Determination of Polycyclic Aromatic Hydrocarbons in Vegetables by Headspace SPME-GC

A simple, sensitive and inexpensive method has been developed for the quantitative determination of eight polycyclic aromatic hydrocarbons (PAHs) in vegetables based on headspace solid-phase microextraction coupled with gas chromatography using a sol-gel calix[6]arene-containing fiber. Parameters related to the extraction efficiency such as extraction temperature, extraction time, ionic strength, stirring speed, and solvents' addition were evaluated and optimized. Owing to the good selectivity and high extraction capability of the sol-gel calix[6]arene-containing fiber, low detection limits of 0.04-2.32 ng g(-1) and good linearities with linear correlation coefficients > 0.9964 were obtained. The relative standard deviation values were < 11.6% for all of the PAHs. Average recoveries ranged from 81.07 to 107.5%. The method was applied to analyze nine kinds of vegetables near South Lake, Wuhan, China. The total concentrations of PAHs in these vegetables were found to vary between 3.91 and 96.98 ng g(-1) wet weight with 2- and 3-ring PAHs predominating. Generally speaking, PAHs levels in leafy vegetables were higher than those in fruit vegetables, and root and subterranean stem vegetables had the lowest levels. The effect of cooking methods on PAHs concentration in vegetables was tested, and the results showed that PAHs in vegetables reduced a little after blanching, and was not detected after stir-frying.