A simple and rapid cloud point extraction methodology has been developed for the separation and preconcentration of palladium (Pd2+), gold (Au3+), and silver (Ag+) ions. The metal ions in the initial aqueous solution were complexed with 4-allylthiosemicarbazide, and Triton X-114 was added as surfactant. Dilution of the surfactant-rich phase with acidified metanol was performed after phase separation, and the metal ions were determined by graphite furnace atomic absorption spectrometry. The main factors affecting the cloud point extraction procedure, such as pH, concentration of the ligand, amount of Triton X-114, equilibrium temperature, and incubation time, were investigated and optimized. Under the optimum experimental, the calibration graphs were linear upto 100 μg L−1 for Pd2+ and Au3+ and up to 80 μg L−1 for Ag+. The enrichment factors were 48, 53, and 51 for Pd2+, Au3+, and Ag+, respectively. The limits of detection, based on three times the standard deviation of the blank signal by seven replicate measurements, were 0.15, 0.07, and 0.04 μg L−1 for Pd2+, Au3+, and Ag+, respectively. The accuracy of the results was verified by analyzing spiked real samples (water, blood, and urine) as well as by comparison the results of geological samples with those obtained by ICP−MS after solvent extraction using ammonium pyrrolidinedithiocarbamate in methyl isobutyl ketone. The proposed method has been applied for the determination of the metal ions in real samples with satisfactory results.
Optimization of coal trace metal analysis by graphite furnace atomic absorption spectrometry
