Abstract
A new procedure was developed for dispersive liquid-liquid micro extraction of cadmium prior to its determination by flame atomic absorption spectrometry. The major difficulty in combination of dispersive liquid-liquid microextraction with flame atomic absorption spectrometry is high background absorption of the extraction and disperser solvents that covers the absorbance of analyte. The background absorption was removed by changing the solvent of sedimented phase from organic to aqueous. In the proposed approach, tetrachloroethylene (C2Cl4) and tetrahydroforan (THF) were used as extraction and dispersive solvents respectively. Dithizone was used as complexing agent. Several factors that may be affect on the extraction process, such as, extraction solvent, disperser solvent, the volume of extraction and disperser solvent, extraction time, temperature of solution, concentration of chelating agent and pH were optimized. The effects of common coexisting ions on the recovery of cadmium were studied. Results showed that cadmium recoveries are almost quantitative in the presence of interfering ions. Under the optimal conditions the enrichment and enhancement factors were 34.5 and 26 respectively, the extraction and relative recoveries were 69% and 99% respectively, the calibration graph was linear in the range of 5-150 µg L-1, the detection limit was 1.2 µg L-1 and the relative standard deviation (n = 8) was 2.1%. The proposed method was applied successfully for determination of trace amounts of cadmium in water samples
Highlights
In the recent years, pollution of the environment by heavy metals has received considerable attention
It seems that slight reduction of extraction in high concentration of dithizone is due to the extraction of dithizone itself, which can saturate the small volume of extraction solvent
The background absorption has been removed, the absorbance of analyte is omitted. It seems that in these two methods, at evaporating step, cadmium ions are reduced by dithizone and stuck to the walls of the test tube. (iii) In this way, 0.2 mL of 0.5 mol L−1 nitric acid was added into sedimented phase and heated at 90 oC for 3 min until the organic solvents were evaporated completely
Summary
Um novo procedimento foi desenvolvido para microextração líquido-líquido dispersiva de cádmio antes de sua determinação por espectrometria de absorção atômica com chama. A maior dificuldade na combinação da microextração líquido-líquido dispersiva com espectrometria de absorção atômica é a alta absorção de fundo dos solventes de extração e dispersores que encobrem a absorbância do analito. Tetracloroetileno (C2Cl4) e tetrahidrofurano (THF) foram usados como solventes extrator e dispersivo, respectivamente, e, como agente complexante foi usada a ditizona. A new procedure was developed for dispersive liquid-liquid micro extraction of cadmium prior to its determination by flame atomic absorption spectrometry. The major difficulty in combination of dispersive liquid-liquid microextraction with flame atomic absorption spectrometry is high background absorption of the extraction and disperser solvents that covers the absorbance of analyte.
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