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Recently, 9,10-anthraquinone(AQ) contamination in Chinese Liupao tea has attracted much attention because the tea for exportation must meet the EU limit(20 µg·kg-1). In this study, the sample pretreatment methods were optimized from the aspects of extraction reagent and purification column filler. Finally, n-hexane acetone was selected as the optimal extraction agent. When the content of Florisil in the purification column was 1.0 g, the purification effect was the best. The new method reduces the limit of quantification (LOQs) of AQ to 10 μg·kg-1, and the detection accuracy has also been further improved. The recovery of 9,10-anthraquinone-fortified tea samples (20-100 μg·kg-1) was 94.51-100.44%, and the relative standard deviation (RSD) was less than 1.31%. In this study, 98 Liupao tea samples on the market were tested by the new method. It was found that 61 samples were positive (occurrence rate 63.3%), and the AQ content of 55 positive samples was higher than the EU limit (20 µg·kg-1). This study also found that the pollution of AQ in Liupao tea increased with the growth of aging time. The source of AQ in the aging process of Liupao tea will be the focus of further research. |
