The use of deuterium oxide as a mobile phase for structural elucidation byHPLC/UV/ESI/MS

The use of deuterium oxide as a mobile phase in the routine analysis of pha rmaceutical compounds was investigated. The deuterium exchange of labile hy drogen atoms aids in structural confirmation and elucidation of unknown imp urities and degradation products. Although deuterium oxide as a mobile phas e does in some cases change the retention times, the changes in retention t imes do not interfere with the analysis. A study of the highperformance liq uid chromatography system shows that equilibration times for the deuterium- containing mobile phases are similar to equilibration times with changes of other mobile phases. The use of this technique in the analysis of pharmace utical compounds and other small molecules is presented.