SPECTROPHOTOMETRIC METHOD FOR THE DETERMINATION OF IODATE USING METHYLENE BLUE AS A CHROMOGENIC REAGENT

A simple, rapid and sensitive spectrophotometric method has been developed for the determination of iodate (IO3-) in table salt and sea water. The proposed method is based on the reaction of iodate with potassium iodide in an acid medium to liberate iodine. The liberated iodine bleaches the blue color of methylene blue and is measured at 665.6 nm. This decrease in absorbance is directly proportional to the iodate concentration and obeys Beer's law in the range of 0.5-14 μgmL–1 of IO3-. The molar absorptivity, Sandell's sensitivity, detection limit and quantitation limit of the method were found to be 1.24 x 104 L mol-1cm–1, 1.41 x 10-2 μgcm-2, 0.048 μgmL–1 and 0.145 μgmL-1, respectively. The optimum reaction conditions and other analytical conditions were evaluated. The effect of interfering ions on the determination has been 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, Methylene blue, Spectrophotometry, Table salt, Sea water Bull. Chem. Soc. Ethiop. 2006, 20(1), 143-147

An easy spectrophotometric determination of selenium using azure B as a chromogenic reagent

455-458A simple, rapid and sensitive spectrophotometric method has been developed for the determination of trace amounts of selenium in water samples, soil, plant materials and human hair. The proposed method is based on the reaction of selenium with potassium iodide in acidic medium to liberate iodine. The liberated iodine bleaches the violet colour of azure B, which is measured at 644 nm. This decrease in absorbance is directly proportional to selenium concentration. Beer’s Law was obeyed in the range 2.0-10.0 µgmL-1 of selenium. The molar absorptivity, Sandell’s sensitivity, quantitation limit and detection limit of the method were found to be 0.9473 10 5 L mol -1 cm -1, 8.33 10-4 µg cm–2, 0.070 µgmL-1 and 0.023 µgmL-1, respectively. The proposed method has been successfully applied to the determination of selenium in various samples

A highly sensitive spectrophotometric method for the determination of trace copper using azure B as a chromogenic reagent

28-31A simple, rapid and sensitive spectrophotometric method has been developed for the determination of trace amounts of copper in tap water, polluted water, human hair and alloys. The proposed method is based on the reaction of copper with potassium iodide in acidic medium to liberate iodine, which bleaches violet color of azure B and the absorbance is measured at 644nm. This decrease in absorbance is directly proportional to copper concentration. Beer’s Law was obeyed in the range 2.0-12.0μg/ml of copper. Molar absorptivity and Sandell’s sensitivity of the method were found to be 1.760 x 10⁵ l /mol/cm and 3.61 x 10-4μg/cm² respectively. The developed method has been successfully applied to the determination of copper in tap water, polluted water, human hair and alloys

Spectrophotometric determination of dissolved oxygen in water

593-595A simple, rapid and sensitive spectrophotometric method has been developed for the determination of dissolved oxygen (DO) in river water samples. The method is based on the reaction of dissolved oxygen with manganous sulphate in alkaline iodide-azide solution and the liberation of iodine by manganese dioxide. The liberated iodine bleaches the violet colour of azure B which is measured at 644 nm. The decrease in absorbance is directly proportional to dissolved oxygen concentration and obeys Beer’s law in the range 0.2-1.4 gmL-1. The molar absorptivity, Sandell’s sensitivity, detection limit and quantitation limit of the method were found to be 5.86 104 Lmol-1 cm-1, 3.66 10-3 g/cm2, 0.030 and 0.090 gmL-1, respectivel

<b>Spectrophotometric method for the determination of iodate using methylene blue as a chromogenic reagent</b>

A simple, rapid and sensitive spectrophotometric method has been developed for the determination of iodate (IO₃^-) in table salt and sea water. The proposed method is based on the reaction of iodate with potassium iodide in an acid medium to liberate iodine. The liberated iodine bleaches the blue color of methylene blue and is measured at 665.6 nm. This decrease in absorbance is directly proportional to the iodate concentration and obeys Beer's law in the range of 0.5-14 μgmL^-1 of IO₃^-. The molar absorptivity, Sandell's sensitivity, detection limit and quantitation limit of the method were found to be 1.24 x 10⁴ L mol^-1cm^-1, 1.41 x 10^-2 μgcm^-2, 0.048 μgmL^-1 and 0.145 μgmL^-1, respectively. The optimum reaction conditions and other analytical conditions were evaluated. The effect of interfering ions on the determination has been described. The proposed method has been successfully applied to the determination of the iodate in the table salt and sea water

Spectrophotometric determination of arsenic in environmental and biological samples

36-40A simple and sensitive spectrophotometric method has been developed for the determination of arsenic using variamine blue as a chromogenic reagent. The method is based on the reaction of arsenic(III) with potassium iodate in acid medium to liberate iodine, which oxidizes variamine blue to form a violet coloured species having an absorption maximum at 556 nm. Beer’s law is obeyed in the range 0.2-14 μg mL-1 of As(III). The molar absorptivity, Sandell’s sensitivity, detection limit and quantitation limit were found to be 1.43104 L mol-1cm-1, 5.2610-2 μg cm-2, 0.022 and 0.072 μg mL-1, respectively. The optimum reaction conditions and other analytical parameters were evaluated. The proposed method has been successfully applied for the determination of arsenic in various environmental and biological samples

A facile spectrophotometric method for the determination of hypochlorite using azure B

573-575A simple, rapid and sensitive spectrophotometric method has been developed for the determination of hypochlorite using azure B. The method is based on the reaction of hypochlorite with potassium iodide in acidic medium to liberate iodine. The liberated iodine bleaches the blue color of azure B which is measured at 644 nm. The decrease in absorbance is directly proportional to the concentration of hypochlorite in the range 0.2-1.0 μgml-1. The molar absorptivity, Sandell sensitivity, detection limit and quantitation limit are found to be 1.49×104 lmol-1cm-1, 3.25×10-4 μgcm-2 , 0.1131μgml-1 and 0.3429 μgml-1. respectively. The method has been successfully applied to the determination of hypochlorite in some real samples on