Steps to improve the sensitivity of NMR analysis are being investigated. The amount of analyte present, enrichment in 2H and 13C, NMR sensitivity for both nuclei, magnetic field, and time on the spectrometer are more or less fixed. Improvements can be made by increasing the analyte mass (urine glucuronides provide more hexose than a few mL of blood) or pooling experimental animals, but there are limits.
Instead, the focus has been on the NMR probe, sample volumes and concentration. Custom- designed 3 mm probes are proving much superior to the standard 5 mm probes for 2H NMR. We are exploring the use of very small sample volumes and susceptibility-matched sample tubes to improve sensitivity further.