Development of Colorimetric Method for the Assay of N-acetylcysteine in Dosage Forms using 2, 6-Dichloroquinone-4-Chlorimide

ABSTRACT A simple colorimetric method was developed for the determination of N-acetylcysteine (NAC) in pharmaceutical preparations. The method is based on the coupling N-acetylcysteine with 2,6-dichloroquinone-4-chlorimide (DCQ) in dimethylsulphoxide to give a yellow colored product absorbing at 438 nm. The absorbance-concentration plot was rectilinear over the range of 10-50 μg/mL with minimum detection limit (LOD) of 0.769 μg/mL .The recovery results (100.90 ± 0.00%, n=3) reflected no interference by the formulation excipients. The different experimental parameters affecting the development and stability of the color were carefully studied and optimized. The developed method was successfully applied to the analysis of NAC in injection and capsule dosage forms. The results obtained were statistically compared with those of the official titrimetric methods. A pathway for the reaction of NAC with DCQ was suggested