title: Solid-phase extraction for the determination of caffeine in traditional Chinese medicinal prescriptions containing Theae folium by high performance liquid chromatography.
abstract: A high performance liquid chromatographic method in combination with C-18 reverse phase solid-phase extraction (SPE) was developed for determination of caffeine (CA) in traditional Chinese medicinal prescriptions which contain Theae folium. The frequently used prescriptions include Shin-Yi-San, Chuan-Chyong-Char-Tyau-San, Tsang-Eel-San, San-Hwang-Shyr-Gau-Tang, Tzy-Shenn-Ming-Mu-Tang and Shiang-Chyong-San. The present HPLC system uses a Merck RP-select B column by isocratic elution with methanol and 1% (v/v) acetic acid (1:4) as the mobile phase and detected at UV 270 nm. 8-Chlorotheophylline was used as an internal standard. The extracts of prescriptions were treated by Supelclean LC-18 SPE tube for eliminating interferences. Blank decoctions of each prescription were also examined as a test for interferences. The recoveries of caffeine from the Chinese medicinal prescriptions ranged from 88.5 to 92.3%. The relative standard deviations of caffeine ranged between 0.86 and 1.97% (intraday) and 1.04 and 3.90% (interday). The contents of caffeine in standard decoctions ranged from 13.98 to 19.62 mg g(-1).
authors.affiliation: Institute of Chinese Pharmaceutical Sciences, China Medical College, Taichung, Taiwan, ROC.
authors.forename: Y R
authors.initials: YR
authors.lastname: Ku
authors.forename: K C
authors.initials: KC
authors.lastname: Wen
authors.forename: L K
authors.initials: LK
authors.lastname: Ho
authors.forename: Y S
authors.initials: YS
authors.lastname: Chang
mesh_terms: D002110:Caffeine / Q000032:analysis*; D002138:Calibration; D000697:Central Nervous System Stimulants / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D004365:Drugs, Chinese Herbal / Q000032:analysis*; D020448:Ericales / Q000737:chemistry*; D007202:Indicators and Reagents; D015203:Reproducibility of Results; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet; D013662:Tea / Q000737:chemistry
chemical_list: D000697:Central Nervous System Stimulants; D004365:Drugs, Chinese Herbal; D007202:Indicators and Reagents; D012996:Solutions; D013662:Tea; D002110:Caffeine