DEUTERIUM-OXIDE AS A REAGENT FOR THE MODIFICATION OF MASS-SPECTRA IN ELECTROSPRAY MICROCOLUMN LIQUID-CHROMATOGRAPHY MASS-SPECTROMETRY

Microcolumn liquid chromatography was used in combination with a quadrupole mass spectrometer equipped with an electrospray ionization interface. Deuterium oxide was used as a reagent to induce peak shifts in mass spectra. The peak shift obtained gives the number of heteroatoms carrying hydrogen atoms that are present in a molecule. Examples relating to amino alcohols, peptides and sugars are given. Two different modes of operation were investigated; postcolumn addition of the reagent to the eluent from the column and the use of deuterium oxide as a mobile phase component. The latter technique makes use of a dynamic exchange reaction on-column. Exchanged hydrogen atoms are carried away from the migrating zone (as H2HO or H2O) containing the target compound, leading to a high yield of the deuterated compound. On-column exchange was found to be more useful, especially if the compounds contained several exchangeable hydrogen atoms. No significant changes were observed with regard to chromatographic selectivity or efficiency