Abstract

Usha Maroo, Pradeep Maroo, R. S. Chauhan and D. N. Purohit

3-Hydroxy-3-m-tolyl-1-p-chlorophrnyltriazene with Pb(ll) forms a 1:2 [Pb(ll):R] acetone soluble yellow complex with maximum absorbance at 400 nm. The working wavelength was chosen as 430 nm (ε =11,900). For spectrophotometric determination the optimum Pb:R ratio was 1:6 and pH range for maximum constant absorbance was 6.8-7.2. Values of molar absorptivity, Sandell's sensitivity, stability constant (log β) and free energy of formation were 11,900 1. mole-1cm-1, 17.4 ng/cm2, 9.53 and -13.082 K/Cal/mole respectively. Beer's law is obeyed in the entire concentration range studied i.e, 1.0 x10-5 M to 6.0 X 10-5 M. It was possible-to determine lead (6.26 ppm) in presence of two fold molar excess of twenty cations and anions.

chlorophrnyltriazene; absorptivity; anions

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