Methylmalonic Acid (MMA), Amniotic Fluid
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 micro) 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 to 73 m/z and 120 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 M, Matern J: Methylmalonic acid quantitation in serum, urine and amniotic fluid: A method modification with benefits. J Am Soc Mass Spec 2010;21:Supplement 1. S44)
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
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test