Spectrophotometric Determination of Tellurium (IV) with Chrome Azurol S: Application to Sea Water and Synthetic Alloys

The detailed investigation of a sensitive spectrophotometric method for the determination of trace amounts of tellurium (IV) is described. The method is based on the reaction of tellurium (IV) with chrome azurol S in the presence of cetylpyridinium chloride hydrate surfactant at a final pH of 3.1 to form a pink coloured chelate absorbing maximum at 525 nm. Beers law is obeyed over the range (5-50) g/25 ml, with a molar absorptivity of (2.5 104) l.mol-1.cm-1 and a coefficient of determination (r2) of 0.9997. Sandells sensitivity index is (5.10410-3) g.cm-2, a relative error of (0.8-0.2%) and a relative standard deviation of (0.2 to 1.8) %, depending on the concentration levels in the calibration curve. The method has been applied successfully to determine Te (IV) in sea water and some synthetic alloys.