Magnetic solid-phase extraction based on sulfur-functionalized magnetic metal-organic frameworks for the determination of methylmercury and inorganic mercury in water and fish samples.

A novel magnetic metal-organic frameworks (Fe3O4@UiO-66-SH) was successfully prepared by coating Fe3O4 nanospheres with sulfur-functionalized UiO-66. The Fe3O4@UiO-66-SH possesses both the magnetic properties of Fe3O4 and the diverse properties of metal-organic framework (MOF) in one material, which has the superiority of high surface area, easy-operation and strong adsorb ability with mercury, is used for the magnetic solid-phase extraction of methylmercury (MeHg+) and inorganic mercury (Hg2+) in water and fish samples. The analyzes were conducted by high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The different pretreatment conditions influencing the extraction recoveries of Hg2+ and MeHg+, including adsorbent amount, pH, extraction time, elution solvent, elution volume, desorption time, co-existing ions and dissolved organic materials were investigated. Under the optimized conditions, the limits of detection (LODs) of Hg2+ and MeHg+ for water samples were 1.4 and 2.6 ng L-1, and the limits of quantification (LOQs) of Hg2+ and MeHg+ for water samples were 4.7 and 8.7 ng L-1. The enrichment factors (EFs) were 45.7 and 47.6 fold for Hg2+ and MeHg+, respectively. The accuracy of the proposed method was demonstrated by analyzing the certified reference material of fish tissue (GBW10029) and by determining the analyte content in spiked water and fish samples. The determined values were in good agreement with the certified values and the recoveries for the spiked samples were in the range of 84.5-96.8%.

Metal organic framework assisted in situ complexation for miniaturized solid phase extraction of organic mercury in fish and Dendrobium officinale.

Zirconium-based metal-organic frameworks, namely Zr-based MOF, was employed as adsorbent material in the miniaturized solid phase extraction of organic mercury compounds in food prior to capillary electrophoresis-diode array detector analysis. The synthesized adsorbent was characterized by different spectroscopic techniques. Parameters influencing the extraction and complexation of methylmercury chloride, ethylmercury chloride and phenylmercury chloride such as type of eluent solvent, type and amount of adsorbent were investigated. In addition, linear ranges contained 2.00-300.00 ng mL-1 for MeHg+, 5.00-500.00 ng mL-1 for EtHg+ and PhHg+, and the established method presented good linearity (R2 ≥ 0.998). Under the optimized experimental conditions, the ranges of detection limit and quantitation limit were 0.022-0.067 ng mL-1 and 0.073-0.220 ng mL-1, respectively. The relative standard deviations of intra- and inter-day analysis were less than 3.2 and 3.1%, respectively. Trueness of the present method was successfully accomplished by means of the recovery assays (81.4-98.5%) in the blank samples with two concentration levels. The repeatability %RSD of the method was lower than 2.7%. Overall, the developed approach proved to have the latent capability to be utilized in routine analysis of organic mercury compounds in fish and Dendrobium officinale.

Isolation of methylmercury using distillation and anion-exchange chromatography for isotopic analyses in natural matrices.

The development of mercury (Hg) stable isotope measurements has enhanced the study of Hg sources and transformations in the environment. As a result of the mixing of inorganic Hg (iHg) and methylmercury (MeHg) species within organisms of the aquatic food web, understanding species-specific Hg stable isotopic compositions is of significant importance. The lack of MeHg isotope measurements is due to the analytical difficulty in the separation of the MeHg from the total Hg pool, with only a few methods having been tested over the past decade with varying degrees of success, and only a handful of environmentally relevant measurements. Here, we present a novel anion-exchange resin separation method using AG 1-X4 that further isolates MeHg from the sample matrix, following a distillation pretreatment, in order to obtain ambient MeHg stable isotopic compositions. This method avoids the use of organic reagents, does not require complex instrumentation, and is applicable across matrices. Separation tests across sediment, water, and biotic matrices showed acceptable recoveries (98 ± 5%, n = 54) and reproducible δ202Hg isotope results (2 SDs ≤ 0.15‰) down to 5 ng of MeHg. The measured MeHg pools in natural matrices, such as plankton and sediments, showed large deviations from the non-speciated total Hg measurement, indicating that there is an important isotopic shift during methylation that is not recorded by typical measurements, but is vital in order to assess sources of Hg during bioaccumulation. Graphical abstract.

Mercury removal from municipal secondary effluent with hydrous ferric oxide reactive filtration.

This study evaluated the ability of hydrous ferric oxide reactive filtration (HFO-RF) to remove mercury (Hg) from municipal secondary effluent at four study sites. Pilot HFO-RF systems (136 m3 /day) at two sites demonstrated total Hg concentration removal efficiencies of 96% (inflow/outflow mean total Hg: 43.6/1.6  ng/L) and 80% (4.2/0.8 ng/L). A lightly loaded medium-scale HFO-RF system (950 m3 /day) had a concentration removal efficiency of 53% (0.98/0.46 ng/L) and removed 0.52 mg/day of total Hg and 2.2 µg/day of methyl-Hg. A full-scale HFO-RF system (11,400 m3 /day) yielded a total Hg concentration removal efficiency of 97% (87/2.7 ng/L) and removed an estimated 0.36 kg/year of Hg. Results suggest that the quality of secondary effluent, including dissolved organic matter content, affects achievable minimum total Hg concentrations in effluent from HFO-RF systems. Low HFO-RF effluent concentrations (<1 ng/L) can be expected when treating secondary effluent from suspended-growth biological treatment systems. PRACTITIONER POINTS: Trace levels of mercury in municipal secondary effluent can negatively impact receiving waters. Hydrous ferric oxide reactive filtration (HFO-RF) can remove mercury from municipal secondary effluent to levels below the Great Lakes Initiative discharge standard of 1.3 ng/L. Mercury removal to low concentrations (< 1 ng/L) using HFO-RF appears to be associated with secondary effluents with low dissolved organic matter content. HFO-RF can also remove total phosphorus and turbidity to low concentrations.

Speciation of mercury in water and biological samples by eco-friendly ultrasound-assisted deep eutectic solvent based on liquid phase microextraction with electrothermal atomic absorption spectrometry.

A simple, fast, sensitive and eco-friendly ultrasound-assisted deep eutectic solvent liquid phase microextraction (UA-DES-LPME) was developed for preconcentration and speciation of Hg2+ and CH3Hg+ combined with ETAAS. Choline-phenol based DES (1:3, molar ratio) was used as an extractant for the determination of species of mercury, Hg2+ formed hydrophobic complexes with dithizone and complexes were then extracted using DES. For CH3Hg+ determination, CH3Hg+ can be extracted directly into DES phase because of its hydrophobic property. Under optimized conditions, the detection limits of Hg2+ and CH3Hg+ were 0.073 and 0.091 ng mL-1, respectively. %RSD (n = 7) were less than 4.1% and the enrichment factor (10 mL sample volume) were 34 and 18.3 for Hg2+ and CH3Hg+, respectively. The accuracy of the developed method was verified by analysis of SRM-1566b oyster tissue. The proposed method was applied to the speciation of mercury in several water and fresh water fish samples.

Use of an aminated Amberlite XAD-4 column coupled to flow injection cold vapour generation atomic absorption spectrometry for mercury speciation in water and fish tissue samples.

An aminated Amberlite XAD-resin as a solid phase extractant was tested for speciation of inorganic mercury, Hg(II) and methylmercury, MeHg(I) in water and fish tissue samples. It was found that Hg(II) and MeHg(I) ions could be simultaneously retained by a column filled with AAXAD-4 resin at pH 4 and the sequential quantitative elutions of Hg(II) and MeHg(I) were achieved using 10 mL of 0.1%(m/v) thiourea in 3%(v/v) HCl and 10 mL of 6 mol L-1 HCl, respectively. Hg(II) in the eluent was directly determined and MeHg(I) in the second eluent is quantified using FI-CVG-AAS after its oxidative digestion with KMnO4. The limits of detection for Hg(II) and MeHg(I) ions were found to be 0.148 and 0.157 µg L-1, respectively. The method was validated by analysing a certified reference material. The relative errors for Hg(II), MeHg(I) and T-Hg were in range of -1.8% and -3.2%.

Concentrations and health risks of inorganic arsenic and methylmercury in shellfish from typical coastal cities in China: A simultaneous analytical method study.

Shellfish consumption is an important pathway for coastal residents exposure to inorganic arsenic (iAs) and methylmercury (MeHg). An integrated method had been developed for simultaneous determination of iAs and MeHg in shellfish with microwave-assisted extraction and high performance liquid chromatography-inductively coupled plasma mass spectrometry identification. The limits of detection were 0.0520, 0.1003 and 0.0015 mg/kg (dry weight) for AsIII, AsV and MeHg, respectively. The proposed method was applied to evaluate the contents and health risks of iAs and MeHg in shellfish from the typical coastal cities (Lianyungang and Yantai) in China. The concentrations of iAs and MeHg in fresh shellfish were 0.10-1.69 mg/kg and 0.46-6.38 µg/kg, respectively. The target hazard quotient and target cancer risk values of iAs were the highest for the children and adults in Lianyungang, and were respectively larger than 1 and 1 × 10-4, indicating both non-carcinogenic and carcinogenic risks of iAs exposure were significant in this area.

Polyamide magnetic palygorskite for the simultaneous removal of Hg(II) and methyl mercury; with factorial design analysis.

A novel efficient adsorbent was prepared by the modification of magnetic palygorskite (MPG) by polyamide via the interfacial polymerization of trimesoyl chloride with m-phenylenediamine. The prepared magnetic palygorskite modified with polyamide (MPGP) material was appraised for its removal of the Hg(II) and CH3Hg species from aqueous solutions. The developed adsorbent was characterized using spectroscopic techniques. The adsorption ability of the MPGP sorbent was systematically investigated by using the batch method. Factorial design analysis was applied to study the effect of different batch parameters on the adsorption yield of both mercury species. These factors include mercury concentration, initial pH, sorbent amount and contact time. The equilibrium data coincided with the Langmuir adsorption isotherm indicating the maximum adsorption capacity of the MPGP was determined as 211.93 mg/g for Hg(II) and 159.73 mg/g for CH3Hg. The kinetic mechanism of the adsorption of both mercury species was well defined by the pseudo-second-order while the adsorption processes demonstrated spontaneity and an exothermic character at the studied temperatures. The cycling adsorption/desorption tests made by using a 1 mol/L HCl solution demonstrated that the MPGP had good reusable performance up to seven cycles. Based on the results it can be suggested that the synthesized MPGP sorbent can be handled for the elimination of Hg(II) and CH3Hg from wastewater effluents.

Ion-imprinted magnetic nanoparticles for specific separation and concentration of ultra-trace methyl mercury from aqueous sample.

For rapidly and sensitively determining ultra-trace methyl mercury (MeHg) in aqueous environment, we herein synthesized a MeHg ion-imprinted magnetic nanoparticle (MeHg IIMN) to simply and specifically extract/concentrate ultra-trace MeHg from water samples. The MeHg IIMN employed core-shell Fe3O4@SiO2 nanoparticles (Fe3O4@SiO2 NPs) as supporting structure, the complex ion of 1-pyrrolidinecarbodithioic acid and MeHg (PDC-CH3Hg+) as template, methacrylic acid (MAA) as functional monomer and trimethylolpropane trimethacrylate (TMPTM) as cross linker. The MeHg IIMN offered obvious advantages such as low cost, easy manipulation, better specificity and stability, and recycling characteristics. It can be used to separate/concentrate ultra-trace MeHg from natural water sample within 30min with a recovery >95%, an enrichment factor of 250, a relative standard deviation (RSD, n=5) <7%, a 25mg MeHg/g of maximum adsorption capacity, 50 times of recycling, and without obvious interference of other ions. Combining with capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS), it can be used for the accurate detection of ultra-trace methyl mercury in natural water samples with a limit of detection of 0.084pg/mL, a recovery of 92-99% and a RSD (n=5)<8%. The success of this study promises a valuable technique for relatively simple detection of ultra-trace methyl mercury in aqueous environment.

High removal efficacy of Hg(II) and MeHg(II) ions from aqueous solution by organoalkoxysilane-grafted lignocellulosic waste biomass.

An effective organoalkoxysilanes-grafted lignocellulosic waste biomass (OS-LWB) adsorbent aiming for high removal towards inorganic and organic mercury (Hg(II) and MeHg(II)) ions was prepared. Organoalkoxysilanes (OS) namely mercaptoproyltriethoxylsilane (MPTES), aminopropyltriethoxylsilane (APTES), aminoethylaminopropyltriethoxylsilane (AEPTES), bis(triethoxysilylpropyl) tetrasulfide (BTESPT), methacrylopropyltrimethoxylsilane (MPS) and ureidopropyltriethoxylsilane (URS) were grafted onto the LWB using the same conditions. The MPTES grafted lignocellulosic waste biomass (MPTES-LWB) showed the highest adsorption capacity towards both mercury ions. The adsorption behavior of inorganic and organic mercury ions (Hg(II) and MeHg(II)) in batch adsorption studies shows that it was independent with pH of the solutions and dependent on initial concentration, temperature and contact time. The maximum adsorption capacity of Hg(II) was greater than MeHg(II) which respectively followed the Temkin and Langmuir models. The kinetic data analysis showed that the adsorptions of Hg(II) and MeHg(II) onto MPTES-LWB were respectively controlled by the physical process of film diffusion and the chemical process of physisorption interactions. The overall mechanism of Hg(II) and MeHg(II) adsorption was a combination of diffusion and chemical interaction mechanisms. Regeneration results were very encouraging especially for the Hg(II); this therefore further demonstrated the potential application of organosilane-grafted lignocellulosic waste biomass as low-cost adsorbents for mercury removal process.

Epidemiological studies of neurological signs and symptoms and blood pressure in populations near the industrial methylmercury contamination at Minamata, Japan.

Severe methylmercury exposure occurred in Minamata, Japan. Only a limited number of epidemiological studies related to that exposure have been carried out. The evidence that methylmercury is cardiotoxic is very limited, and these studies provide only minimal support for that hypothesis. We therefore analyzed the data both from an investigation in Minamata and neighboring communities in 1971 and an investigation in 1974 in another area simultaneously. We included a total of 3,751 participants. We examined the association of residential area with neurological signs or blood pressure using logistic regression or multiple linear regression models, adjusting for sex and age. We found that the prevalence of neurological signs and symptoms was elevated in the Minamata area (high-exposure), followed by the Goshonoura area (medium-exposure). Moreover, blood pressure was elevated in residents of the Minamata area.

In situ selective determination of methylmercury in river water by diffusive gradient in thin films technique (DGT) using baker's yeast (Saccharomyces cerevisiae) immobilized in agarose gel as binding phase.

Saccharomyces cerevisiae immobilized in agarose gel as binding phase and polyacrylamide as diffusive layer in the diffusive gradient in thin films technique (DGT) was used for selective determination of methylmercury (MeHg). Deployment tests showed good linearity in mass uptake up to 48 h (3276 ng). When coupling the DGT technique with Cold Vapor Atomic Fluorescence Spectrometry, the method has a limit of detection of 0.44 ng L(-1) (pre concentration factor of 11 for 48 h deployment). Diffusion coefficient of 7.03 ± 0.77 × 10(-6) cm(2) s(-1) at 23 °C in polyacrylamide gel (pH = 5.5 and ionic strength = 0.05 mol L(-1) NaCl) was obtained. Influence of ionic strength (from 0.0005 mol L(-1) to 0.1 mol L(-1) NaCl) and pH (from 3.5 to 8.5) on MeHg uptake were evaluated. For these range, recoveries of 84-105% and 84-98% were obtained for ionic strength and pH respectively. Potential interference due to presence of Cu, Fe, Mn, Zn was also assessed showing good recoveries (70-87%). The selectivity of the proposed approach was tested by deployments in solutions containing MeHg and Hg(II). Results obtained showed recoveries of 102-115 % for MeHg, while the uptake of Hg(II) was insignificant. The proposed approach was successfully employed for in situ measurements in the Negro River (Manaus-AM, Brazil).

Synthesis of divinylbenzene polymer/Fe3O4 hybrid monolithic column for enrichment and online thermal desorption of methylmercury in real samples.

A novel method of divinylbenzene polymer (DVB)/Fe3O4 hybrid monolithic column solid phase extraction and on line thermal desorption was developed to analyze methylmercury (MeHg) in water and fish samples. The monolithic column was prepared by in situ polymerization in silica tube and its heating characteristic was studied in detail. Special accent was put on the study of parameters influencing adsorption and desorption of MeHg, such as pH, flow rate of sample solution, temperature of desorption and flow rate of carrier. Under optimum conditions, the detection limit and relative standard deviation of MeHg were 0.09 ng L(-1) and 2.6% (10 ng L(-1), N=11), respectively. Recoveries of MeHg were never less than 96%. Standard reference material GBW10029 was analyzed for validation of the methodology. This method was successfully applied to the determination of MeHg in water and fish samples.

Experimental dosing of wetlands with coagulants removes mercury from surface water and decreases mercury bioaccumulation in fish.

Mercury pollution is widespread globally, and strategies for managing mercury contamination in aquatic environments are necessary. We tested whether coagulation with metal-based salts could remove mercury from wetland surface waters and decrease mercury bioaccumulation in fish. In a complete randomized block design, we constructed nine experimental wetlands in California's Sacramento-San Joaquin Delta, stocked them with mosquitofish (Gambusia affinis), and then continuously applied agricultural drainage water that was either untreated (control), or treated with polyaluminum chloride or ferric sulfate coagulants. Total mercury and methylmercury concentrations in surface waters were decreased by 62% and 63% in polyaluminum chloride treated wetlands and 50% and 76% in ferric sulfate treated wetlands compared to control wetlands. Specifically, following coagulation, mercury was transferred from the filtered fraction of water into the particulate fraction of water which then settled within the wetland. Mosquitofish mercury concentrations were decreased by 35% in ferric sulfate treated wetlands compared to control wetlands. There was no reduction in mosquitofish mercury concentrations within the polyaluminum chloride treated wetlands, which may have been caused by production of bioavailable methylmercury within those wetlands. Coagulation may be an effective management strategy for reducing mercury contamination within wetlands, but further studies should explore potential effects on wetland ecosystems.

Rapid extraction and reverse phase-liquid chromatographic separation of mercury(II) and methylmercury in fish samples with inductively coupled plasma mass spectrometric detection applying oxygen addition into plasma.

A simple and sensitive procedure was developed for extraction and speciation of mercury in fish. Species separation was accomplished with reverse phase-high performance liquid chromatography (HPLC) hyphenated to inductively coupled plasma mass spectrometry (ICP-MS). Oxygen addition into plasma allowed use of organic-rich mobile phase, achieving species separation in 4 min. Mercury species extraction was achieved by microwave exposure for 2 min at mild conditions (60°C, pH 2.0), avoiding necessity of neutralizing sample prior to injection in HPLC, and reducing number of sample preparation steps, analytical source of errors and inter conversion of species. Limit of detection for entire procedure was found to be 0.2 and 0.1 ng g(-1) for mercuric ion and methylmercury, respectively. The method was applied to certified reference materials (TORT-2 and DORM-2) and commercialized fish samples (Mullus barbatus, Sparus aurata, Trachurus mediterraneus, Mugil soiuy, Dicentrarchus labrax, and Pomatomus saltatrix) from Black Sea.

Determination of methylmercury in marine sediment samples: method validation and occurrence data.

The determination of methylmercury (MeHg) in sediment samples is a difficult task due to the extremely low MeHg/THg (total mercury) ratio and species interconversion. Here, we present the method validation of a cost-effective fit-for-purpose analytical procedure for the measurement of MeHg in sediments, which is based on aqueous phase ethylation, followed by purge and trap and hyphenated gas chromatography-pyrolysis-atomic fluorescence spectrometry (GC-Py-AFS) separation and detection. Four different extraction techniques, namely acid and alkaline leaching followed by solvent extraction and evaporation, microwave-assisted extraction with 2-mercaptoethanol, and acid leaching, solvent extraction and back extraction into sodium thiosulfate, were examined regarding their potential to selectively extract MeHg from estuarine sediment IAEA-405 certified reference material (CRM). The procedure based on acid leaching with HNO3/CuSO4, solvent extraction and back extraction into Na2S2O3 yielded the highest extraction recovery, i.e., 94±3% and offered the possibility to perform the extraction of a large number of samples in a short time, by eliminating the evaporation step. The artifact formation of MeHg was evaluated by high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-MS), using isotopically enriched Me(201)Hg and (202)Hg and it was found to be nonexistent. A full validation approach in line with ISO 17025 and Eurachem guidelines was followed. With this in mind, blanks, selectivity, working range (1-800 pg), linearity (0.9995), recovery (94-96%), repeatability (3%), intermediate precision (4%), limit of detection (0.45 pg) and limit of quantification (0.85 pg) were systematically assessed with CRM IAEA-405. The uncertainty budget was calculated and the major contribution to the combined uncertainty (16.24%, k=2) was found to arise from the uncertainty associated with recovery (74.1%). Demonstration of traceability of measurement results is also presented. The validated measurement procedure was applied to the determination of MeHg incurred in sediments from a highly polluted and scarcely studied area in the Caribbean region.

Evaluación de la ingesta de pescado en población gestante en relación a la exposición al metilmercurio / Assesment of fish intake in pregnant population in relation to exposure to methylmercury

Introducción: El pescado es fuente importante de ácidos grasos poliinsaturados, fundamentales para el neurodesarrollo. Sin embargo, la contaminación con metilmercurio de algunas especies puede actuar en sentido contrario. Objetivo: Conocer la ingesta de pescado en las mujeres gestantes, así como el consumo de especies restringidas por los organismos internacionales por su contenido en metilmercurio y obtener información acerca de la educación sanitaria que reciben sobre las recomendaciones de ingesta de pescado y sus riesgos. Material y método: Se llevó a cabo un estudio descriptivo transversal de evaluación nutricional sobre la ingesta de pescado y marisco en 56 mujeres gestantes, mediante un cuestionario semicuantitativo de frecuencia de consumo. Asimismo, se evaluó el seguimiento de las recomendaciones de consumo de pescado. Resultados: Se obtuvo un consumo medio de pescado y marisco de 101g/día y una frecuencia de consumo medio de 5.53 raciones/semana. Un 91% de las mujeres cumplían las recomendaciones de la SECN, sin embargo un 25% excedían el consumo de especies no recomendadas por su contenido en metilmercurio según las recomendaciones de la AESAN y un 21.4% según recomendaciones de la Comisión Europea. Conclusiones: Las mujeres gestantes en este estudio, consumen pescado de forma adecuada en cantidad pero no siempre del tipo adecuado, excediendo el consumo de pescado azul con alto contenido en mercurio. Destaca la falta de conocimientos en relación al consumo recomendado de pescado y riesgos consecuencia de un déficit de educación sanitaria (AU)

Introduction: Fish is an important source of polyunsaturated fatty acids, which are essential for infant neurodevelopment. Nevertheless, the contamination of some species with methylmercury may act in opposite sense. Objective: To determine fish intake in pregnant population, as well as consumption of species restricted by international organisations because of their content in methylmercury, and to gather information about health education that women receive regarding fish intake recommendations and its possible risks. Materials and méthods: A cross-sectional study about nutritional evaluation of seafood intake was carried out in a sample of 56 pregnant women. Fish intake was assessed using a semiquantitative food frequency questionnaire. In addition, the meeting of the recommendations for fish consumption was analysed. Results: The average consumption of seafood was 101g/day, with a main frequency of 5,53 servings/week. 91% of the women met the recommendations given by the SECN. However, 25% and 21, 4% of pregnant women exceed the consumption of fish species with high methylmercury content in accordance with the AESAN and European Commission recommendations, respectively. Conclusions: Pregnant women in this study consumed fish frequently, but not always the correct kind, exceeding the consumption of oily fish high in mercury. It is important to note the lack of knowledge regarding the recommended fish consumption and its risks, due to a lack of health education (AU)

Polymer-supported ionic liquid solid phase extraction for trace inorganic and organic mercury determination in water samples by flow injection-cold vapor atomic absorption spectrometry.

A simple and green technique named polymer-supported ionic liquid solid phase extraction (PSIL-SPE) was developed for mercury (Hg) species determination. Inorganic Hg (InHg) species was complexed with chloride ions followed by its introduction into a flow injection on-line system to quantitatively retain the anionic chlorocomplex (HgCl4(2-)) in a column packed with CYPHOS(®) IL 101-impregnated resin. The trapped InHg was then reduced with stannous chloride (SnCl2) and eluted with the same flow of reducing agent followed by cold vapor atomic absorption spectrometry (CV-AAS) detection. Organic mercury species (OrgHg) did not interact with the impregnated resin and were not retained into the column. Total concentration of OrgHg was evaluated by difference between total Hg and InHg concentration. A 95% extraction efficiency was achieved for InHg when the procedure was developed under optimal experimental conditions. The limit of detection obtained for preconcentration of 40 mL of sample was 2.4 ng L(-1) InHg. The relative standard deviation (RSD) was 2.7% (at 1 µg L(-1) InHg and n=10) calculated from the peak height of absorbance signals (Gaussian-shape and reproducible peaks). This work reports the first polymer-supported IL solid phase extraction approach implemented in a flow injection on-line system for determination of Hg species in mineral, tap and river water samples.

Improvements and application of a modified gas chromatography atomic fluorescence spectroscopy method for routine determination of methylmercury in biota samples.

Improvements to the application of a combined solid-phase microextraction followed by gas chromatography coupled to pyrolysis and atomic fluorescence spectrometry method (SPME-GC-AFS) for methylmercury (MeHg) determination in biota samples are presented. Our new method includes improvements in the methodology of determination and the quantification technique. A shaker instead of a stirrer was used, in order to reduce the possibility of sample contamination and to simplify cleaning procedures. Then, optimal rotation frequency and shaking time were settled at 800 rpm and 10 min, respectively. Moreover, the GC-AFS system was equipped with a valve and an argon heater to eliminate the effect of the decrease in analytical signal caused by the moisture released from SPME fiber. For its determination, MeHg was first extracted from biota samples with a 25% KOH solution (3h) and then it was quantified by two methods, a conventional double standard addition method (AC) and a modified matrix-matched calibration (MQ) which is two times faster than the AC method. Both procedures were successfully tested with certified reference materials, and applied for the first time to the determination of MeHg in muscle samples of goosander (Mergus merganser) and liver samples of white-tailed eagle (Haliaeetus albicilla) with values ranging from 1.19 to 3.84 mg/kg dry weight (dw), and from 0.69 to 6.23 mg kg(-1) dw, respectively.