Abstract:
Three simple, sensitive and reproducible spectrometric methods for the selective
determination of nalbuphine–HCl in presence of its oxidative degradate were investigated.
The first method depended on the quantitative densitometric evaluation of thin layer
chromatograms of the drug at 284 nm using chloroform–methanol–acetic acid (7:3:0.05
v/v/v) as a mobile phase, in a concentration range of 10-30 μg/spot. The second one used
the pH induced difference absorbance (ΔA) between 0.1M NaOH and 0.1 M HCl drug
solutions at 299 nm to determine 20-160 μg mL-1 of the drug. The third method was a
bivariate calibration algorithm for the determination of nalbuphine–HCl over concentration
range of 20-200 μg mL-1. The proposed methods selectively analysed the drug in
presence of up to 80% of its oxidative degradate with mean recoveries of 100.63±1.03 for
densitometric method and up to 90% with recoveries of 99.97±1.16 and 100.09±1.47%
regarding the two other methods, respectively. The three proposed methods were
successfully applied to analyse nalbuphine– HCl in its preparations, the results obtained
were statistically analysed and found to be in accordance with those given by the
compendial method.
