An Improved Lipid Elimination Method Using SPE Combined With GP-MSE For The Determination Of Polycyclic Aromatic Hydrocarbons In Tree Leaves

We developed a simple and fast lipids eliminating method in extracts of tree leaves and analyzed the affect of lipids elimination to PAHs detection. Composition of lipids in nineteen kinds of tree leaves were qualitatively and quantitatively analyzed, results showed that lipids in broad-leaf tree leave extracts are mainly hydrocarbons, squalene and triterpenes, and lipids in conifer extracts are mainly sesquiterpenoids, hydrocarbons and triterpenes. The lipids were successfully removed from the extracts through the proposed two-step cleanup procedures which is a combination of SPE and Gas purge microsyringe extraction (GP-MSE) technique. Lipids eliminated by SPE were mainly esters, alcohols, amides, ketones, triterpenes and a part of alkanes, and by GP-MSE were mainly high molecular alkanes, triterpenes and non-volatile chemicals such as polyacids and polyphenols. Eliminating rates of the lipids for different tree leave extracts are more than 99%, it is favor to reduce interferening chemicals, decrease method detection limit of PAHs in analysis of tree leaves, and.can protect the analysis system, increase reproducibility of consecutive analysis.The recoveries and relative standard deviations (R.S.D.) ranged from 74 to 90% with an average of 86% and from 0.8 to 12.1% with an average of 5.2% for spiked willow extract, respectively. The concentrations of PAHs ranged from nd to 363.8 ng g-1 and LOD ranged from 0.02 to 0.08 ng g-1 for willow extract. The method was applied in determination of PAHs in various tree leaves, and it were compared with other methods in various analytical parameters such as amount of solvent, sample treatment time, and LOD, etc. The two-step cleanup method have the advantages of simple, fast, save solvent and sample with highly accuration sensitivity and reproducibility. It is suitable for determination of PAHs in various tree leaves.