Methylmalonic Acid (MMA), Quantitative, Serum
Method Description Describes how the test is performed and provides a method-specific reference
Methylmalonic acid (MMA) is determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS) stable isotope dilution analysis. The specimen is mixed with an internal standard (methyl-d3-malonic acid; d3-MMA, 0.2 nmol). MMA and d3-MMA are isolated by automated strong anion-exchange solid phase extraction. LC-MS/MS is performed using mobile phases composed of acetonitrile/0.4% aqueous formic acid and water/0.4% aqueous formic acid (5/95, v:v) using a short C18 column (C18, 50 mm x 4.6 mm, 5 micron) to separate MMA and d3-MMA from the bulk of the specimen matrix. The MS/MS is operated in the multiple reaction monitoring (MRM) negative mode to follow the precursor to product species transitions 117 m/z to 73 m/z and 120 m/z to 76 m/z for MMA and d3-MMA respectively. Separation of MMA/d3-MMA from the more physiologically abundant succinic acid is accomplished by the careful selection of MRM transitions and optimization of the LC separation. The ratios of the extracted peak areas of MMA to d3-MMA determined by LC-MS/MS are used to calculate the concentration of MMA present in the sample.(Lacey J, Magera MJ, Matern M: Methylmalonic acid quantitation in serum, urine and amniotic fluid: a method modification with benefits. J Am Soc Mass Spec 2010:21, Supplement 1, S44)
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Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Friday; Continuous until noon