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Combined Cloud-Point Extraction And Spectrophotometric Detection of Lead and Cadmium in Honey Samples Using a New Ligand

Zuhair A-A Khammas, Azhar A. Ghali and Kasim H. Kadhim

A new, simple and reliable cloud-point extraction (CPE) combined with spectrophotometric method has been developed for the separation, preconcentration and determination of lead and cadmium ions. The method involved reaction of metal ions with newly synthesized 7-(6-methoxy 2-benzothiazolyl azo)-8-hydroxyquinoline [7-(6MBTA8HQ)] as chelating agent to form hydrophobic complexes. The formed 7-(6MBTA8HQ)2 Pb and 7-(6MBTAHQ)2Cd complexes were extracted at specific pH by cloudpoint procedure using nonionic surfactant Triton X-114 as extraction medium. The complexes were subsequently entrapped in surfactant micelles. The surfactant-rich phases were diluted with suitable solvent and the lead and cadmium contents were measured spectrophotometerically at their respective wavelengths maxima. The effect of several experimental parameters which impact the CPE efficiency was optimized by one-factor-at-a-time. Under the optimized conditions, enrichment factors of 114 and 84 were achieved for Pb (II) and Cd (II) ions respectively. The linear range of 5.00-100 ng mL-1, 0.32-7.50 ng mL-1 along with limit of detection 3.9 ng mL-1, 0.19 ng mL-1, precision expressed as relative standard deviation for seven replication measurements (10 ng Pb mL-1 and 0.94 ng Cd mL-1) of (1.12%) and (1.79%) and the recovery range of (96.27 ± 3.53) and (97.57 ± 3.48) were obtained for Pb (II) and Cd (II) ions, respectively. The developed method was applied for the determination of Pb and Cd in honey samples.