A comparison of capillary‐scale LC–NMR with alternative techniques: spectroscopic and practical considerations

Abstract

Experimental and practical details for the use of capillary LC (CapLC)-NMR are reported. The capillary NMR probe has high sensitivity and excellent flow characteristics and we found CapLC-NMR to be best suited to samples that are truly mass limited. CapLC-NMR relies on good capillary-scale chromatography where highly concentrated peaks with a volume closely matched to the NMR flow cell are achievable. Provided that the loading capacity of the capillary column is not limiting, the combination of high sensitivity and high solvent suppression quality makes CapLC-NMR an excellent choice. For many real samples, however, the loading is limiting and we found the combination of LC-SPE-MS-NMR with a cryoprobe enables more material to be purified for NMR analysis, while retaining sensitivity.

A Historical Overview of Natural Products in Drug Discovery

“…The application of HPLC-NMR to the crude extracts (NMR and UV profile from PDA HPLC detection) was found to be a powerful spectroscopic tool which had advanced in the last decade, in particular with the advent of higher field magnets and cryo-probes. In recent years the advances in microcoil HPLC-NMR and capillary NMR (CapNMR) has allowed for smaller quantities of samples to be analyzed in the order of 40–120 µL, this in combination with higher field magnets has greatly increased the sensitivity in profiling and dereplication natural product extracts [138,139,140]. Microcoil HPLC-NMR is generally suited for on-line HPLC-NMR typically where components present in higher concentrations in an extract are separated and analyzed in a conventional HPLC-NMR system using either on-flow, stop-flow or time slicing experiments [103,141,142,143].…”

Which Hydroxy? Evidence for Species Differences in the Regioselectivity of Glucuronidation in Rat, Dog, and Human in Vitro Systems and Dog in Vivo

“…Recent advances in NMR technology (Bernstein and Lewis, 2004), such as capillary NMR (Lewis et al, 2005) and HPLC-solid-phase extraction-NMR (Sandvoss et al, 2005), have brought improvements to sensitivity in metabolite identification. Despite this, much metabolite identification work is performed close to the sensitivity limits, and it is often only feasible to obtain proton NMR spectra or simple proton-proton correlations within a reasonable time frame.…”

The study of amino acid composition of sapropel by the capillary electrophoresis method

“…Traditionally, capillary electrophoresis is compared with high performance liquid chromatography since in both methods separation takes place in a confined space (capillary or column) involving the mobile liquid phase (buffer or eluent), and for registration of signals the similar principles for detection and software data processing are applied [5,9,10].…”