Combination of solid-phase extraction and flame atomic absorption spectrometry for simultaneous preconcentration and determination of some heavy metals in real samples

Abstract

A sensitive and simple method for the simultaneous preconcentration and extraction of trace amounts of Cd²⁺, Co²⁺, Cu²⁺, Ni²⁺, and Pb²⁺ ions in some real samples without using organic solvent has been reported. The method is based on the adsorption of these metal ions on 4-(2-Pyridylazo) resorcinol (PAR) loaded on activated carbon (AC). The retained analytes on modified activated carbon were eluted using 3.0 mL of 3.0 mol L⁻¹ nitric acid. The influences of the various analytical parameters including pH, amount of sorbent, sample volume, and eluent type on the recovery efficiencies were investigated. The experimental data were fitted to different conventional isotherm models including Langmuir and Freundlich isotherm. Generally, Langmuir model was found to represent the experimental isotherm data better than Freundlich model. The paper discusses the thermodynamic parameters of the adsorption (the Gibbs free energy, entropy, and enthalpy). Our results demonstrate that the adsorption process was spontaneous and exothermic. The effects of interference ions on retentions of the analytes were also examined. The recoveries of analytes were generally quantitative with a relatively low RSD. The method has been successfully applied for these metal ions content in some real samples.

Keywords:

• Heavy metal
• 4-(2-Pyridylazo) resorcinol
• Isotherm
• Kinetic
• Activated carbon
• Solid-phase extraction
• Atomic absorption spectrometry

Acknowledgements

The authors express their appreciation to the Semnan University Research Council for the support of this work.