Bilirubin interference in kinetic creatinine determination.

194 CLINICAL CHEMISTRY, Vol. 25, No. 1, 1979 gas chromatography before and after acid (6 mol/L HC1) and alkaline (NaOH) hydrolysis. We frequently observe a peak in the lactic acid position after alkaline hydrolysis. After acid hydrolysis of the same urine no lactate isobserved, but a peak appears in the position of levulinic acid. The mass spectra of these two peaks were identical with those of authentic lactic and levulinic acids, respectively. On hydrolysis of urine from diabetic patients, the lactate and levulinate increased by 30 to 50 times normal. We thought that these acids were formed from glucose by degradative reactions, and confirmed this by hydrolysis of a 10 g/L solution of glucose under acid and alkaline conditions. Again, levulinic and lactic acids respectively, were found by gas chromatographymass spectrometry. Levulinic acid is not a normal constituent of human urine (6) but has been reported to be present after medication