Removing the interference of sulphite in the spectrophotometric assay of thiosulphate via charge transfer reaction

Sulphite ions were interfered in the spectrophotometric determination method of thiosulphate using charge transfer reaction, the proposed method has been described as an accurate, simple and rapid, which was based on charge transfer complex reaction between thiosulphate and xylenol-orange as a reagent using imidazole buffer at pH 7.6. The resulted red color complex which exhibited the highest absorption value which was measured at the selected wavelength 580 nm. The linearity of the proposed method was obeyed Beer’s law in the concentration range 10-700 µg/25ml of thiosulphate at 580 nm, the molar absorptivity 1.15×10⁴ l/mol.cm, and Sandell index for sensitivity 0.00975 µg/cm², the method exhibited a good recoveries of thiosulphate from various water samples successfully.