Both organic acids and amino acids in urine were analyzed to find the metabolic disorders and the congenital metabolic diseases, as earlier as we can, by the GC-MS-COM screening system which is able to screen many kinds of diseases with one screening, in a small sample, rapidly and exactly. After the simple treatment which means the extraction of acids with diethyl ether at pH1and the elution of amino acids through the AG-50W-X12cation exchange resin, the sample of urine corresponding to5mg of creatinine was subjected, as a fundamental experiment, to the GC-MS-COM system equipped with one2m glass-coiled column packed with3%OV-17. When a patient's urine was analyzed in order of the procedure, a large peak which was not detected in normal urine, was identified as a methylmalonic acid by the analysis of the mass spectrum.
