title: Quantitation of tryptophan, kynurenine and kynurenic acid in human plasma by capillary liquid chromatography-electrospray ionization tandem mass spectrometry.
abstract: Concentrations of tryptophan and its metabolites in plasma are of great interest in determining proper diagnosis and medication of several neurological diseases like, for example, Alzheimer's disease. A method of standard addition was developed to determine total level of tryptophan and two of its metabolites, kynurenine and kynurenic acid, in human plasma by capillary liquid chromatography-electrospray ionization tandem mass spectrometry. Plasma samples were simply deproteinized by addition of diluted perchloric acid. Samples were then mixed with trichloroacetic acid and injected onto a capillary column. Analytes were separated by a fast gradient elution of the injected samples. Detection was performed by sheathless electrospray tandem mass spectrometry in the multiple reaction monitoring mode. Linear calibration curves were obtained for spiked plasma sample with up to 100% of the expected analytes concentrations. The determined concentrations were well within ranges previously reported (i.e., 6 nM-95 microM) and limit of detections were around 3 nM for each analyte.
authors.affiliation: Institute of Chemistry, Department of Analytical Chemistry, Uppsala University, PO Box 531, SE-75121 Uppsala, Sweden.
authors.forename: Ardeshir
authors.initials: A
authors.lastname: Amirkhani
authors.forename: Eva
authors.initials: E
authors.lastname: Heldin
authors.forename: Karin E
authors.initials: KE
authors.lastname: Markides
authors.forename: Jonas
authors.initials: J
authors.lastname: Bergquist
mesh_terms: D002138:Calibration; D002853:Chromatography, Liquid / Q000379:methods*; D006801:Humans; D007736:Kynurenic Acid / Q000097:blood*; D007737:Kynurenine / Q000097:blood*; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D014364:Tryptophan / Q000097:blood*
chemical_list: D007737:Kynurenine; D014364:Tryptophan; D007736:Kynurenic Acid