title: Sensitive determination of D-carnitine as enantiomeric impurity of levo-carnitine in pharmaceutical formulations by capillary electrophoresis-tandem mass spectrometry.
abstract: In this work, capillary electrophoresis-electrospray ionization-tandem mass spectrometry was applied to the determination of l- and d-carnitine in pharmaceutical formulations. A simple sample treatment procedure consisting of the use of a dilution or an extraction step with water was employed prior to derivatization with 9-fluorenylmethoxycarbonyl (FMOC). The method was validated in terms of selectivity, linearity, accuracy, precision and sensitivity, with a LOD of 10ngmL(-1) for each enantiomer, which was enough to detect enantiomeric impurities up to 0.002% of d-carnitine with respect to the main enantiomer (l-carnitine). Eleven pharmaceutical formulations were analyzed including ampoules, oral solutions, sachets, and tablets. Results showed contents for carnitine comprised between 77 and 101% with respect to the labeled ones in the case of those formulations marketed with the racemate, and from 97 to 102% in those cases where the single enantiomer (l-carnitine) was employed as active ingredient. Percentages for the enantiomeric impurity (d-carnitine) ranging from 0.6 to 1.3% were obtained exceeding the limits established for impurities in drug products. These results corroborate the need of validated analytical methodologies enabling the quality control of pharmaceutical formulations containing carnitine.
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, University of Alcalá. Ctra. Madrid-Barcelona Km. 33.600, 28871 Alcalá de Henares, Madrid, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Sánchez-Hernández
authors.forename: Carmen
authors.initials: C
authors.lastname: García-Ruiz
authors.forename: Antonio L
authors.initials: AL
authors.lastname: Crego
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Marina
mesh_terms: D002331:Carnitine / Q000032:analysis* / Q000737:chemistry*; D002626:Chemistry, Pharmaceutical / Q000592:standards; D004340:Drug Contamination; D019075:Electrophoresis, Capillary / Q000379:methods / Q000592:standards; D012680:Sensitivity and Specificity; D013237:Stereoisomerism; D053719:Tandem Mass Spectrometry / Q000379:methods / Q000592:standards*
chemical_list: D002331:Carnitine