Application of Dispersive Liquid-Liquid Microextraction with Graphite Furnace Atomic Absorption Spectrometry for Determination of Trace Amounts of Zinc in Water Samples
A selective and simple method for separation and preconcentration of zinc ions was developed by using dispersive liquid-liquid microextraction. Parameters that have an effect on the microextraction efficiency such as volume of extraction and disperser solvent, extraction time, and adding salt were investigated. Under optimum conditions, a preconcentration factor of 250 was obtained. The limit of detection (LOD) obtained under the optimal conditions was 0.09？ng？mL？1. The linearity of method was obtained in range of 0.2–50？ng？mL？1 with a correlation coefficient ( ) of 0.9974. The relative standard deviation for 10 replicate determinations at 1.0？ng？mL？1 of zinc was 2.53%. The proposed method was successfully applied to the analysis of zinc in water sample. 1. Introduction Zinc is an essential trace element for humans, animals, plants, and microorganisms. The zinc content in humans is 2–4？g [1]. Zinc plays many fundamental roles in cell replications, gene expression, and in the metabolism of nucleic acid and different proteins [2]. The sensitive, selective, and rapid methods for the determination of zinc are in great demand. Atomic absorption spectrometry (AAS) [3], graphite furnace atomic absorption spectroscopy (GF-AAS) [4], neutron activation analysis (NAA) [5], inductively coupled plasma-atomic emission spectroscopy (ICP-AES) [6], inductively coupled plasma-mass spectrometry (ICP-MS) [7], direct current plasma atomic emission spectrometry (DC-PAES), and X-ray fluorescence are widely applied to the determination of zinc at trace level. Preconcentration technique allows the improvement of detection limit as well as the selectivity of the method. Sample preparation is one of the most important and crucial steps in the whole analytical process. It is often also the bottleneck for rapidly obtaining the desired results, especially for the determination of trace analytes in samples with complex matrix. For the preconcentration and sample preparation several different microextraction methods have been developed, including liquid-liquid extraction [8, 9], solid phase extraction (SPE) [10], sorption and chelating ion exchange [11], solid phase microextraction [12], homogeneous liquid-liquid extraction [13, 14], and dispersive liquid-liquid microextraction (DLLME) [15–17]. In this work, a dispersive liquid-liquid microextraction coupled with graphite furnace atomic absorption spectrometry (GFAAS) has been developed and optimized for the extraction and determination of zinc. The method is based on chemical complexation of zinc(II) by Phenanthraquinone monophenyl
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