ABSTRACT
This chapter presents a historical review of sample flow and nuclear magnetic resonance (NMR) spectroscopy. Descriptions of setting up the liquid chromatography (LC)–NMR system for continuous-flow mode versus the direct stopped-flow mode are provided. The basic equipment added to an NMR spectrometer for a stopped-flow NMR experiment is outlined, which includes a controlling station with chromatography software, a high-performance liquid chromatography (HPLC) system controlled by chromatography software, an LC-NMR flow probe and a Peak router (sampling unit for multiple collections and various storage modes). Calibration of LC-NMR system parameters is described. These parameters include time/volumes required to position the sample during an LC-NMR measurement. Solid-phase extraction (SPE) is presented, which includes optimal sample addition to a cartridge.
Solvent requirements in LC-NMR and associated costs using deuterated solvents are discussed. Other topics include referencing, the effects of diffusion on the lineshape of a compound’s resonances, and the challenges of shimming and locking a sample in a continuous-flow solvent-gradient LC-NMR environment. Considerations for conducting continuous-flow experiments are also discussed, including sources of error for measuring chemical shifts.
