SPECTROPHOTOMETRIC METHOD FOR THE DETERMINATION OF TRACE AMOUNT OF TUNGSTEN (VI) IN ALLOY SAMPLES USING 4-HYDROXYBENZALDEHYDETHIOSEMICARBAZON

Abstract

A simple ultra-sensitive non extractive spectrophotometric method for the determination of tungsten (VI) using the reagent 4- hydroxybenzaldehyde thiosemicarbazone (4-HBTS). The reagent 4-HBTS gives Yellow color with tungsten (VI) solution of weak acidic medium p H 6.0 and the maximum absorbance was observed at 365 nm, Beer’s law is obeyed in the range.0.7354 to 7.354 μg/ml. The linear plot can be fitted into the equation A356 = 0.0186C + 0.0149. The molar absorptivity and Sand ell’s sensitivity values are 1.4 x 104 L mol-1 cm-1 and 0.00128μg/cm2 respectively. The stability constant of 1:1 tungsten (VI) - 4-HBTS complex is calculated and is found to be 6.7 x 106. The influence of interferences on the proposed method was studied and presented. The procedure was successfully applied for the determination of tungsten in different alloy samples.