Optimization of a sampling method to determine polycyclic aromatic hydrocarbons in smoke from incomplete biomass combustion

A method of sampling for the determination of polycyclic aromatic hydrocarbons (PAHs) and their methyl derivatives in smoke samples from the incomplete combustion of different types of biomass is developed. The smoke is used for the smoking of foods, following an artisan procedure used in some places in the Canary Islands. By means of a factorial design, the variables with more influence in the sampling have been optimized: sampling temperature, sampling flow and composition of the adsorbent. The used sampling system is formed by a quartz fibre filter and an adsorbent constituted by PUF/XAD-2/PUF. For the treatment of the sample, the procedure described in UNE-77250 regulation is used, and the determination is carried out by gas chromatography–mass spectrometry. The results obtained in the present work show the necessity to analyse the filter and the adsorbent together, and that the retention efficiencies, when the temperature of the smoke is not too high, are usually >70%. Also, it is shown that for a correct interpretation of the results obtained when establishing the content of PAHs and their methyl derivatives in the smoke samples, it is necessary to take into consideration the temperature of the smoke at the point of sampling.