title: Separation and identification of underivatized plasma acylcarnitine isomers using liquid chromatography-tandem mass spectrometry for the differential diagnosis of organic acidemias and fatty acid oxidation defects.
abstract: A simple HPLC-MS/MS method has been established to separate and identify underivatized acylcarnitine isomers. Human plasma samples were deproteinized and concentrated. Acylcarnitines were separated on a reverse phase column and detected with triple quadrupole linear ion trap mass spectrometry. Deuterium-labeled internal standards were used for quantitation. To identify acylcarnitines without pure standards, information-dependent acquisition linking to enhanced product ion scan mode was used. 112 acylcarnitines, including stereoisomers, were found in samples of patients. Dicarboxylic acylcarnitines, such as methylmalonylcarnitine and glutarylcarnitine, were detected with high sensitivity. Three stereoisomers of (R,S)2-methyl-3-hydroxy butyrylcarnitine were detected in samples of patients with β-ketothiolase deficiency. Validation results revealed excellent precision and accuracy of the method. In general the within- and between-run coefficients of variation (CV%) were less than 15%, and recoveries were in the range of 92.7-117.5%. In addition, the reference intervals of acylcarnitines for children aged 3-day to13-year old were established. Using the new method and reference intervals, we have correctly diagnosed 49 patients with fatty acid oxidation defects or organic acidemias in 176 high-risk patients.
authors.affiliation: The Laboratory of Endocrinology and Metabolism, Guangzhou Women and Children's Medical Center, 9 Jinsui Road, Guangzhou, China.
authors.forename: Minzhi
authors.initials: M
authors.lastname: Peng
authors.forename: Xiefan
authors.initials: X
authors.lastname: Fang
authors.forename: Yonglan
authors.initials: Y
authors.lastname: Huang
authors.forename: Yanna
authors.initials: Y
authors.lastname: Cai
authors.forename: Cuili
authors.initials: C
authors.lastname: Liang
authors.forename: Ruizhu
authors.initials: R
authors.lastname: Lin
authors.forename: Li
authors.initials: L
authors.lastname: Liu
mesh_terms: D002331:Carnitine / Q000031:analogs & derivatives* / Q000097:blood; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003937:Diagnosis, Differential; D005227:Fatty Acids / Q000378:metabolism*; D006801:Humans; D007536:Isomerism; D008661:Metabolism, Inborn Errors / Q000175:diagnosis*; D010084:Oxidation-Reduction; D012015:Reference Standards; D015203:Reproducibility of Results; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D005227:Fatty Acids; C116917:acylcarnitine; D002331:Carnitine
keywords: Acylcarnitine; LC–MS/MS; Plasma; Product ion spectrum; Stereoisomer