Detection of Perchlorate in Tea Leaves and Analysis of the Pollution Situation

In this paper, the pollution of perchlorate content in some commercially sold tea was analyzed, so as to provide some reference for establishing the limit and detection standards of perchlorate, standardizing the tea production, improving the tea quality and strengthening the supervision of tea industry in China. The tea samples with different tea types from different regions were randomly purchased from the market, and then separated by the Obelisc R chromatographic column and determined by using the high performance liquid chromatography-tandem mass spectrometry, the pollution of perchlorate in 4 kinds of tea from 4 regions and 11 provinces in China was quantitatively analyzed by using the ¹⁸O sodium perchlorate isotope internal standard method. The results showed that the perchlorate was detected in 62 batches of the 88 samples from 4 kinds of tea in 4 administrative regions of China, with a detection rate of 70.5%. The content of perchlorate in the samples ranged from 0.038 to 1.750 mg·kg^-1, with an average detection value of 0.268 mg·kg^-1. There were 4 batches of tea in East, South and central China with the content of perchlorate>0.75 mg·kg^-1, accounting for 4.5% of the total batches, including black tea, green tea, oolong tea and dark green tea. Among them, the perchlorate content of a batch of green tea in South China was the highest, reaching 1.75 mg·kg^-1. The above analysis showed that the detection rate of perchlorate in some commercially available tea leaves was high. Combined with the average, median, minimum and maximum values of the detected contents, the pollution degree of green tea was higher than that of black tea, oolong tea and dark green tea, while the pollution degree of black tea was the lowest compared with other kinds of tea. If the limit value of 0.75 mg·kg^-1 proposed by the European Union was taken as the reference, the safety risk of green tea was higher, and there was certain risk of perchlorate pollution in the tea leaves in different regions of East, central and South China, which should be paid attention to by relevant departments.