反相高效液相色谱法直接测定茶叶水提取物中的嘌呤碱

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２７０ｎｍ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８ｍｇ／Ｌ，峰面积标准曲线在６～１０００ｍｇ／Ｌ范围内具有良好的线性关系，线性相关系数为０９９８以上。

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

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-C18(4.6 mm i.d. x 250 mm, 5 microns) 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.