PAKISTAN SOCIETY OF PHARMACOGNOSY & NATURAL THERAPY
PAKISTAN SOCIETY OF PHYTOPHARMACOLOGY & THERAPEUTICS
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EFFECT OF IMMISCIBLE PHASE ON THE FORMAL POTENTIAL
OF A REDOX REACTION

S. Azhar Ali* and Saima Khan
Department o(Chemistry. University of Karachi, Karachi-75270, Pakistan



ABSTRACT: The potentia1 difference at platinum test electrode, in ferrous ammonium sulphate/potassium dichromate system, in the presence of immiscible phase (chloroform, ethyl acetate, hexane, and xylene) vs. saturated calomel electrode, was determined using potentiometry. Effect of various parameters, such as, concentration of redox system and volume of immiscible phase were determined at 30:tl "c. The presence of immiscible phase produced a linear response to the formal potential of Fe'+ /Fe2+ system. However, chloroform showed a non-linear response, while xylene produced insignificant effect on the formal potential. Such abnormal behavior was correlated to the dielectric constant values of immiscible phase, comparative to the redox system. The results were proposed to be applicable for the identification/isolation of biologically active compounds pertaining to their applications in pharmaceutical industry.

Key Words: Phase effect, Formal potential, Redox system, Potentiometry.