. Satisfactory results in the majority of the cases were obtained for all analytes and matrices, with practical limits of quantitation acceptable for routine monitoring purposes. Extraction recoveries for most of the compounds ranged from 60% to 140% at spiking levels of 0.05 and 0.5 mg kg⁻¹. The applicability of the method for the simultaneous determination of dyes, aflatoxins and pesticides in several types of spices was demonstrated, and the method successfully applied to a limited number of products from the local market.