Colorimetric determination of D-Penicillamine in bulk form and in capsules using 4-Chloro-7-nitrobenzofuran

ABSTRACT

A simple and selective colorimetric method for the quantification of D-penicillamine in the presence of some penicillin preparations, common penicillin degradation products, EDTA and vitamin C is described. The method is based on the interaction between D-penicillamine in aqueous solution and 4-chloro-7-nitro-benzofurazan [NBD-C1], 0.1% w/v in methanol, in presence of 0.1 M borax solution. The developed colored product, after dilution with presence of 0.1 M borax solution. The developed colored product, after dilution with acetone, could be measured quantitatively at 612 nm. All variables were studied to optimize the reaction conditions. Regression analysis of Beer's plot showed good correlation [r=0.9990] in a general concentration range of 4-20 micro g ml-1 with a detection limit of 0.078, which represent the minimum absorbance value that can be measured. No interference could be observed from the presence of somepenicillins, penicillin degradation products and common pharmaceutical adjuvants. However, benzathine penicillin degradation and Vitamin cinterfere with analysis of the named drug by the proposed method. This method was applied successfully for the analysis of D-penicillamine in bulk from and in capsules. The results obtained are in good agreement with those obtained by the USP XXII method: