Identification of two Thormählen-positive compounds from melanotic urine by gas chromatography-mass spectrometry

The isolation of two Thormahlen-positive compounds from the urine of a patient with malignant melanoma and the elucidation of their structure by gas chromatography—mass spectrometry is described. The compounds were isolated using a poly-N-vinylpyrrolidone column and separated by preparative thin-layer chromatography. After elution they were analyzed by gas chromatography and gas chromatography—mass spectrometry as their trimethylsilyl derivatives and after hydrolysis also as their tert.-butyldimethylsilyl derivatives. The results showed the main Thormahlen-positive compound A to be the glucuronide of 5-hydroxy-6-methoxyindole, whereas the minor compound AX appeared to be the glucuronide of its isomer 6-hydroxy-5-methoxyindole.