A comparison of capillary-scale LC-NMR with alternative techniques: spectroscopic and practical considerations.

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.