FI-Photometric Determination of Iodate in Table Salt

Based on the color reaction of iodate with p-phenylenediamine in dil. HCl medium,a FI-photometric method for determination of iodate in table salt was proposed. Conditions of color reaction in the FI-system,i.e.,the concentrations of HCl solution and the p-phenylene diamine solution,were studied and optimized. Linearity range of the method was found to be 0.05-10.0 mg·L-1,at room temperature,when the concentration of HCl solution and the p-phenylene diamine solution were 0.5 mol·L-1 and 10 g·L-1,respectively. Detection limit (3S/N) found was 0.006 3 mg·L-1. Precision of the method was tested at IO-3 concentration of 1.0 mg·L-1 for 11 determinations,giving value of RSD of 1.07%. Based on 2 samples of table salt with known contents of iodate,recovery was tested by standard addition method,values of recovery found were ranged from 99.8% to 101.6%.