LIQUID-CHROMATOGRAPHIC ATMOSPHERIC-PRESSURE CHEMICAL-IONIZATION MASS-SPECTROMETRIC ANALYSIS OF GLYCINE CONJUGATES AND URINARY ISOVALERYLGLYCINE IN ISOVALERIC ACIDEMIA

n-Acetylglycine, n-propionylglycine, n-butyrylglycine, isobutyrylglyci ne, n-valerylglycine, isovalerylglycine, heptanoylglycine, phenylacety lglycine and isovalerylglucuronide were identified based on their liqu id chromatographic-atmospheric pressure chemical ionization mass spect ra (LC-APCI-MS). We were able to detect the presence of urinary isoval erylglycine in two cases of isovaleric acidemia using LC-APCI-MS. Memb rane-filtered urine samples were injected into the LC-APCI-MS system i n the negative-ion mode without any further pretreatment, and large am ounts of isovalerylglycine were detected as the [M-H](-) ion. The urin ary excretion of isovalerylglycine appeared to increase after L-carnit ine therapy. This analytical method is quick and easy and it may be a useful tool in understanding dysfunctional conditions in isovaleric ac idemia.