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Journal of Chromatography A
Volume 1117, Issue 1, 2 June 2006, Pages 103-108
 
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doi:10.1016/j.chroma.2006.03.057    How to Cite or Link Using DOI (Opens New Window)
Copyright © 2006 Elsevier B.V. All rights reserved.

Analysis of green tea extract dietary supplements by micellar electrokinetic chromatography

David J. WeissCorresponding Author Contact Information, E-mail The Corresponding Author, Eric J. Austria, Christopher R. Anderton, Richard Hompesch and Ashley Jander

Department of Chemistry, University of Colorado at Colorado Springs, Colorado Springs, CO 80918, USA

Received 27 December 2005; 
revised 7 March 2006; 
accepted 20 March 2006. 
Available online 4 April 2006.

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Abstract

Dietary supplements are growing in popularity as a source of catechins such as epigallocatechin gallate (EGCG). The first determination of five catechins in green tea extract dietary supplements using an extraction followed by micellar electrokinetic chromatography (MEKC) with UV detection is presented here. The optimum run buffer is 5 mM borate–60 mM phosphate with 50 mM SDS at pH 7.00 with detection at 210 nm. The limit of detection is 2–3 μg/mL (S/N = 3) and the limit of quantitation is 6–8 μg/mL (S/N = 10). Results indicate that the amount of catechins varies greatly among manufacturers, between capsules of the same manufacturers, and between batches.

Keywords: Tea; Catechins; Dietary supplements; Epigallocatechin gallate

Article Outline

1. Introduction
2. Experimental
2.1. Chemicals
2.2. CE instrumentation
2.3. Preparation of standards and dietary supplement capsules
3. Results and discussion
3.1. Method development for analysis of green tea extract dietary supplements
3.2. Optimization of extraction efficiency for dietary supplement capsules
3.3. Analysis of dietary supplement extracts
4. Conclusions
Acknowledgements
References





 
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