Electron-impact and glow-discharge ionization LC–MS analysis of green tea tincture

Venzie, Jacob L.; Castro, Joaudimir; Balarama Krishna, M. V.; Nelson, Dwella M.; Marcus, R. Kenneth
January 2007
Analytical & Bioanalytical Chemistry;Jan2007, Vol. 387 Issue 1, p321
Academic Journal
A liquid chromatography–particle-beam mass spectrometer (LC–PB/MS) with interchangeable electron-impact (EI) and glow-discharge (GD) ion sources was evaluated for future application in analysis of botanical extracts. In this work a green tea tincture was characterized for a series of catechin components (catechin, epicatechin, epigallocatechin, and epigallocatechin gallate (EGCG)) and caffeine. Special emphasis was given to EGCG and caffeine, because they are important in determining the possible health effects of the green tea. The effects of instrument operating conditions were evaluated for the EI and GD ionization sources to determine their effect on analyte intensities and fragmentation patterns. These studies furnished information about the effects of these conditions in determining possible ionization pathways in the two ion sources. The mass spectra of these compounds obtained with the GD ion source are EI-like in appearance, with clearly identified molecular ions and fragmentation patterns that are easily rationalized. The absolute limits of detection for EGCG and caffeine were, respectively, 11 ng and 0.77 ng for the EI source and 3.2 ng and 0.61 ng for the GD source. The PB/EIMS and PB/GDMS combinations can be operated in a flow-injection mode, wherein the analyte is injected directly into the mobile phase, or coupled to high-performance liquid chromatography (HPLC), enabling LC–MS analysis of complex mixtures. A reversed-phase chromatographic separation of the green tea tincture was performed on a commercial C18 column using a gradient of water (containing 0.1% TFA) and ACN. Quantification of EGCG and caffeine was performed by the standard addition method. The amounts of EGCG and caffeine in the tested green tea tincture were each ∼14 mg mL−1.


Related Articles

  • Analyzing Green Tea Leaves and Supplements. Bliss, Rosalie Marion // Food & Nutrition Research Briefs;Jul2012, p2 

    The article discusses the findings of a study by the U.S. Department of Agriculture (USDA) which examined the phytochemical properties of brewed green tea leaves and green tea dietary supplements. Scientists at the Agricultural Research Service confirmed the degradation of phytonutrients like...

  • Catechins in Dietary Supplements and Hepatotoxicity. Navarro, Victor; Bonkovsky, Herbert; Hwang, Sun-Il; Vega, Maricruz; Barnhart, Huiman; Serrano, Jose // Digestive Diseases & Sciences;Sep2013, Vol. 58 Issue 9, p2682 

    Background: Many herbal dietary supplements (HDS) contain green tea extract (GTE) and its component catechins, although their presence may not always be indicated on the product label. Purpose: Because GTE and catechins have been implicated in human hepatotoxicity in several case reports, our...

  • Green Teas Vary in Strength and Amount of Lead Contamination.  // Townsend Letter;Jan2014, Issue 366, p20 

    The article discusses a research study which examined the variation of catechin and caffeine levels in several brands of green tea. It references the study "Green Tea Supplements, Drinks and Brewable Teas Review" by ConsumerLab.com. The study found that the amount of tea leaf in suggested...

  • FOODS FOR A FLAT TUMMY.  // Good Housekeeping;Jul2009, Vol. 249 Issue 1, p136 

    The article presents suggestions concerning dietary supplements for weight loss. For weight loss, consumption of whole grains such as oats and barley is suggested. Intake of water-rich foods such as tomatoes, cucumbers, lettuce, melons and oranges is suggested. To reduce waist size as well as...

  • Characterizing Vaccinium berry Standard Reference Materials by GC-MS using NIST spectral libraries. Lowenthal, Mark; Andriamaharavo, Nirina; Stein, Stephen; Phinney, Karen // Analytical & Bioanalytical Chemistry;May2013, Vol. 405 Issue 13, p4467 

    A gas chromatography-mass spectrometry (GC-MS)-based method was developed for qualitative characterization of metabolites found in Vaccinium fruit (berry) dietary supplement Standard Reference Materials (SRMs). Definitive identifications are provided for 98 unique metabolites determined among...

  • Evaluation of cost versus antioxidant determinants in green tea dietary supplements. Roberson, Cindy Leslie A.; Abourashed, Ehab A.; Elsharkawy, Nancy // Journal of the American Pharmacists Association: JAPhA;Jul/Aug2015, Vol. 55 Issue 4, p381 

    Objective: To investigate the association between cost and (a) chemical constituents and (b) antioxidant activity as quality determinants of select green tea supplements available in the United States. Design/setting. Laboratory analysis of green tea using HPLC and antioxidant assay methods....

  • Production of atomic hydrogen in an rf gas discharge and mass spectrometer diagnostics of the process. Akulov, Yu. A.; Mamyrin, B. A.; Shikhaliev, P. M. // Technical Physics;May97, Vol. 42 Issue 5, p584 

    Investigates the production of atomic hydrogen in an rf gas discharge. Mass spectrometry diagnostic of the process; Use of thermal dissociation in the production of atomic hydrogen.

  • Secondary-neutral microprobe with electron-gas post-ionization. Bieck, W.; Gnaser, H. // Applied Physics Letters;8/9/1993, Vol. 63 Issue 6, p845 

    Examines the features and performance of secondary-neutral microprobe with electron-gas post-ionization. Operation of the device at high mass spectrometer; Use of secondary-neutral mass spectroscopy for isotope analysis; Generation of secondary-neutral intensity caused by high transmission of...

  • Catalysis by hen egg-white lysozyme proceeds via a covalent intermediate. Vocadlo, David J.; Davies, Gideon J.; Laine, Roger; Withers, Stephen G. // Nature;8/23/2001, Vol. 412 Issue 6849, p835 

    Deals with a study that showed a catalytically competent covalent glycosyl-enzyme intermediate during the catalytic cycle of hen egg-white lysozyme (HEWL), through different cases using electrospray ionization mass spectrometry. Composition of HEWL; Arguments on the nature and purported...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics