title: Simultaneous quantification of caffeine and its three primary metabolites in rat plasma by liquid chromatography-tandem mass spectrometry.
abstract: A rapid, sensitive, simple and accurate LC-MS/MS method for the simultaneous quantitation of caffeine, and its three primary metabolites, theobromine, paraxanthine, and theophylline, in rat plasma was developed and validated. Chromatographic separation was performed on an Agilent Poroshell 120 EC-C18 column using 1 μg/mL acetaminophen as an internal standard. Each sample was run at 0.5 mL/min for a total run time of 7 min/sample. Detection and quantification were performed using a mass spectrometer in selected reaction-monitoring mode with positive electrospray ionization. The lower limit of quantification was 5 ng/mL for all analytes with linear ranges up to 5000 ng/mL for caffeine and 1000 ng/mL for its metabolites. The coefficient of variation for assay precision was less than 12.6%, with an accuracy of 93.5-114%. The assay was successfully applied to determine plasma concentrations of caffeine, theobromine, paraxanthine, and theophylline in rat administered various energy drinks containing the same caffeine content. Various energy drinks exhibited considerable variability in the pharmacokinetic profiles of caffeine and its three primary metabolites, even containing the same caffeine. Different additives of energy drinks might contribute to these results.
authors.affiliation: College of Pharmacy, The Catholic University of Korea, Bucheon, Gyeonggi-do 420-743, Republic of Korea.
authors.forename: Eu Jin
authors.initials: EJ
authors.lastname: Choi
authors.forename: Soo Hyeon
authors.initials: SH
authors.lastname: Bae
authors.forename: Jung Bae
authors.initials: JB
authors.lastname: Park
authors.forename: Min Jo
authors.initials: MJ
authors.lastname: Kwon
authors.forename: Su Min
authors.initials: SM
authors.lastname: Jang
authors.forename: Yu Fen
authors.initials: YF
authors.lastname: Zheng
authors.forename: Young Sun
authors.initials: YS
authors.lastname: Lee
authors.forename: Su-Jun
authors.initials: SJ
authors.lastname: Lee
authors.forename: Soo Kyung
authors.initials: SK
authors.lastname: Bae
mesh_terms: D000818:Animals; D002110:Caffeine / Q000097:blood* / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013805:Theobromine / Q000097:blood; D013806:Theophylline / Q000097:blood
chemical_list: D002110:Caffeine; D013806:Theophylline; D013805:Theobromine; C021183:1,7-dimethylxanthine
keywords: Caffeine; Energy drinks; Liquid chromatography–tandem mass spectrometry; Paraxanthine; Rat plasma; Theobromine; Theophylline