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Determination of caffeine and its metabolites in human skin homogenate by high-performance liquid chromatography.

Authors
Zang-LY; DeHaven-JI; Soderholm-SC
Source
Proceedings of the International Conference on Occupational and Environmental Exposures of Skin to Chemicals: Science & Policy, Arlington, VA, September 8-11, 2002. Morgantown, WV: National Institute for Occupational Safety and Health, 2002 Sep; :1
Link
NIOSHTIC No.
20027265
Abstract
A method has been developed for the separation and quantification of caffeine and its metabolites in human skin homogenate. The method development was based on high-performance liquid chromatography (HPLC) equipped with UV-visible diode array detector and a Symmetry Shield RP8 column (3 mm, 2.1 mm x 150 mm). Beta-hydroxyethltheophylline (ISTD) was used as the internal standard for quantitation. The analytes in human skin homogenate were extracted with a Waters Oasis HLB solid phase extraction plate or by liquid-liquid extraction using methanol-methylene chloride (1:2, v/v). The mobile phase consisted of 20 mM ammonium acetate and acetonitrile at the gradient ratios from 100:0 for 5.5 min to 90:10 for 10 min at a constant flow rate of 0.3 mL/min. The compounds were monitored at 275 nm and a reference wavelength 360 nm with 100 nm widths. The elution order of these species was found to be 3-methyluric acid, 7-methyluric acid, 1-methyluric acid, 37-methyluric acid, 17-dimethyluric acid, 13-dimethyluric acid, 7-methylxanthine, 3-methylxanthine, 1-methylxanthine, 37-dimethylxanthine, 17-dimethylxanthine, 13-dimethylxanthine, ISTD, and 137-methylxanthine. The limits of quantification (LOQ) for these compounds were 1.0 - 2.5 ng per total injection. Reproducibility of the sample handling and HPLC assay had a relative standard deviation of +/- 10%. The average recoveries were better than 90% for liquid-liquid extraction and 82% for solid phase extraction.
Keywords
Metabolites; Chromatographic-analysis; Analytical-methods; Skin-tests; Skin; Quantitative-analysis; Analytical-processes; Analytical-chemistry
Publication Date
20020908
Document Type
Abstract
Fiscal Year
2002
NTIS Accession No.
NTIS Price
NIOSH Division
HELD
Source Name
Proceedings of the International Conference on Occupational and Environmental Exposures of Skin to Chemicals: Science & Policy, Arlington, VA, September 8-11, 2002
State
WV; VA
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