Rapid Underivatized Method for Quantitative Methylmalonic Acid by Liquid Chromatography-Tandem Mass Spectrometry.

Background: Increased methylmalonic acid (MMA) levels can aid in assessing vitamin B12 deficiency or abnormal propionate metabolism. MMA analysis by LC-MS/MS is challenging because of both the nanomolar reference range and potential interference from succinic acid, an endogenous isomer. We show that ultrafiltration followed by gradient chromatography permits rapid, sensitive, and selective quantification that is essentially devoid of matrix effects.