Accurate measurement and reporting of pH data have been a long-standing problem due to the effects of tem- perature and pressure. An increase in the temperature of any solutions will cause a decrease in its viscosity and an increase in the mobility of its ions in solution. An increase in temperature may also lead to an increase in the number of ions in solution due to the dissociation of molecules (this is particularly true for weak acids and bases). As pH is a measure of the hydrogen ion concentration, a change in the temperature of a solution will be reflected by a subsequent change in pH [7, 169]. pH reaction is difficult to be described with appropriate mathematical models, as it normally comes with inherent nonlinear dynamics with system uncertainty [6, 11].