Adsorptive Wave of Triple Complex of Lead with Furoylpyrazolone and 2,2′-Dipyridine

In a medium of HAc-NaAc( pH = 3. 51) , a triple complex is formed via Pb(Ⅱ) reacting with 1-phenyl-3-methyl-4-(α-furoyl) pyrazolone-5 (HPMαFP) and 2, 2'-dipyridine (dipy) , and there appears a sensitive polarographic wave at -0. 73 V(vs. SCE) for the triple complex. The peak current exhibits linear relation with the concentration of Pb(Ⅱ) from 2×10～9 g/mL to 9×10～6 g/mL. The detection limit is 2×10-9 g/mL. By using different electrochemical methods, the properties of the polarographic wave and the mechanism of electrode reaction were studied. The results indicate that the polarographic wave at - 0. 73 V is an adsorptive wave of the complex. The peak current is produced by the reduction of the Pb (Ⅱ) ion . The molar ratio of Pb(Ⅱ) with dipy to HPMaFP in the complex is 1:1:1; and the conditional formation constant of the complex is 5. 06×106. The method was used to determine lead in thick salt, cane sugar and comestic samples. The recovery is 99. 3%～100. 4% .