Study of several aspects of a general method for the determination of polycyclic aromatic hydrocarbons in liquid smoke flavourings by gas chromatography-mass spectrometry

The effectiveness of the steps of a general method, which includes alkaline treatment of the samples, extraction, clean-up and analysis, for the determination of polycyclic aromatic hydrocarbons in liquid smoke flavourings and smoked foods have been studied, by using mixtures of pure polycyclic aromatic hydrocarbons and of smoke flavouring compounds. All these products were applied to samples of liquid smoke flavourings in order to test the effectiveness of each step of the method as well as to investigate its effect on real samples, and thus obtain a suitable procedure for the study of polycyclic aromatic hydrocarbons in liquid smoke flavourings. The alkaline treatment has been proved to be necessary because of its capability for removing some smoke components. Both cyclohexane and dichloromethane are able to extract polycyclic aromatic hydrocarbons with high recovery percentages; however, cyclohexane is more adequate due to its lower ability to extract other smoke flavourings components. It is important to note that the elution sequence of polycyclic aromatic hydrocarbons during the clean-up step is quite different depending on the solvent used to dissolve the extract, which determines the ability of this process to isolate polycyclic aromatic hydrocarbons for their accurate identification and quantification by gas chromatography-mass spectrometry in selected ion monitoring mode. Finally, the PAHs present in a liquid smoke flavouring and their concentrations were determined; it was observed that, despite the different extraction solvents and clean-up procedures used, the results were very similar.