Cloud point extraction and spectrofluorimetric determination of aluminium and zinc in foodstuffs and water samples

Cloud point methodology was successfully used for the extraction of trace amounts of aluminium and zinc as a prior step to their determination by spectrofluorimetry. Aluminium and zinc react with 8-hydroxyquinoline in a surfactant solution yielding a hydrophobic complex, which then is entrapped in surfactant micelles. Optimization was performed of the variables affecting complexation and phase separation. Under the experimental conditions used, preconcentration of 25 ml of sample in the presence of 0.12% (v/v) Triton X-114 permitted the detection of 0.79 μg l−1 of aluminium and 1.2 μg l−1 of zinc, respectively. The relative standard deviation for five replicate determinations of aluminium and zinc at 40 and 100 μg l−1 concentration level, were 2.72 and 2.1%, respectively. Good recoveries in the range of 95–104% were obtained for spiked samples. The proposed method was applied to the determination of aluminium and zinc in different samples.