Supercritical fluid extraction of mononitrated polycyclic aromatic hydrocarbons from tea – correlation with the PAH concentration

 The ability of supercritical fluid extraction (SFE) to extract nitropolycyclic aromatic hydrocarbons (nitro-PAHs) from tea matrices is described and discussed. An experimental approach was set up to determine the influences of various extraction parameters, i. e. pressure, temperature, extraction time and addition of modifier. The evaluation of the method was carried out by analysing samples of fortified tea and then comparing the results with those obtained from conventional extraction procedures, such as Soxhlet extraction and ultrasonication. SFE proved to be far better than the conventional methods at monitoring levels of nitro-PAHs in tea. However, due to the wide range of polarity of the analytes investigated, selective extraction with supercritical carbon dioxide was not possible; hence, subsequent purification steps were necessary, prior to the final GC/MSD analyses. The nitro-PAHs and PAHs concentrations in several tea samples were determined, any correlation between nitro-PAHs and PAHs was studied and the results are presented in this article.