Determination of Mercury in Food and Water Samples by Displacement-Dispersive Liquid-Liquid Microextraction Coupled with
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Determination of Mercury in Food and Water Samples by Displacement-Dispersive Liquid-Liquid Microextraction Coupled with Graphite Furnace Atomic Absorption Spectrometry Pei Liang & Juan Yu & Enjian Yang & Yajun Mo
Received: 5 February 2014 / Accepted: 12 May 2014 # Springer Science+Business Media New York 2014
Abstract A novel method was developed for the determination of mercury by displacement-dispersive liquid-liquid microextraction (D-DLLME) combined with graphite furnace atomic absorption spectrometry. The D-DLLME method is based on two steps of dispersive liquid-liquid microextraction (DLLME). First, Cu2+ reacted with pyrrolidinedithiocarbamate (PDC) to form Cu-PDC complex and extract with DLLME procedure; then, the sediment phase was dispersed into the sample solution containing Hg2+ with dispersive solvent, and another DLLME procedure was carried out. Since the stability of Hg-PDC is higher than that of Cu-PDC, Hg2+ can displace Cu2+ from the preextracted Cu-PDC complex and enter into the sediment phase. As a result, Hg2+ was preconcentrated, and the interference from coexisting metal ions with lower PDC complex stability was largely eliminated as they cannot displace Cu2+ from Cu-PDC complex. Under the optimal conditions, the limit of detection was 19 ng L−1 (3σ) for mercury, and an enhancement factor of 62 was achieved with a sample volume of 5.0 mL. The accuracy of the developed method was evaluated by analysis of the certified reference material GBW08508 rice flour. The method was successfully applied to determine the trace mercury in food and water samples with satisfactory results. Keywords Displacement-dispersive liquid-liquid microextraction . Mercury . Graphite furnace atomic absorption spectrometry . Food and water samples
P. Liang (*) : J. Yu : E. Yang : Y. Mo Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, People’s Republic of China e-mail: [email protected]
Introduction Mercury (Hg) is an environmentally and toxicologically important element and is considered by the US Environmental Protection Agency as a highly dangerous element because of its high toxicity and very high bioaccumulation factor (up to 106) in the food chain (Tchounwou et al. 2003; Leopold et al. 2010). Although Hg is not an abundant chemical element in nature, it is released to the environment through natural and anthropogenic processes and distributed globally (Cheng and Hu 2012). Hg is a human health hazard because it may cause kidney toxicity, neurological damage, paralysis, chromosome breakage, and birth defects, and can also be destructive to natural metabolism, incretion, and procreation of organism, leading to maladjustment in hormone secretion (Baughman 2006; Holmes et al. 2009). Food and drinking water are the largest sources of exposure to Hg for the general population. The Joint Food and Agriculture Organization/World Health Organization (FAO/WHO) Expert Committee on Food Additives and Contaminants (JECFA) has se
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