Investigation of the feasibility of directly-coupled HPLC-NMR with H-2 detection with application to the metabolism of N-dimethylformamide-d(7)

The use of H-2 NMR spectroscopy as a detector for HPLC has been investigated using the continuous flow method in which rat urine containing metabolites of N-dimethylformamide-d(7) was employed as a test case. Three xenobiotic-related species, including DMF-d(7) itself, were detected. It is shown that for small molecules which give relatively sharp H-2 NMR resonances, H-2 HPLC-NMR spectroscopy is a feasible technique. For larger molecules, the resulting broad fines are likely to preclude the determination of detailed structural information. However, extension of the approach is possible by the use of selectively H-2-labelled xenobiotics to determine HPLC retention times of metabolites with continuous-flow H-2 NMR spectroscopy detection, followed by stop-flow H-1 HPLC-NMR spectroscopy for structural characterisation. (C) 1997 Elsevier Science B.V.