Introduction
NMR spectroscopy of biofluids, in particular of
urine and bile, has for the last few years proved to
be a useful adjunct to the traditional techniques
for identifying drug metabolites and in combination
with simple solid-phase extraction techniques
for concentrating metabolites, it has proved to be
a general and versatile approach [1]. The methodology
available has been augmented by the use of directly-coupled HPLC-NMR which has been
shown to be a powerful and efficient technique for
separation of mixtures and identification of their
components [2,3]. Applications have included
chemical mixtures [4], natural products [5] and
peptide libraries [6]. However, the methodology
has been used most extensively for the identification
of drug metabolites [7-12] and related model
compounds [13,14].
Although the most sensitive NMR nuclei, ~H
and 19F with spin I= 1/2, have been used so far in
HPLC-NMR, one study has employed 3~p NMR
detection [15] and it should be possible in princi-