RESUMO
The electrochemical behavior of adriblastina has been studied at in situ mercury film electrode (in situ MFE) and platinum electrode (PtE) in the presence of phosphoric acid as supporting electrolyte using Osteryoung square-wave stripping voltammetry (OSWSV) and cyclic voltammetry (CV). Optimal experimental and operational parameters have been selected for the drug accumulation and determination in aqueous medium. The interaction of the drug with single stranded DNA (ssDNA) has been studied and validated by using classical least square and partial least square with propagation of error. The formal potentials E degrees and E degrees ' and the equilibrium constants K(1) and K(2) have been calculated. It was found that K(2) for the oxidized form of adriblastina is 63 times than K(1) for the reduced form. Among several possible interfering metal ions, a complex formation reaction was observed between adriblastina and Cu(II) ions at in situ MFE. Cu(II) ions formed 1:2 metal:drug complex which is more stable than ssDNA-drug interaction and consequently it inhibits drug biochemical damage effects. The copper complex offers sub-nanograms determination of adriblastina in that 5.80 and 180pg/ml could be easily detected in aqueous and urine media, respectively, with R.S.D. less than 4%. F-test and t-test have been applied in urine media giving good results that indicated the high accuracy of the proposed method.
RESUMO
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 0.134 ng/ml (5.51 x 10(-10) M). Calibration plots have been constructed at different accumulation times. The standard deviation (n=10) at a concentration level of 6 x 10(-8) M 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 degrees and E degrees ' and the equilibrium constants K(1) and K(2) have been calculated for the free form of Tarabine PFS and the bonded form with ssDNA, respectively. It was found that K(2) value for the bonded oxidized form is 298 times than that of K(1) 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 3 ng/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 0.23 ng/ml could be easily achieved in such samples.
