Analysis of contaminant polycyclic aromatic hydrocarbons in tea products and crude drugs

Tea products and crude drugs were analyzed to determine levels of contamination with 15 polycyclic aromatic hydrocarbons (PAHs) using a new online automated method, consisting of in-tube solid-phase microextraction (SPME) coupled with high-performance liquid chromatography-fluorescence detection (HPLC-FLD). PAHs were separated within 15 min by HPLC using a Zorbax Eclipse PAH column with a water/acetonitrile gradient elution program as the mobile phase. The optimum in-tube SPME conditions were 20 draw/eject cycles of 40 mu L of sample using a CP-Sil 19CB capillary column as an extraction device. Low- and high-molecular weight PAHs were extracted effectively onto the capillary coating from 5% and 30% methanol solutions, respectively. The extracted PAHs were readily desorbed from the capillary by passage of the mobile phase. Good linearity of the calibration curve (r > 0.9972) was obtained in the concentration range of 0.05-2.0 ng mL(-1), and the detection limits (S/N = 3) of PAHs were 0.32-4.63 pg mL(-1). Using the in-tube SPME/HPLC-FLD method, PAHs were detected at ng g(-1) levels in the samples without interference peaks. Our results suggest that PAHs contamination in herbal products is widespread, and the proposed method may become a useful tool for monitoring PAH contamination and quality control in herbal products.