ABSTRACT
A spectrophotometric method for the determination of acetylcysteine, captopril carbimazole propylthiouracel and thiopental sodium is described. The method was based on the oxidation of the studied drugs with excess ammonium cerium [IV] sulfate. Followed by measuring the excess unreacted ammonium cerium [IV] sulfate, through reaction with p-DMAB into the corresponding p-dimethylaminobenzoquinone, which has a red colour can be measured at 464 nm. The decrease in the absorption intensity at 464 nm caused by the presence of the investigated drugs is directly proportional to their concentration. Investigations were carried out to study all variables and a validation study for the proposed procedure according to USP 2002 was also performed. Beer's law was obeyed in the range of 1-40 micro.g/ml. The detection limit ranged from 0.22-1.22 micro g/ml, while the quantitation limit ranged from 0.73-4.06 micro g/ml. The proposed method was successfully applied for the analysis of the studied drugs in pharmaceutical preparations with good recoveries in the range of 98.12-100.02%. Results were compared with those obtained from the pharmacopoeial or reported methods