ABSTRACT
A facile and reliable UV-Vis spectrophotometric method associated with vortex-assisted dispersive liquid-liquid microextraction has been developed and applied to the determination of U(VI) at low levels in water samples. It was based on preconcentration of 24.0 mL sample at pH 8.0 in the presence of 7.4 µmol L(-1) 1-(2-pyridylazo)-2-naphthol, 1.0 mL of methanol as disperser solvent and 1.0 mL of chloroform as extraction solvent. A high preconcentration factor was achieved (396 times), thus providing a wide analytical curve from 6.9 up to 75.9 µg L(-1) (r=0.9982) and limits of detection and quantification of 0.40 and 1.30 µg L(-1), respectively. When necessary, EDTA or KCN can be used to remove interferences of foreign ions. The method was applied to the analysis of real water samples, such as tap, mineral and lake waters with good recovery values.
Subject(s)
Uranium/analysis , Water Pollutants, Radioactive/analysis , Chloroform/chemistry , Drinking Water/analysis , Hydrogen-Ion Concentration , Lakes/chemistry , Liquid Phase Microextraction/methods , Methanol/chemistry , Mineral Waters/analysis , Naphthols/chemistry , Solvents/chemistry , SpectrophotometryABSTRACT
Os sucos de frutas são considerados como uma boa opção de fonte de minerais e vitaminas. O consumo de sucos de frutas industrializados cresceu muito no Brasil, principalmente aqueles envasados em embalagens cartonadas da Tetra Pak®. Para avaliar o teor de minerais em sucos industrializados, foram analisadas as quantidades de sete metais (Zn, Ni, Pb, Fe, Cu, Cr e Na) em sucos de uva e pêssego (integral e light). Os minerais foram extraídos por meio da digestão com ácido clorídrico, e detectados por espectrofotometria de absorção atômica com atomização em chama. Não foram detectadas em quantidades significativas a presença dos metais Zn, Ni, Pb e Cu nos sucos. No entanto, Na, Cr e Fe foram detectados, sendo que o Cr apresentou uma concentração maior que a permitida pelas especificações da ANVISA (Agência Nacional de Vigilância Sanitária), indicando uma possível contaminação destes produtos. Vale ressaltar que o suco light de pêssego foi o que apresentou os maiores teores de ferro.
The fruit juices are considered a good option as a source of minerals and vitamins. The consumption of fruit juices has grown industrialized in Brazil, especially those packaged in cartons from Tetra Pak ®. To evaluate the content of minerals in industrialized juices were analyzed amounts of seven metals (Zn, Ni, Pb, Fe, Cu, Cr and Na) in grape juice and peach juice (integral and light). The minerals were extracted by digestion with hydrochloric acid, and detected by atomic absorption spectrometry with flame atomization. It was not detected in significant amounts to the presence of the metals Zn, Ni, Pb and Cu in the juices. However Na, Cr and Fe were detected, and Cr showed a higher concentration than allowed by the specifications of ANVISA (Agência Nacional de Vigilância Sanitária), indicating a possible contamination of these products. It is interesting to say that light peach juice showed the highest levels of iron.
