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Separation, pre-concentration, and HPLC analysis of methylxanthines in urine samples.

Journal of separation science (2004-11-13)
Mirosława Zydroń, Jacek Baranowski, Irena Baranowska
ABSTRACT

An SPE method, using RP18 phases, for the simultaneous extraction of caffeine, theobromine, theophylline, paraxanthine, 1-methylxanthine, 3-methylxanthine, 7-methylxanthine, 1-methyluric acid, 1,3-dimethyluric acid, 1,7-dimethyluric acid, and 1,3,7-trimethyluric acid from urine has been developed. Besides a gradient HPLC system for the analysis of the compounds of interest on a LiChrosorb RP-18 (7 microm) column with mobile phase containing 0.05% aq. solution of trifluoroacetic acid and acetonitrile has been elaborated. The procedure has been successfully applied to the analysis of methylxanthines and methyluric acids in urine of patients with chronic asthma treated with theophylline and in urine of healthy subjects.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Caffeine, SAJ special grade, ≥98.5%
Supelco
Caffeine, Pharmaceutical Secondary Standard; Certified Reference Material
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Mettler-Toledo Calibration substance ME 18872, Caffeine, analytical standard, for the calibration of the thermosystem 900, traceable to primary standards (LGC)
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Caffeine, certified reference material, TraceCERT®
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Caffeine, meets USP testing specifications, anhydrous
Sigma-Aldrich
Caffeine, Sigma Reference Standard, vial of 250 mg
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Caffeine, anhydrous, 99%, FCC, FG
Caffeine, European Pharmacopoeia (EP) Reference Standard
Supelco
Caffeine solution, analytical standard, 1.0 mg/mL in methanol
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Melting point standard 235-237°C, analytical standard
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Caffeine solution, 1.0 mg/mL in methanol, ampule of 1 mL, certified reference material, Cerilliant®
Caffeine for system suitability, European Pharmacopoeia (EP) Reference Standard