399SPECTROPHOTOMETRIC DETERMINATION OF ANTIPARKINSONIAN DRUG IN CAPSULES AND SPIKED PLASMA USING IRON (III) AND POTASSIUM FERRICYANIDEA simple, accurate, sensitive and economical procedure for the estimation of amantadine HCl (AMD), in both capsules and spiked human plasma has been developed. In the presence of potassium ferricyanide, it has been demonstrated that Fe (III) is reduced to Fe (II) by the studied drug in acidic medium. In addition, soluble Prussian blue (KFe[Fe(CN)6]) was produced by the reaction between the formed Fe (II) and potassium ferricyanide, and the reaction mechanism was discussed. The absorbance of soluble Prussian blue is measured at the absorption maximum of 735 nm. Beer's law is obeyed in the concentration range 0.2-7.8 μg/mL. The molar absorptivity is 2.15 x 104 L/mol.cm. Sandell sensitivity is 8.73 ng/cm2. The limits of detection as well as quantification are reported. Sex replicate analyses (n=6) of solutions containing three different concentrations of AMD was carried out. The percent error and the RSD values have been reported. The proposed method was applied to the determination of AMD in capsules and spiked human plasma and the results demonstrate that the method is equally accurate and precise as the official methods as found from the t- and F-values. The reliability of the method was established by recovery studies using standard-addition technique.hanyomara666@yahoo.comResearch512014Amantadine HCl,Spectrophotometry,Oxidation reaction, Iron (III) chloride,Potassium ferricyanideHany A. OmaraChemistry Department, Faculty of Science, Sirt University, Sirt, Libya.