Simplified Analysis of Mixtures of Small Molecules by Chromatographic NMR Spectroscopy

摘要

The determination of the components of assemblies of small molecules is an extremely common task in chemical laboratories, and HPLC is the preferred technique for separation and analysis of complex mixtures. A wide variety of sophisticated functionalized chromatographic solid supports has been developed (octadecylsilyl (ODS), cyano, amino) and adapted to different analytical problems. Recently, we introduced an alternative for the identification of the components in a mixture, without any chromatography involved, by using solid-enhanced diffusion-based NMR spectroscopy.[1], [2] The method mimics a part of the chromatographic process in that the molecular average mobilities in the mixture are modified according to the individual affinities for the stationary phase. This enhances the spectral-separation capabilities of diffusion-based pulsed field gradient (PFG) experiments, such as DOSY.[3] Herein we show that, at least in favorable cases, this technique can provide a simpler approach to mixture analysis, yielding separation of the spectral components by using simple solid supports, such as regular porous silica gels.