Optimization and performance of a rapid gas chromatography-mass spectrometry analysis for methylmalonic acid determination in serum and plasma

We have developed a rapid and sensitive GC-MS assay for methylmalonic acid determination in serum and plasma utilizing an anion exchange solid-phase extraction and trimethylsilyl derivatization. Each step of the procedure was optimized by the experimental design methods to assure the assay reliable performance. The limit of detection and limit of quantitation were 0.075 and 0.1 mu mol/l. The total coefficient of variation for the method was 9.8, 4.4, and 4.6% at the concentration of 0.2, 3.1, and 6.2 mu mol/l methylmalonic acid concentration, respectively. The assay was linear up to 9.0 mu mol/l, and showed good correlation with a reference method. The method has proven to be reliable in routine production, producing clean chromatography, unique ion fragments, and consistent ion mass ratio. (C) 2000 Elsevier Science B.V. All rights reserved.