ScienceAsia 33 (2007): 113-117 |doi: 10.2306/scienceasia1513-1874.2007.33.113
Validation of Isocratic Eluting and Stepwise Flow Rate
Gradient for HPLC Determination of Catechins,
Gallic Acid and Caffeine in Tea
Pokpong Prayonga, Natthida Weerapreeyakula, b and Bungorn Sripanidkulchaia, b*
ABSTRACT: An easy, rapid and precise high performance liquid chromatographic determination for catechins,
gallic acid and caffeine in tea with an isocratic elution and stepwise flow rate gradient was developed. The
chromatographic separation system consisted of a C18 reverse phase column, and an isocratic elution system
of 16:1:3 (0.1% ortho phosphoric acid-methanol-acetonitrile). The validation of this method was confirmed
from specificity, linearity, precision, accuracy, limit of detection and limit of quantification. The method
exhibited good linearity and accuracy and has been used to analyze commercial tea products. The results
showed high amounts of (+) epigallocatechin gallate, caffeine and (+) catechin in these products, ranging
from 206±13 to 9,630±56, 137±13 to 4,870±130 and <1.29 to 1,790±7 mg/100g dried weight, respectively.
The amounts of gallic acid, (-) gallocatechin gallate and (-) epicatechin gallate found were14.9±0.3 to
104±0.4, <14.2 to 399±67, 122±8 to 3,020±45 mg/100g dried weight, respectively.
KEYWORDS: HPLC, stepwise flow rate gradient, green tea, catechin, gallic acid, caffeine, antioxidant.
a Center for Research and Development in Herbal Health Product (CRD-HHP), Khon Kaen University, Khon
Kaen 40002, Thailand.
b Department of Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, Khon Kaen University,
Khon Kaen 40002, Thailand.
* Corresponding author, E-mail: firstname.lastname@example.org
Received 17 Mar 2006,
Accepted 26 Jul 2006