Cloud point preconcentration and flame atomic absorption spectrometry: application to the determination of cadmium
Cloud point methodology has been successfully used for the preconcentration of trace amounts of cadmium as a prior step to its determination by flame atomic absorption spectrometry. A procedure based on the formation of a complex with 1-(2-pyridylazo)-2-naphthol (PAN) is used for the preconcentration of cadmium in a surfactant-rich phase of Triton X-114. The chemical variables affecting the preconcentration step and the viscosity of the solution affecting the detection process have been optimized. Under the optimum conditions, a precision of 3.0% was achieved. The preconcentration of only 15 ml of sample with 0.05% Triton X-114 permits the detection of <0.4 ppb of cadmium with a concentration factor of 120.