Solvent Extraction and ICP-MS Determination of Lead Using a Fullerene-Based Hydroxamic Acid: Spectrophotometric Characterization and Applications to Environmental and Forensic Samples

A selective extraction and preconcentration method is reported for the determination of Pb(II) using N-phenyl(1,2-methano-fullerene C60)-61-formohydroxamic acid (PMFFA). Pb(II) forms a yellow complex with PMFFA at pH 9.0, and the complex is extracted into dichloromethane for spectrophotometric measurement and subsequent ICP-MS determination under optimized instrumental conditions. The PMFFA extract showed a molar absorptivity of 8.0 × 104 L mol-1 cm-1 at 460 nm and obeyed Beer’s law over 0.20 to 5.0 µg mL-1. The spectrophotometric method gave an LOD of 0.132 µg mL-1, an LOQ of 0.436 µg mL-1, and a recovery of 99.3%. ICP-MS determination after PMFFA-based preconcentration was linear over 2.5 to 62.0 ng mL-1, with an LOD of 0.01 ng mL-1 and an LOQ of 0.03 ng mL-1. The formation of a 1:2 Pb(II)-PMFFA complex was supported by slope-ratio analysis, with an extraction constant of 6.04 ± 0.02 × 1012 and an apparent stability constant log βKe of 18.50 ± 0.02 at 298 K. The method showed high recovery, low matrix interference, and reproducibility in reference materials and diverse environmental, biological, industrial, and forensic samples, demonstrating PMFFA’s potential for Pb(II) extraction, preconcentration, and determination.