The methods developed were validated with respect to accuracy, precision, linearity, selectivity, sensitivity, limit of detection, and limit of quantification according to the International Conference of Harmonization (ICH) guidelines for validation of analytical procedures. Different variables affecting the reactions between the NQS and the drug bearing amine group such as pH, concentration of NQS, temperature, and reaction time were carefully studied and optimized. The proposed methods were successfully applied to the determination of each... Simple, fast and reliable spectrophotometric methods were developed and validated for the determination of various pharmaceuticals bearing amine group ,cephalosporin, fluoroquinolones, cardiovascular drugs and antimalarial. This book demonstrates the potential of 1,2-Naphthoquinone-4-sulphonic acid sodium salt (NQS) as an analytical reagent for the analysis of pharmaceutical drugs bearing amine group in their pharmaceutical formulation.