Gas Chromatographic-MassSpectrometricIdentificationof Isosaccharino- 1,4-Iactone in HumanSerum and Urine

We have identified a-isosaccharino-1 ,4.-Iactone and (.isosaccharino-1 ,4-Iactone in the ethyl acetate extract of an ultrafiltrate of blood and of normal human urine, using high-resolution gas chromatography-mass spectrometry. The ultrafiltrate of blood was obtained from three patients on hemodialysis, one with psoriasis vulgaris, one with uremia, and one with amyotrophic lateral sclerosis. The concentration of f3-isosaccharino1,4-lactone in the ultrafiltrate was twoto threefold that of a-isosaccharino1,4-lactone. Mass fragmentography showed that isosaccharino1,4-lactone is normally present in human serum in a concentration of 1.7 (SD 1.5) mg/L. In physiological fluid, isosaccharino-1 ,4-Iactone apparently is present in its hydrated form, isosaccharinate.