Nuclear magnetic resonance spectroscopic method for determination of penicillamine in capsules

A rapid and specific nuclear magnetic resonance (NMR) spectroscopic method for the determination of penicillamine in capsules is presented. The sample is directly dissolved in D2O and its spectrum recorded on a 90 MHz instrument. The 2 singlets appearing at 1.58-1.64 ppm, due to the nonequivalent gem-dimethyl groups, were integrated and compared with the integral obtained for the phenyl proton signals of sodium saccharin, which is the internal standard. The results obtained by the proposed method closely agreed with those found by the method of USP XX.