Abstract
A simple and sensitive kinetic spectrophotometric method for the determination of nanomolar level of Acid Red 18, based on the catalytic effect of silver nanoparticles on the oxidation of Acid Red 18 by potassium periodate is described. The reaction rate was monitored spectrophotometrically by measuring the decrease in absorbance of Acid Red 18 at 505 nm. The detection limit of the method was 0.18 ng/mL and the linear range was between 0.5–485 ng/mL. The effects of acidity, concentration of reactants, reaction time, and external ions were also discussed. The optimum reaction conditions were fixed and some kinetic parameters determined. The relative standard deviation for the determination of Acid Red 18 at the concentration of 100 ng/mL was calculated to be 0.998 % (n = 10). The method has been successfully applied to the determination of Acid Red 18 in city, tap, and river water samples.