Ba. Dawson et Db. Black, UTILIZING NUCLEAR-MAGNETIC-RESONANCE (NMR) SPECTROSCOPY FOR ASSESSINGNADOLOL RACEMATE COMPOSITION, Journal of pharmaceutical and biomedical analysis, 13(1), 1995, pp. 39-44
NMR methods were developed for the determination of the racemate compo
sition in nadolol racy materials. With high-field instruments (400 MHz
or greater) the racemate ratio may be determined by the relative heig
hts of the t-butyl peaks, which are well enough resolved for this dete
rmination. For lower field spectrometers, the t-butyl peaks are not re
solved. An NMR method has been developed which involves preparation of
the tribenzoate derivative of the drug. Seven lots of nadolol raw mat
erial, as well as several standards, were analysed for their racemate
content. Three lots of raw material did not meet the USP limits of 40-
60% for racemate A. Of these, two were granular in appearance and were
found to vary markedly in racemate composition in successive analyses
. The results for all the materials of uniform content agree Very well
with those from the HPLC method, as well as for the USP IR method usi
ng the absorbance at the corrected wavelength.