Gas-chromatographic determination of methylmalonic acid in urine and serum.

We describe a gas-chromatographic procedure for determining methylmalonic acid in serum and urine. The sample is acidified and the compound is extracted from it with diethyl ether, derivatized with N,Obis(trimethylsilyl)trifluoroacetamide, and gas chromatographed. Precision and sensitivity of the method were verified by recovery studies and by comparing the resultswith those foran established procedure in which ion-exchange column chromatography and colorimetry are used. We analyzed biological fluids from normal individuals and from a patient with methylmalonic aciduria to show that the procedure can be applied to diagnosis of disorders that result in abnormally large amounts of methylmalonic acid in urine and serum.