Modular Method for the Determination of Polycyclic Aromatic Hydrocarbons in Spices and Dried Herbs by Gas Chromatography–Tandem Mass Spectrometry

Abstract

This paper describes a method for quantification of the four regulated polycyclic aromatic hydrocarbons (PAHs), (benzo[a]anthracene [BaA], chrysene [CHR], benzo[b]fluoranthene [BbF] and benzo[a]pyrene [BaP]), in the wide matrix group of spices and dried herbs by gas chromatography–tandem mass spectrometry (GC–MS/MS). The design of this method was drawn up using basic material and equipment available in most laboratories and a modular clean-up fitting for each category of this very diverse matrix group. The clean-up strategy consists of dividing this matrix group into three subclasses: regular spices, highly pigmented matrices and complex mix of spices/fatty spices. Depending on the subclass, SPE sorbent is adapted to remove maximum of co-extracts and to obtain clean samples. This method has a limit of quantification of 0.5 μg kg⁻¹ for each PAH and the validation criteria fully satisfied the Commission Regulation (EU) No. 836/2011 (< 0.9 μg kg⁻¹). The quantification performed by isotopic dilution allowed the complete correction of matrix effect and led to very good validation data with a mean recovery close to 100% and a within-laboratory reproducibility below 10% (≤ 22% in Regulation (EU) No. 836/2011) for each PAH and for each matrix group at all concentration levels tested. Furthermore, the method’s performance characteristics have been successfully assessed using a representative certified reference material for each subclass and at a level close to the MRL: 10 μg kg⁻¹ for BaP and 50 μg kg⁻¹ for the sum of the 4 PAHs.