Synthesis of N,N′-Bis (Phenylazosalicylidene) Hydrazine and Its Use in the Square Wave Polarographic Determination of Micro Amounts of Cadmium

A new reagent,N,N′-bis (phenylazosalicylidene)-hydrazine (abbreviated as PASHZ) was synthesized and its molecular structure was identified by IR spectroscopy and elementary analysis.A binary complex was formed between PASHZ and Cd(Ⅱ) in an ammoniacal buffer medium of pH 9.1.Square wave voltammetric behavior of the new system containing PASHZ and Cd(Ⅱ) in the buffer medium of pH 9.1 was studied and a sensitive square wave voltammetric peak was observed at -0.867 V (vs.SCE).Linear relationship between the peak current (Ip) and the concentration of cadmium was obtained in the range of 1.0×10-6-1.0×10-4mol·L-1,giving the linear regression equation of Ip=9.745×106c+2.270 (r=0.999 4) with a detection limit of 0.5×10-6mol·L-1.In the application of the proposed method to the determination of microamounts of Cd(Ⅱ) in samples of mineral water and pure water,the results obtained were in consistency with the known values,and average values of RSD′s and recovery found were 2.72% and 98.6% respectively.