Spectrophotometric Determination of Lead (II) Chelation by CaNa₂EDTA Using PAR (4-(2-Pyridylazo) resorcinol)

*¹Agor Emmanuel Achi; ¹Okafor Azubuike Ikechukwu and ^1,2Emuru Edward Odey

¹Department of Medical Biochemistry, University of Cross River State, Calabar, Nigeria

²Department of Biochemistry, University of Calabar, Calabar, Nigeria

^*Corresponding author: agoremmanuel13@gmail.com; +2348160920197

Abstract

The spectrophotometric determination of Lead(II) chelation was carried out using PAR (4-(2-pyridylazo)resorcinol) as a chromogenic reagent. The UV–Visible absorption spectrum of the Pb²⁺–PAR complex showed a maximum absorbance at 520 nm, which was selected as the analytical wavelength. The effect of incubation time indicated that complex formation was time-dependent, reaching equilibrium at approximately 25–30 minutes. The chelating activity of CaNa₂EDTA was evaluated by monitoring the decrease in absorbance of the Pb²⁺–PAR complex, with increasing chelator concentration resulting in a corresponding increase in percentage chelation. The observed inverse relationship between absorbance and chelation confirms the effective binding of Pb²⁺ ions by CaNa₂EDTA. Overall, the method proved to be simple, sensitive, and reliable for the determination of Pb²⁺ and its chelation and is applicable to the assessment of a wide range of chelating agents, including synthetic and plant-derived compounds.

Keywords: Lead(II), Spectrophotometry, PAR (4-(2-pyridylazo)resorcinol), Chelation, CaNa₂EDTA, Metal–ligand complex

CITE AS: Agor Emmanuel Achi; Okafor Azubuike Ikechukwu and Emuru Edward Odey (2026). Spectrophotometric Determination of Lead (II) Chelation by CaNa₂EDTA Using PAR (4-(2-Pyridylazo) resorcinol). IAA Journal of Biological Sciences 14(2):18-23. https://doi.org/10.59298/IAAJB/2026/1421823