A simple, rapid and sensitive spectrophotometric method was developed for the determination of Se (IV) using Vanillin-2-aminonicotinic acid (VANA) as an analytical reagent. The reagent has been synthesized and characterized using IR, 1H NMR and mass spectral data. The metal ion in aqueous medium forms light greenish yellow colored complex with VANA at (pH= 5.0) (sodium acetate- acetic acid buffer solution) showing maximum absorbance at 360 nm. Hence, analytical studies were further carried out at 360 nm. The reagent reacts with selenium in acidic medium to form light greenish yellow colored 1:1 (M:L) complex . The color reactions are instantaneous and absorbance values remain constant for 24 hours. The composition of the Se (IV) complex with VANA was studied by the method of job’s continuous variation and molar ratio method. Beer’s law was obeyed in the range 0.06-3.48 μg ml−1of Se (IV). The molar absorptivity and Sandell’s sensitivity of the method were found to be 7.48 x 103 Lmol- 1cm-1 and 0.0013μg/cm-2 respectively. Since VANA method is more sensitive, it was applied for the determination of selenium in environmental samples.
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