A study on the determination of iodine in water by flow injection analysis without arsenic

Abstract

Objective To establish a method for automatic determination of iodine content in drinking water by flow injection analysis (FIA) without arsenic. Methods In the dilute nitric acid solution, iodide ion in appropriate amount of nitrous acid solution could catalyze the orange red iron thiocyanate complex fade, and the use of this method combined with flow injection analysis technology formulated a flow injection method, and experimental conditions of the method were optimized. The linear relationship and linear range of the standard curve, the detection limit, the precision and the accuracy of the sample determination were implemented under the optimized conditions. Results The optimum concentration of potassium thiocyanate solution (0.15 mol/L) and sodium nitrite was 27.30 ml and 8.00 g/L, respectively, by series of experimental studies. Under the condition, the linear range of the standard curve was 0-500 μg/L, the standard curve linear relationship coefficient ≥0.999 0; method detection limit was 5.94 μg/L; in precision experiment of low, medium and high concentrations of iodine, the coefficients of variation were 1.19%, 1.92% and 2.06%; in accuracy test, recovery rates were 100.49%-107.84%, and the total recovery rate was 103.15%. Conclusions The flow injection analysis method can be used to replace arsenic cerium catalyzed spectrophotometric detection of iodide in water; when the method is used in detection of the sample water iodide content of 0-500 μg/L, it has good precision and accuracy, automatic injection, automatic filling reagents and automatic detection system to reduce the burden on the staff, with arsenic-free reagents and reduced environmental pollution and the health hazards of the inspectors, which is suitable for iodine screening in high iodine areas. Key words: Drinking water; Iodine; Arsenic; Flow injection analysis