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Electron-impact and glow-discharge ionization LC-MS analysis of green tea tincture.
Anal Bioanal Chem. 2007 Jan; 387(1):321-33.AB

Abstract

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 approximately 14 mg mL-1.

Authors+Show Affiliations

Department of Chemistry, Clemson University, Biosystems Research Complex, 51 New Cherry St., Clemson, SC 29634-1905, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17139484

Citation

Venzie, Jacob L., et al. "Electron-impact and Glow-discharge Ionization LC-MS Analysis of Green Tea Tincture." Analytical and Bioanalytical Chemistry, vol. 387, no. 1, 2007, pp. 321-33.
Venzie JL, Castro J, Balarama Krishna MV, et al. Electron-impact and glow-discharge ionization LC-MS analysis of green tea tincture. Anal Bioanal Chem. 2007;387(1):321-33.
Venzie, J. L., Castro, J., Balarama Krishna, M. V., Nelson, D. M., & Marcus, R. K. (2007). Electron-impact and glow-discharge ionization LC-MS analysis of green tea tincture. Analytical and Bioanalytical Chemistry, 387(1), 321-33.
Venzie JL, et al. Electron-impact and Glow-discharge Ionization LC-MS Analysis of Green Tea Tincture. Anal Bioanal Chem. 2007;387(1):321-33. PubMed PMID: 17139484.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Electron-impact and glow-discharge ionization LC-MS analysis of green tea tincture. AU - Venzie,Jacob L, AU - Castro,Joaudimir, AU - Balarama Krishna,M V, AU - Nelson,Dwella M, AU - Marcus,R Kenneth, Y1 - 2006/12/01/ PY - 2006/05/24/received PY - 2006/10/12/accepted PY - 2006/10/02/revised PY - 2006/12/2/pubmed PY - 2007/6/19/medline PY - 2006/12/2/entrez SP - 321 EP - 33 JF - Analytical and bioanalytical chemistry JO - Anal Bioanal Chem VL - 387 IS - 1 N2 - 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 approximately 14 mg mL-1. SN - 1618-2642 UR - https://www.unboundmedicine.com/medline/citation/17139484/Electron_impact_and_glow_discharge_ionization_LC_MS_analysis_of_green_tea_tincture_ L2 - https://dx.doi.org/10.1007/s00216-006-0934-z DB - PRIME DP - Unbound Medicine ER -