New procedure for selective extraction of polycyclic aromatic hydrocarbons in plants for gas chromatographic-mass spectrometric analysis.

A new solid-phase extraction method for the clean-up and the quantitation by GC-MS of regulated polycyclic aromatic hydrocarbons (PAHs) from lettuce was developed and the experimental conditions were optimized. After ultrasonic extraction using toluene and saponification of samples, a clean-up of extracts through solid-phase extraction was performed. Samples were finally analyzed by gas chromatography-mass spectrometry (GC-MS) using an internal deuterated standard. Saponification by KOH in methanol-water (80:20) was successful allowing a good elimination of the interfering chlorophylls from the extracts containing the PAHs. The average recovery of the 16 regulated PAHs was 70, 74, 79 and 89%, respectively, for naphthalene, acenaphthylene, acenaphthene and chrysene and higher than 94% for the others.