反相高效液相色谱法直接测定茶叶水提取物中的嘌呤碱

Direct Determination of Purine Bases in Tea by Reversed Phase High Performance Liquid Chromatography

用反相高效液相色谱法直接测定茶叶水提取物中的咖啡因、可可碱和茶碱，方法简便快速。在 ２７０ ｎｍ 检测波长下，可可碱、茶碱和咖啡因的检测下限分别为 ０７，０９ 和 １８ ｍ ｇ／ Ｌ，峰面积标准曲线在 ６～１ ０００ ｍ ｇ／ Ｌ范围内具有良好的线性关系，线性相关系数为 ０９９８

A reversed phase high performance liquid chromatographic(RP HPLC) method for the direct determination of three purine bases(theobromin, theophyllin and caffeine) in tea was developed. An ODS column with Zorbax SB C 18 (4.6 mm i.d.×250 mm,5 μm)was employed. The aqueous solution of methanol containing 0 05% of acetic acid and 0.25% of N,N dimethylformamide(DMF) was used as eluent with a flow rate of 0.8 mL/min. In this method, the aqueous extract of tea can be injected into HPLC directly, but in current HPLC methods for purine bases the coexisted tea polyphenols must be pre separated . The three purine bases in tea were separated without any interference from the coexisted tea polyphenols. This method is simple(without any special sample pretreatment) and sensitive with detection limits (S/N=3) of 0.7, 0.9 and 1.8 mg/L for theobromin, theophyllin and caffeine respectively. The linear range of the calibration curve of peak area for the three purine bases were from 6 mg/L to 1 000 mg/L with a correlation coefficient (r) of 0.998 0.999.