INTRODUCTION OF DEUTERIUM BY EXCHANGE FOR MEASUREMENT BY MASS-SPECTROMETRY

This chapter gives an introduction of deuterium by exchange for measurement by mass spectrometry. The chemical incorporation of deuterium followed by measurement of the intact product by mass spectrometry has for a number of years played a major role in three, often overlapping areas: the structural characterization of molecules of unknown structure; to gain information on the mechanisms of chemical or biological reactions; and as an aid in the interpretation of mass spectra. Although microscale deuterium exchange procedures are experimentally simple, they suffer from the principal disadvantage of ease of reexchange, which can occur readily because of adsorbed protium (water) on glassware or mass spectrometer surfaces, or in solvents or air. Compared with incorporation and measurement of nonactive deuterium or of other isotopes, sample handling and introduction into the mass spectrometer is usually a critical experimental issue. Primarily because of re-exchange, mass spectrometric methods employing thermal vaporization are generally limited to compounds having 4-6 exchangeable hydrogens, while with ion desorption methods which use deuterated matrix, the useful range may be extended to compounds having over 20 active hydrogen atoms. © 1990, Elsevier Inc. All rights reserved.