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目的建立乌龙茶中咖啡因、表儿茶素、儿茶素、表没食子儿茶素、表没食子儿茶素没食子酸酯和表儿茶素没食子酸酯的含量测定方法。方法采用RP-HPLC,色谱柱为Grace Allitima C18(4.6 mm×250 mm,5μm),以乙腈-0.2%乙酸为流动相,梯度洗脱,流速为1.0 m L·min-1,检测波长为280 nm,柱温为35℃。结果咖啡因、表儿茶素、儿茶素、表没食子儿茶素、表没食子儿茶素没食子酸酯和表儿茶素没食子酸酯的质量浓度分别在13.38~2 140、6.36~1 018、5.95~952、6.55~1 048、10.83~1 732、7.80~1 248μg·m L-1内呈良好线性关系,相关系数分别为1.000、0.999 9、0.999 9、0.999 9、0.999 5、0.999 6;平均回收率分别为101.14%(RSD=2.06%,n=9)、100.26%(RSD=3.50%,n=9)、102.12%(RSD=4.45%,n=9)和99.57%(RSD=2.08%,n=9)、100.83%(RSD=2.13%,n=9)和99.12%(RSD=2.49%,n=9)。结论该方法简便、准确、重现性好,可用于乌龙茶的质量控制。不同产地、不同品牌的乌龙茶中咖啡因和5种儿茶素类指标成分含量差异较大。
Objective To establish a method for the determination of caffeine, epicatechin, catechin, epigallocatechin, epigallocatechin gallate and epicatechin gallate in oolong tea. Methods The analytical column was Grace Allitima C18 (4.6 mm × 250 mm, 5 μm) with gradient elution with acetonitrile-0.2% acetic acid as mobile phase at a flow rate of 1.0 mL · min-1 using RP-HPLC. The detection wavelength was 280 nm, the column temperature is 35 ℃. Results The mass concentrations of caffeine, epicatechin, catechin, epigallocatechin, epigallocatechin gallate and epicatechin gallate ranged from 13.38 to 2140 and 6.36 to 1018, respectively. 5.95 ~ 952,6.55 ~ 1 048,10.83 ~ 1 732,7.80 ~ 1 248μg · m L -1, the correlation coefficients were 1.000,0.999 9,0.999 9,0.999 9,0.999 5,0.999 6 respectively; The average recoveries were 101.14% (RSD = 2.06%, n = 9), 100.26% (RSD = 3.50%, n = 9), 102.12% (RSD = 4.45%, n = 9) and 99.57% %, n = 9), 100.83% (RSD = 2.13%, n = 9) and 99.12% (RSD = 2.49%, n = 9). Conclusion The method is simple, accurate, reproducible and can be used for the quality control of oolong tea. Different origin, different brands of oolong tea caffeine and five kinds of catechins indicators of the content of large differences.