Liquid chromatography-mass spectrometry using the hydrogen/deuterium exchange reaction as a tool for impurity identification in pharmaceutical process development

HPLC-MS employing deuterium oxide and common MS-compatible deuterated additives in the mobile phase with electrospray ionization is shown to be a viable approach for the structural elucidation of impurities in pharmaceutically active agents following initial studies with protic mobile phases. This approach incorporates the hydrogen/deuterium (H/D) exchange reaction where deuterium is substituted for hydrogen at labile sites. Some developmental compounds studied include an amide, amine, lipopeptide, indole and methyl sulfone. H/D exchange is rapid and the chromatographic performance using deuterated mobile phases is comparable to protic counterparts.