STUDY OF THE SYNTHESIS OF A NEW CHROMOGENIC REAGENT 2,5-DIMETHOXY-4-CHLOROBENZENEDIAZOAMINOAZOBENZENE AND ITS COLOR REACTION WITH CADMIUM(Ⅱ)

A new chromogenic reagent,2,5-dimethoxy-4-chlorobenzenediazoaminoazobenzene (DMOCDAA) was synthesized,and its molecular composition and structure were analyzed and verified by elementary analysis and IR-spectrometry.In a borate buffer of pH 11.5,and in the presence of Triton X-100,a stable complex with mole ratio (R∶Cd) of 2 to 1 was formed by the reaction of DMCDAA with Cd(Ⅱ),having its absorption maximum at 526 nm,and apparent molar absorptivity ε526of 2.1×105L·mol-1·cm-1.Beer′s law was kept in the range of 0-20 μg of Cd(Ⅱ) per 25 mL of solution.The linear regression equation was given as follows: A=0.012 1+0.074 3 C (r=0.999 6),where C denotes μg of Cd(Ⅱ) per 25 mL solution.This method has been used for the determination of cadmium in aluminum alloys,giving RSDs less than 2.5%,and recoveries in the range of 104%-106%.