On-line Preconcentration and Determination of Zinc Using Zincon and Flame Atomic Absorption Spectrometry
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On-line Preconcentration and Determination of Zinc Using Zincon and Flame Atomic Absorption Spectrometry Rafaella R. A. Peixoto & Greice T. Macarovscha & Solange Cadore
Received: 2 August 2011 / Accepted: 3 October 2011 / Published online: 15 October 2011 # Springer Science+Business Media, LLC 2011
Abstract In this work, a method for on-line preconcentration and determination of zinc was developed. A miniglass column (35×3 mm) containing 70 mg of Dowex 1X8 resin modified with 1% (w/w) of zincon was coupled into the FIFAAS system. During the extraction procedure, it was verified that the metal reacts with the complexing reagent in the pH range from 9.0 to 10.0. After optimization of parameters such as type and concentration of the eluent, buffer concentration, elution time, sample and buffer flow rate, mixing coil length, and effect of foreign ions, the FIFAAS system presented an enrichment factor of 10 and at least 200 reutilizations of the column were possible. The detection limit was 0.67 μg L−1, and a relative standard deviation of 5% was obtained. The accuracy of the method was evaluated by using certified reference material, showing good accuracy. The proposed method was successfully applied for the determination of zinc in beverages. Keywords Zinc . Zincon . Solid-phase extraction . FI-FAAS
Introduction Zinc is an essential element to several living organisms, including the human being, where it plays structural, enzymatic, and regulatory roles (Cozzolino 2007). In humans, zinc has an important role in bone metabolism (Pedrosa and Cozzolino 1993), in controlling gonadal growth and development and in sexual maturation, which makes zinc a limiting growth factor (Urbano et al. 2002). It R. R. A. Peixoto : G. T. Macarovscha : S. Cadore (*) Institute of Chemistry—University of Campinas, P.O. Box 6154, 13083-970, Campinas, São Paulo, Brazil e-mail: [email protected]
is known that the concentration of zinc in the body can cause hormonal and biochemical changes that may affect health, including the cardiovascular system (Ronsein et al. 2004). Due to its essentiality in human health, the development of sensitive analytical methods for the determination of zinc in samples of foods and beverages, the main source of this element in human diet, becomes important. Among the analytical techniques for the determination of metals, atomic absorption spectrometry has been outstanding over the last 50 years (Skoog 2006). Flame atomic absorption spectrometry (FAAS) is usually employed for the determination of metals at the milligrams per liter level, showing some advantages such as selectivity and reproducibility, considering the huge range of atomic absorption spectrometers available on the market. However, FAAS presents less detectivity, restricting its use, depending on the level of analyte to be determined. In these cases, the analyte can be subjected to a prior treatment that allows its concentration. The concentration step may be carried out using several methods, such as coprecipitation (Aydin and Soylak 2007; Soylak
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