[Theanine, EGCG and caffeine determinated by HPLC].
OBJECTIVE
A high-performance liquid chromatography (HPLC) method was developed for the determination of theanine in puer tea without derivatization and HPLC for EGCG and caffeine with ingredient elution system was put forward.


METHODS
The theanine in the tea was extracted with water. The EGCG and caffeine was extracted with water: ethanol (3:7) by ultrasonic oscillation. After centrifugation, the extract was analyzed by HPLC-PDAD with a C18column and at the flow rate 1 ml/min. The theanine was determinated with 5 mmol/L SDS-acetonitrile mobile phase system (72:28), and both EGCG and caffeine with 0.05 mmol/L KH2PO4-methonal mobile phase system (80:20).


RESULTS
The calibration of three ingredients was in good linearity. The recovery range is 85%-110%. The RSD is less than 10%.


CONCLUSIONS
The method is accurate and stable.
Diao
Feiyan
F
Department of Chemical and Bacterial Detection, School of Public Health, Shandong University, Ji'nan 250012, China. diaofeiyan321@163.com
Dong
Fengming
F
Wang
Qiuli
Q
Liu
Na
N
Guo
Dongmei
D
Cui
Xi
X
D002110:Caffeine / Q000032:analysis*; D002392:Catechin / Q000031:analogs & derivatives* / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D005971:Glutamates / Q000032:analysis*; D012680:Sensitivity and Specificity; D013662:Tea / Q000737:chemistry*
D005971:Glutamates; D013662:Tea; D002110:Caffeine; C026166:theanine; D002392:Catechin; C045651:epigallocatechin gallate