title: Determination of carnitine and acylcarnitines in plasma by high-performance liquid chromatography/electrospray ionization ion trap tandem mass spectrometry.
abstract: A high-performance liquid chromatography/mass spectrometry method was developed for the determination of carnitine, its biosynthetic precursor butyrobetaine, and eight acylcarnitines in plasma. The procedure includes a solid-phase extraction for carnitine and short- and medium-chain acylcarnitines, and a liquid-liquid extraction for protein-bound long-chain acylcarnitines, followed by separation on a reversed-phase column in the presence of a volatile ion-pairing reagent. Detection was achieved using an ion-trap mass spectrometer run in the tandem mass spectrometry (MS/MS) mode. The choice of the matrix for calibrators, used for quantification of these endogenous compounds, was also investigated. Validation was performed for standard quality controls diluted with 4% bovine serum albumin solution and for spiked plasma quality control samples at concentrations between 0.5 and 80 micromol/L, depending on the compound. Intra- and inter-day precisions for the determination of carnitine were below 3.4% and accuracies were between 95.2 and 109.0%. Application of the method to the diagnosis of pathological acylcarnitine profiles of metabolic disorders in a patient suffering from methylmalonic aciduria is presented. The method allows quantification of carnitine, butyrobetaine, acetylcarnitine and propionylcarnitine, and semiquantitative analysis of medium- and long-chain acylcarnitines. In contrast with other methods, no derivatization step is needed.
authors.affiliation: Division of Clinical Pharmacology & Toxicology, and Department of Research, University Hospital of Basel, Switzerland.
authors.forename: Laurence
authors.initials: L
authors.lastname: Vernez
authors.forename: Markus
authors.initials: M
authors.lastname: Wenk
authors.forename: Stephan
authors.initials: S
authors.lastname: Krähenbühl
mesh_terms: D002138:Calibration; D002331:Carnitine / Q000031:analogs & derivatives* / Q000097:blood* / Q000302:isolation & purification; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D006801:Humans; D008764:Methylmalonic Acid / Q000097:blood; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods
chemical_list: C116917:acylcarnitine; D008764:Methylmalonic Acid; D002331:Carnitine