茶叶中儿茶素薄层色谱分离所用展开剂的优化

Optimization of developing solvents of high performance thin-layer chromatography for separating catechins in tea

室温条件下,以硅胶板为固定相,用5种展开剂(体积比9:9:2的甲苯-丙酮-甲酸、5.0:10.0:1.0:0.5的甲苯-甲酸乙酯-甲醇-甲酸、8.0:5.0:15.0:0.3的甲苯-三氯钾烷-丙酮-甲酸、12.5:7.5:1.8:0.6的三氯钾烷-丙酮-甲醇-水、12.5:7.5:1.8:0.6的三氯钾烷-丙酮-甲酸-水)对茶叶中的儿茶素进行薄层色谱分离,筛选出其中较优的展开剂后,进一步优化其配比,并用其分离绿茶和白茶提取物中的儿茶素以进行验证。结果表明,以体积比12.5:7.5:2.2的三氯甲烷-丙酮-甲酸为展开剂,茶叶内主要的4种儿茶素单体(EGCg、EGC、ECg、EC)可得到良好分离,绿茶与白茶提取物中的儿茶素能较好地得以分离。

At room temperature,methylbenzene-acetone-formic acid（9∶9∶2,V/V）,methylbenzene-ethyl formate-methanol-formic acid（5.0∶10.0∶1.0∶0.5,V/V）,methylbenzene-chloroform-acetone-formic acid（8.0∶5.0∶15.0∶0.3,V/V）,chloroform-acetone-methanol-water（12.5∶7.5∶1.8∶0.6,V/V） and chloroform-acetone-formic acid-water（12.5∶7.5∶1.8∶0.6,V/V） on silica gel marked as solventⅠ,Ⅱ,Ⅲ,Ⅳ and Ⅴrespectively were applied as developing solvent respectively in high performance thin-layer chromatography（HPTLC） for isolating catechins in the tea.Among them,solvent Ⅴ was found to be the best for separation of catechins,this solvent was then modified mainly regarding the volume ratios of formic acid.The results showed the modified solvent Ⅴ,namely,chloroform-acetone-formic acid（12.5∶7.5∶2.2,V/V） was the optimum for separation of the four main catechins（EGCg,EGC,ECg,EC） in the tea.The applicability of the optimized developing solvent was further confirmed by separation of catechins in the extracts of the green and the white tea.