title: O-trimethylsilylquinoxalinol derivatives of aromatic alpha-keto acids. Mass spectra and quantitative gas chromatography.
abstract: As an extension of earlier work on aliphatic alpha-keto acids, a method is described for the quantitative gas chromatographic determination of urinary aromatic alpha-keto acids. The keto acids are derivatized with o-phenylenediamine to yield the quinoxalinols. These compounds are chromatographed after trimethylsilylation. The aromatic keto acids are stabilized by sodium dithionite (4 mg/ml urine) and storage below 0 degrees. The final derivatives are stable for weeks at room temperature. Low resolution mass spectra are reported. The fragmentation mechanisms are elucidated by analysis of O-trimethylsilyl-(TMS)-quinoxalinois, O-(TMS-d9)-quinoxalinois and O-TMS-6(7)-chloroquinoxalinois.
mesh_terms: D000328:Adult; D002849:Chromatography, Gas; D006801:Humans; D007202:Indicators and Reagents; D008607:Intellectual Disability / Q000652:urine; D007651:Keto Acids / Q000652:urine*; D008297:Male; D013058:Mass Spectrometry; D010655:Phenylenediamines; D011810:Quinoxalines; D014297:Trimethylsilyl Compounds
chemical_list: D007202:Indicators and Reagents; D007651:Keto Acids; D010655:Phenylenediamines; D011810:Quinoxalines; D014297:Trimethylsilyl Compounds