Color Reaction of 2-(5-Carboxy-1,3,4-triazolylazo)-5-diethylamino Benzoic Acid with Nickel

Optimum conditions of the colour reaction of 2-(5-carboxy-1,3,4-triazolylazo)-5-diethylamino benzoic acid(abbreviated as CTZDBA)with Ni2+ are reported.It were found that the colour reagent reacts with Ni(II)to form a stable purple red complex(2:1)in the buffer solution of HAc-NaAc with pH 5.0.The maximum absorption wavelength and apparent molar absorptivity were found to be 562 nm and 3.67×104 L·mol-1·cm-1,respectively.Beer's law was obeyed in the rang of(0~0.8)mg/L of Ni(II).The method has been applied to the direct determination of nickel in nickel catalyst with satisfactory result.The recovery of standard addition is 97.5%～104.8%,with precision of 1.26%(RSD,n=6).