An ultrasound assisted modified solid phase micro-extraction technique for enrichment of cadmium and lead in aqueous extract of coal gangue soil samples
Ayaz Ali Lashari, Ayaz Ali Lashari, Tasneem Gul Kazi, Jameel Ahmed Baig, Hassan Imran Afridi, Anjum Lashari, Anjum Lashari, Fazeela Kandhro
Abstract
The present study was carried out to develop a green and novel ultrasonically modified solid phase micro-extraction method (Um-SPµE) to quantify the cadmium (Cd2+) and lead (Pb2+) in acidic water extract (pH < 6.5) of coal gangue soil (CGS) samples collected from the block II of Thar coal field Sindh Pakistan. The 8-hydroxyquinoline (8-HQ) embedded benzophenone allows quantitative enrichment of the Cd2+ and Pb2+ at pH ∼ 6.0. The ultrasonic energy applied to enhance the dissolution/extraction of hydrophobic complex of Cd2+ and Pb2+ in deep eutectic solvent (DES), which synthesized by mixing of zinc chloride and acetamide at 1:2 mol ratios. The extraction capability of DES was enhanced by addition of a nonionic surfactant (Triton X-114) to improve the phase transfer ratio, to notably enhance the recovery of hydrophobic complex of Cd2+ and lead Pb2+. There were various factors (pH, concentration of ligand, adsorbent quantity, volume of DES and nonionic surfactant, and sonication time), effecting the enrichment factor, preconcentration and % recoveries of both metals; were optimized. The certified reference materials and spiking recovery test were applied to real samples in order to check precision and validity of the developed methodology. The % recoveries of both selected metals were found to be > 98% by applying developed method (p < 0.05).