A Highly Sensitive Spectrophotometric Method for the Determination of
Iodate Using Leuco Xylene Cyanol FF

Chand  Pasha and  B. Narayana*

Department of Post Graduate Studies and Research in ChemistryMangalore University, Mangalagangothri – 574 199,Karnataka, India .* E-mail: nbadiadka@yahoo.co.uk , Fax: 0091-824-2287367

A highly sensitive and selective spectophotometric method has been developed for the determination of iodate (IO­3-) in table salt and sea water. The  proposed method is based on the oxidation of leuco xylene cyanol FF (LXCFF) to its blue form of xylene cyanol FF by iodate in sulfuric acid medium, the absorbance of the dye is measured in an acetate buffer medium (pH 4.0) at 620 nm. Beer’s law is obeyed in the range 0.4-14 mg mL-1 of iodate.  The molar absorptivity, Sandell’s sensitivity, detection limit and quantitation limit of the method were found to be 1.71 x 104  Lmol-1 cm –1, 1.02 x 10-2 mg cm-2, 0.026 mg mL–1 and 0.0806 mg mL-1 respectively. The optimum reaction conditions and other analytical conditions were evaluated.  The effect of interfering ions on the determination is described. The proposed method has been successfully applied to the determination of the iodate in the table salt and sea water.

Key words: Iodate determination, spectrophotometry, leuco xylene cyanol FF.