Separation, Preconcentration, and Determination of Lead, Cadmium and Iron Using Cloud Point Extraction with FAAS

The concentration of heavy metals in drinking water is a significant standard for water quality evaluation and water pipeline corrosion detection. This research aimed to develop a new method based on cloud point extraction (CPE) for the separation, preconcentration and detection of lead, cadmium, and iron with flame atomic absorption spectrometry (FAAS) when the concentration of metallic trace elements in the sample was lower than the limits of detection (LOD). The experimental LODs for Pb, Cd and Fe, determined based on significant sensitivity change and break in the slope of the standard curve, were 0.01, 0.01, and 0.3 ppm, respectively. With joint utilization of both 2,6-diamino-4-phenyl-1,3,5-triazine (DPT) and 3-amino-7-dimethylamino-2-methylphenazine (Neutral Red, NR) as chelating agents, and using Triton X-114 as surfactant, those metallic elements could be effectively enriched in water samples. The preconcentration procedure was optimized by varying the experimental factors such as temperature, equilibrium time, pH, and the concentration of the chelates and surfactant. With the optimization, this method allowed the determination of these three trace elements with a 20-times reduced LOD and yielded substantial recoveries of 99.8, 97.3 and 99.3% for Pb, Cd and Fe, respectively.