Affiliation:
1. Department of Clinical Pharmacology, University of Umeå, Umeå, Sweden
2. SeQuant AB, Umeå, Sweden
Abstract
Abstract
Background: Measurement of methylmalonic acid (MMA) in serum or plasma is useful for diagnosing cobalamin deficiency. We developed a method for quantifying MMA in plasma based on hydrophilic interaction liquid chromatography (HILIC) and single-stage negative electrospray ionization (ESI) mass spectrometry.
Methods: We deproteinized plasma samples (200 μL) with 800 μL acidified acetonitrile containing 0.17 μmol/L deuterated MMA (D3-MMA) internal standard, centrifuged the samples, and injected 4 μL of the supernatant into the LC-MS instrument. Separation was achieved within 3 min on a Merck SeQuant ZIC®-HILIC column with a mobile phase consisting of 4 volumes acetonitrile plus 1 volume 100 mmol/L ammonium acetate buffer, pH 4.5, at a flow rate of 400 μL/min. Subsequent column washing and reconditioning contributed to a total run time of 10 min. MMA and D3-MMA were quantified by single-ion monitoring (m/z 117.2 and 120.2, respectively) in negative ESI mode at a drying-gas flow rate of 10 L/min, 300 °C, and a capillary voltage of 3.0 kV.
Results: The estimated limits of MMA quantification and detection were 0.09 μmol/L and 0.03 μmol/L, respectively, in plasma. The assay was linear to 200 μmol/L. Interassay and intraassay CVs were ≤5% at all tested concentrations. Recoveries were 90%–93%.
Conclusions: This robust assay allows analysis of MMA in human plasma without derivatization. Sample preparation is simple and suitable for automation.
Publisher
Oxford University Press (OUP)
Subject
Biochemistry, medical,Clinical Biochemistry
Cited by
46 articles.
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