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Spectrophotometric determination of trace concentrations of lead using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in the presence of nonionic surfactants

M. Nováková and V. Kubáň

Department of Analytical Chemistry, J. E. Purkyně University, CS-611 37 Brno


Abstract: On the basis of thorough spectrophotometric study of the chelate-forming reactions of the Pb(II) ions with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (BrPADAP) in aqueous—ethanolic medium containing nonionic surfactants, the optimum conditions for elaboration of a highly sensitive and selective method of determination of trace concentrations of lead have been found. In the medium containing 50 vol. % ethanol, TRITON X-100 (ϱ=3 g dm-3), and 0.1 mol dm-3 ammonia or hexamethylenetetramine buf­ fer of pH = 8, the PbL+ chelate exhibits the value of molar absorption coefficient  ϵ=6.5 mmol-1 m2 at λ=575 nm, the logarithm of the condition­al stability constant being log {ß} = 10.6. By using KCN (c=2x10-2 mol dm-3), thiourea (c=1x10-2 mol dm-3), and KF (c=5x10-4mol dm-3) the interfering influence of the majority of multivalent elements can be eliminated and the method enables us to determine g(Ph) present in tens of ng cm-3 (c = 2 x 10-8—2x10-5 mol dm-3 ) within accuracy exceeding 1 % rel.

Full paper in Portable Document Format: 422a183.pdf


Chemical Papers 42 (2) 183–195 (1988)

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