Abstract
The azo organic reagent (1,5-dimethyl-2-phenyl-4-((2,3,4-trihydroxy phenyl) diazenyl)-1H-pyrazol-3(2H)-one) (DPTPD) was prepared and used for the spectrophotometric determination of cobalt(Ⅱ) and Lead(Ⅱ), by the selective and surfactant-sensitized method based on the ternary complexes formation of Co(Ⅱ) and Pb(Ⅱ). The reagent had absorption maximum at 381 nm, and reacted with Co2+ to form a purple reddish complex with λmax = 430 nm at pH = 7.5, while it formed a red complex with Pb2+ of λmax = 417 nm at pH= 6. Beer's law for the determination over the range of 1 - 25 ppm and 1 - 33 ppm for Co(Ⅱ) and Pb(Ⅱ), respectively. The molar absorptivity (Є) and Sandell's sensitivity values of Co(Ⅱ) and Pb(Ⅱ) complexes were found to be 1.02 × 104, 3.3 ×104 mol-1 cm-1, and 0.0725, 0.0269 μg cm-2 at 430, 417 nm, respectively. The stability constant was found to be 1.1 × 108 L mol-1 and 2.3 × 108 L mol-1 for Co(Ⅱ) and Pb(Ⅱ), respectively. Detection limit relative standard deviation, relative error and recovery were predestined for 15 ppm standard solution of Co(Ⅱ) and Pb(Ⅱ) complexes, respectively. The important interferences with most ions like Cr+3, Mn2+, Fe3+, Zn2+, Hg2+, Mo+2, Pt2+ and Cd+2 were studied using the appropriate masking agents. The method was applied for the determination of Co(Ⅱ) in filling sample; the result obtained was incompatible with that by the flame atomic absorption spectrometry method. The organic reagent (DPTPD) was diagnosed as an anti-bacterial and an antioxidant.
