Flow-injection spectrophotometric determination of periodate and iodate by their reaction with pyrogallol red in acidic media

A simple and efficient flow-injection method was used with good results to determine periodate and iodate in water. The method is based on the reaction of periodate or iodate with pyrogallol red in sulfuric acid media. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of pyrogallol red at 470 nm. The chemical and FIA variables were established using the univariate and simplex optimization methods. The calibration curve was linear over the concentration ranges of 0.8-73.0 and 2.0-100.0 microM for IO4- and IO3-, respectively. The detection limits were 0.7 and 1.0 microM for IO4- and IO3-, respectively. The sample throughput was 20 +/- 5 h(-1). The influence of potential interfering ions in the determination of the anions was tested. The relative standard deviations for 4.20 and 5.73 microM periodate and iodate were 1.8 and 2.2%, respectively.