Abstract
The electrochemical oxidation and reduction behaviour of adsorbed species of antimetabolic antineoplastic agent Tarabine PFS (Cytosar-U) in Sorensen buffer solution of different pH values at an in situ-mercury film electrode (MFE) is studied using cyclic voltammetry (CV) and Osteryoung square-wave stripping voltammetry (OSWSV). Optimal experimental and operational parameters have been selected for the drug preconcentration and determination in aqueous medium. Based on the adsorption and accumulation of Tarabine PFS using Osteryoung square-wave anodic stripping voltammetry (OSWASV) at MFE, the drug is easily detected as 0.134ng/ml (5.51×10−10M). Calibration plots have been constructed at different accumulation times. The standard deviation (n=10) at a concentration level of 6×10−8M Tarabine PFS is 0.062. The interaction of ssDNA with the drug under the optimal conditions at pH 7.7 has been studied. The formal potentials E° and E°′ and the equilibrium constants K1 and K2 have been calculated for the free form of Tarabine PFS and the bonded form with ssDNA, respectively. It was found that K2 value for the bonded oxidized form is 298 times than that of K1 for the bonded reduced form. Therefore, ssDNA has been found to interact strongly with the oxidized form of the drug. The method has been used for the nanogram determination of ssDNA with 1.9% variation coefficient. Detection limit of 3ng/ml ssDNA has been achieved. Possible interfering organic compounds, cations and anions have been tested. The method has been applied for the drug determination in urine samples, down to 0.23ng/ml could be easily achieved in such samples.