Cloud point extraction combined with flow injection vapor generation inductively coupled plasma mass spectrometry for preconcentration and determination of ultra trace Cd, Sb and Hg in water samples

摘要

A simple and efficient cloud point extraction (CPE) procedure has been described for the preconcentration and separation of trace levels of Cd, Sb and Hg simultaneously from water samples for their determination by flow injection vapor generation inductively coupled plasma mass spectrometry (FI-VG-ICP-MS). The method was based on the formation of hydrophobic complexes of Cd, Sb and Hg with ammonium pyrrolidine dithiocarbamate (APDC), followed by their extraction, into a small volume of surfactant-rich phase, using a non-ionic surfactant Triton X-114. The main parameters affecting the extraction process such as concentration of complexing agent and pH, and also the amount of Triton X-l 14 were optimized. The surfactant-rich phase was dissolved with the carrier solution and then injected into VG-ICP-MS for Cd, Sb and Hg determination. The parameters affecting the vapor generation efficiency were also studied meticulously. Isotope dilution (ID) method was used for quantification work. The limit of detection for Cd, Sb and Hg was 0.002, 0.0006 and 0.005 ng mL~(-1), respectively. The accuracy of the procedure was verified by analyzing certified reference materials such as NRCC SLRS-4 River Water and NRCC SLEW-2 Estuarine Water reference materials, and also by applying it to a bottled mineral water, reservoir water and tap water samples obtained locally.