A Facile Spectrophotometric Method for the Determination of Iodate in Table Salt using New Chromogenic Reagents
A simple spectrophotometric method has been developed for the determination of iodate in table salt samples using thionin or azure B. The method is based on the reaction of iodate with potassium iodide in an acid medium to liberate iodine. The liberated iodine bleaches the violet colour of thionin or azure B, which are measured at 600 and 644 nm, respectively. This decrease in absorbance is directly proportional to the initial iodate concentration and obeys Beer’s law in the range of 1–12 μg mL–1 of iodate with thionin and 0.2–16 μg mL–1 of iodate with azure B. The molar absorptivity and Sandell’s sensitivity of using thionin and azure B were found to be 2.7×104 L mol–11 cm–1, 7.9×10–2 μg cm–2 and2.0 6 × 104 L mol–1 cm–1, 0.85×10–2 μg cm–2, respectively. The proposed method has been successfully used for the determination of iodate in table salt samples.
KEYWORDS: Iodate determination, spectrophotometry, thionin, azure B.
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