Verified email at uokufa.edu.iq
Faculty of Science/Department of chemistry
University of Kufa
Act in University of Kufa/Faculty of Science/Department of chemistry
Ph.D in physical chemistry
- Kinetics and thermodynamic of chemical reactions.
- Electro Chemistry and polarographic analysis.
- Theoritical Methods.
- Biophysical Chemistry.
- Spectroscopy techniques.
The potassium phosphate buffer as a supporting electrolyte of anticancer drug (5-fluorouracil (5 FU)) was the best among solutions of sodium phosphate buffer and Britton Robinson buffer in differential pulse polarography (DPP) at pH = 7.0 and T = 37 °C. The changes of temperature did not effect on inactivity of the supporting electrolyte (potassium phosphate buffer at T = 10-50 °C), and pH of the solution did not exceed 2% of each 5 °C (at pH = 7.0, by modified thermostat cell). However, the frequency measurements showed clear effect of temperature on diffusion current (IP /μA) of the chemotherapy compound in the range of 20-50 °C and under primary conditions. Then, the polarography measurements of 5-FU drug (at 10 μM, pH = 7 and T = 37 °C) gradually led to the optimum conditions: deposition potential =–0.9 V; drop size = 9.0 mm3; deposition time = 15.0 s; equilibration time = 5.0 s; pulse amplitude = 100 mV; pulse time = 7.0 ms; voltage step = 6 mV; voltage step time = 0.3 s; and sweep rate = 20.0 mV/s. The thermal assessment of 5-FU drug (after achievement of the optimum conditions) in a new thermostat vessel at HMDE by DPP showed that the reaction of 5-FU molecules represented pseudo first order reaction, instead of first order); the secondary waves of 5-FU drug may be due to formation of molecular complexes in aqueous solution and the reduction of 5-FU molecules at mercury surface electrode appeared as physisorption, instead of chemisorption.
Spectroscopic measurements of pharmaceutical compound 5-fluorouracil (5-FU) drug was achieved in solvents with different polarity. The drug gave clear absorption peak at 259, 269, 270 and 266 nm in hexane, dimethyl sulfoxide (DMSO), N, N-dimethylformamide (DMF) and ethanol, as well as phosphate buffer respectively, which was consistent with the standard values in literatures. The results of extension coefficient (ε) and wave length (λmax) showed reduction in polar medium as compared to non-polar medium. The calibration curve of 5-FU drug was achieved by using serials solutions dissolved in phosphate buffer (pH = 7.4 and T = 37 °C) within the range of 1×10–6 ~ 1×10–4 M. The stability of 5-FU drug was studied in phosphate buffer at pH = 5, 6, 7, 7.4 and 8 with 1×10–5 M and T = 37 °C, according to the equation of first-order reaction. The hydrolysis of 5-FU disappeared at alkaline solution, but had noticeable hydrolysis in acidic solutions with the rate constant 25, 14 and 20 at pH of 5, 6 and 7 respectively. The calculation of molar extension coefficient and half-life (t1/2) showed same sequence of 5-FU hydrolysis. Then, rearrangement of obtained results offered complicated reversible equilibrium state by the combination between thermodynamic and kinetic behaviors of 5-FU hydrolysis; with Keq = 8.46, 6.11 and 142.8 at pH of 5, 6 and 7 respectively. The acidic hydrolysis of 5-FU occurred spontaneously within free energy (ΔG) did not exceed 10 kJ/mol, which meant the electro motive forces of interactions were weak, notable to release energy such as Van der Waals forces or hydrogen bonding.