Study on synthesis of 5,6-dichlorbenzothiazole diazoaminoazobenzene and its color reaction with nickel

A new chromogenic reagent 5,6-dichlorbenzothiazole diazoaminoazobenzene(DCBTDAA) is synthesized and its color reaction with nickel(Ⅱ) is studied.Results showed that a red complex of DCBDAA and nickel(Ⅱ) with a reagent: metal ratio of 2∶1 was formed in the buffers solution of Na2B4O7-NaOH at pH 10.56 in the presence of Triton X-100.The complex have the maximum absorption at 540 nm with an apparent molar absorptivity of 2.5×105 L·mol-1·cm-1.Beer's 1aw was obeyed in the range of 0-15 μg/25 mL for nickel(Ⅱ).The method has been applied to the determination of nickel in standard aluminium alloy samples and the results compare favourably with the certified values.