Optimization of kinetic determination of iodate by methyl orange oxidation in the presence of hydrazine

Instead of the fixed time method the difference in induction periods of decolorization of a blank solution and a sample solution has been suggested as analytical signal for iodate ion determination by Landolt reaction of methyl orange with potassium bromate in the presence of hydrazine. Optimal conditions are: 0.024 M H 2SO 4,2x10 -6M methyl orange, (5-6)x10 -5 M KBrO 3, 1x10 -5 N 2H 4. Calibration curve is linearin (0.06-2.4) µg/mL range, reproducibility error is less than 2.7%, relative error of determination is less than 3.3 %, for aqueous solution analysis.