Study on color reaction of a new reagent 2-(1,3,4-triazolylazo)-5-diethylaminobenzoic acid with nickel

In this paper,the conditions of color reaction of a reagent 2-(1,3,4-triazolylazo)-5-diethylamino-benzoic acid(TZDBA) with Ni2+ are reported.It is found that this new color reagent reacts with Ni2+ to form a stable purple red complex in the medium of HAc-NaAc at pH 5.0.The maximum absorption wavelength and apparent molar absorptivity are 560 nm and e=3.82×104 L·moL-1·cm-1 respectively.Beer′s law is obeyed in the range of 0～0.8 mg/L for nickel.The complex will not be decomposed by adding some mineral acids,while complexes formed by other coexisting ions will be decomposed with TZDBA,thus the selectivity is improved.The method has been applied to the direct determination of trace nickel in pure magnesium and alumunium alloy with satisfactory results.