| Rapid determination of C4-acylcarnitine and C5-acylcarnitine isomers in plasma and dried blood spots by UPLC-MS/MS as a second tier test following flow-injection MS/MS acylcarnitine profile analysis. | |
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MedLine Citation:
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PMID: 20591710 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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BACKGROUND: Flow-injection MS/MS methods for elevated acylcarnitines are routinely performed in most newborn screening and biochemical genetics laboratories; however this technique cannot distinguish between isobaric compounds; therefore, chromatographic separation is required to quantitate isomers for differential diagnosis of some inborn errors of metabolism. METHODS: A UPLC-MS/MS method has been developed for the simultaneous quantitation of isobutyrylcarnitine and butyrylcarnitine, and a second UPLC-MS/MS method for the quantitation of isovalerylcarnitine, (S) and (R) 2-methylbutyrylcarnitine, pivaloylcarnitine and valerylcarnitine. Plasma and dried blood spots samples are extracted with methanol and derivatized with butanolic HCl. Deuterium labeled internal standards are used for quantitation. Separation is obtained using a methanol/water gradient with a C18 BEH, 1x100mm, 1.7microm UPLC column, at 60 degrees C; run time is less than 10min. The isomers are detected with a Quattro Premier triple quadrupole, with electrospray ionization in positive ion mode. RESULTS: Intra-day precision in plasma and dried blood spots ranged from 1.4% to 14% and accuracy from 88% to 114% respectively for butyrylcarnitine and isobutyrylcarnitine. Precision for the isomers of C5-acylcarnitine ranged from 1.3% to 15% and accuracy 87% to 119%, respectively in plasma or dried blood spots. Inter-day precision was within 20% at each concentration of isobutyrylcarnitine and butyrylcarnitine. Precision for 2-methylbutyrylcarnitine and isovalerylcarnitine at concentrations above the normal range was within 24%. CONCLUSIONS: Two diagnostic tests based on the separation of C4-acylcarnitine and C5-acylcarnitine isomers by UPLC-MS/MS provide fast differential diagnosis of SCAD deficiency versus IBCD deficiency and IVA versus 2-MBCD deficiency. The separation of C5-acylcarnitines can reveal false elevation due to pivalic acid-containing antibiotics. Abnormal newborn screen results due to pivalate-generating prodrug antibiotics of maternal origin were confirmed. This separation of isomers can resolve multiple diagnostic challenges in both newborn screening and in cases with ambiguous metabolic test results. |
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Authors:
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Sabrina Forni; Xiaowei Fu; Susan E Palmer; Lawrence Sweetman |
Publication Detail:
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Type: Journal Article Date: 2010-06-10 |
Journal Detail:
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Title: Molecular genetics and metabolism Volume: 101 ISSN: 1096-7206 ISO Abbreviation: Mol. Genet. Metab. Publication Date: 2010 Sep |
Date Detail:
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Created Date: 2010-08-16 Completed Date: 2011-01-24 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9805456 Medline TA: Mol Genet Metab Country: United States |
Other Details:
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Languages: eng Pagination: 25-32 Citation Subset: IM |
Affiliation:
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Institute of Metabolic Disease, Baylor Research Institute, Dallas, TX 75226, USA. sabrinaf@baylorhealth.edu |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Carnitine
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analogs & derivatives*,
blood,
chemistry Chromatography, Liquid / methods Humans Infant, Newborn Isomerism Neonatal Screening / methods Tandem Mass Spectrometry / methods* |
| Chemical | |
Reg. No./Substance:
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0/acylcarnitine; 25518-49-4/isobutyryl-1-carnitine; 25576-40-3/butyrylcarnitine; 541-15-1/Carnitine; 98299-38-8/pivaloylcarnitine |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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