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Determination of uracil and thymine and their nucleosides and nucleotides in picomole amounts by gas chromatography mass spectrometry selected ion monitoring
Author(s) -
Finn C.,
Schwandt H.J.,
Sadée W.
Publication year - 1979
Publication title -
biomedical mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0306-042X
DOI - 10.1002/bms.1200060505
Subject(s) - chemistry , thymine , isotope dilution , mass spectrometry , chromatography , uracil , selected ion monitoring , nucleotide , ion , dilution , gas chromatography–mass spectrometry , gas chromatography , extraction (chemistry) , dna , biochemistry , organic chemistry , physics , gene , thermodynamics
A stable isotope dilution method is presented by which uracil (Ura) and thymine (Thy) can be determined with high precision and sensitivity at the picomole level utilizing stable isotope dilution and gas chromatography electron impact mass spectrometry in the selected ion monitoring mode. [ 15 N 2 ]Ura and [ 2 H 3 ]Thy served as internal standards. The molecular ions as well as the [M ‐ CH 3 ] + ion fragments of silylated Ura and Thy (Ura‐TMS and Thy‐TMS) were suitable for the assay which provides evidence of specificity, if identical results are obtained at both ions. Nucleosides and nucleotides of Ura and Thy were determined following quantitative hydrolysis in 6 N HCI at 180°C for two hours. Other hydrolsis procedures did not give satisfactory results. Levels of free Ura and Thy were measured in human and rat plasma after solvent extraction with a sensitivity of 20–40 pm ml −1 demonstrating ready applicability of the assay method to biological samples. The potential physiological role of circulating Ura and Thy is discussed.