Mass spectrometry of nucleotides: VII. Identification of nucleoside phosphite esters by pyrolysis electron impact and field desorption mass spectrometry

• Published in: Journal of analytical and applied pyrolysis 1983, Vol.5 (3), p.173-182
• Main Authors: Schiebel, H.-M., Schulten, H.-R.
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Chemistry; Exact sciences and technology; Spectrometric and optical methods
• ISSN: 0165-2370; 1873-250X
• DOI: 10.1016/0165-2370(83)80026-6

Pyrolysis electron impact mass spectrometry was employed for the identification of nucleoside phosphites which are commonly used for oligonucleotide synthesis according to the phosphite approach. Characteristic fractions of the pyrolysis products were recorded using repetitive magnetic scans during programmed temperature rise. The results clearly demonstrate the applicability of this method for a rapid characterization of these building blocks. Fractionated pyrolysis of the thermally lablie nucleoside phosphites gave less complex spectra than those for the analogous, more stable, nucleoside phosphate triesters. Thus, the three characteristic structural units of the nucleoside phosphites, i.e. the phosphite moiety, the protecting dimethoxytrityl group and the nucleobase, can be thermally eliminated and detected in distinct steps. Field desorption mass spectrometry enables the direct determination of the molecular weights of the nucleoside phosphites and hence can be utilized as a complementary analytical tool. In addition purity control is easily performed and an indication can be obtained as to the by-products.