Spectrophotometric Determination of Lead(II) with 3-Hydroxy-3-m-Tolyl-1-o-Chlorophenyltriazene

Abstract

3-Hydroxy-3-m-tolyl-1-o-chlorophenyltriazene has been used

for the spectrophotometric determination of Pb(II). The reagent

forms yellow lead complex composition 1 : 2 (Pb : R) between pH

6.9–7.3. Absorbance measurements were made at 404 nm. Values

of molar absorptivity, Sandell's sensitivity, stability constant

(log K) and free energy of formation were found to be 14,500 L

mol^–1 cm^–1, 14.3 ng/cm², 9.65 and 13.247 kcal/mol respectively.

Beer's law is obeyed in the entire concentration range studied,

i.e., 1.0 x 10^–5 M to 6.0 x 10^–5 M. It was possible to determine lead

(8.28 mg) in presence of twofold molar excess of twenty cations

and anions.