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CE methods for the speciation of inorganic and organomercury compounds are reviewed. Sample preparation, separation conditions and detection modes are discussed. Efficient separation and sensitive determination of mercury species by CE typically involves complexation with various thiols, chromogenic and other chelating agents; however, some methods do not require complexation. Spectrophotometric detection based on UV-visible absorption is by far the most commonly used. Hyphenated techniques, such as CE/inductively coupled plasma (ICP)-MS, hydride generation coupled to ICP-MS or atomic fluorescence spectrometry and CE/atomic absorption spectrometry are gaining popularity due to their high sensitivity and selectivity. Last, but not least, the potential and applications of electrochemical methods for detection of separated mercury species are outlined.

Contents of total mercury and mercury species (methylmercury – MeHg, inorganic mercury – Hg²⁺) were determined in four Moravian rivers – Jihlava, Becva, Loucka and Dyje (Czech Republic). Five tissues (muscle, gills, liver, kidney and skin) of chub (Leuciscus cephalus), zoobenthos, sediments and water samples were analyzed. Time stability of samples was also tested. The highest levels of total mercury were determined in muscle tissues of all tested fish. Relative contents of MeHg in muscle tissues of fish ranged from 83.6% to 92.0% of the total mercury contents. The relative contents of MeHg in sediments and in zoobenthos samples correlate very closely (correlation coefficient –0.83). A considerably lower content of MeHg (1.3–11.4%) was found in river sediments compared with lakes. A comparison of observed sampling sites (Vladislav, Hrubsice) proved the adverse effect of industrial contamination on the water ecosystem ofJihlavaRiver and incomplete removal of mercury species in a sewage station

Solvent extraction, sonication, and microwave-assisted extractions in the presence of extraction agents (thioacetic acid, citric acid, cysteine, 2-mercaptoethanol, HCl + NaCl, etc.) were tested for the isolation of mercury species. A mixture of 6 M HCl and 0.1 M NaCl was selected as the most suitable extraction agent. The extraction efficiency was about 10% higher and the RSD below 3.3% when microwave-assisted extraction was applied instead of sonication. The liquid chromatography-cold vapour atomic fluorescence spectrometry (LC/CV-AFS) method was optimised and used for separation and determination of inorganic mercury cations and alkylated and arylated mercury species. Isocratic elution at a flow rate of 0.15 mL/min (with a mobile phase containing 0.05% 2-mercaptoethanol (pH = 5) and 7% methanol and with a stepwise increase of methanol content up to 100% MeOH in the 15th min) was used for separation of mercury species on a Hypersil BDS C18 RP column. The limits of detection of the LC/CV-AFS system were estimated as 0.2 microg/L (3%) for MeHg+, 0.07 microg/L (5.3%) for inorganic Hg, 0.06 microg/L (3.4%) for PhHg+, and 0.12 microg/L (4.4%) for EtHg with the corresponding RSDs at 5 microg/L (n = 10) given in parentheses. The concentrations (2-10 mg/kg fresh weight) of total mercury and methylmercury (90-99% of the total mercury) in selected fish obtained by HPLC/CV-AFS were in good agreement (absolute deviations 0.05 mg/kg) but more precise (RSDs <5.4% at 5 mg/L, n = 10) than those determined by GC coupled to an electron capture detector. The RSDs (3.1-8.2% and 4.1-9.0%) of the overall analytical procedure for the determination of total mercury (AMA 254) and methylmercury (HPLC/CV-AFS) were determined for intra-day and inter-day assays, respectively.

An inductively coupled plasma mass spectrometry (ICP/MS) method was used for the evaluation of thallium transfer from naturally (pedogeochemically) and artificially contaminated soils into rape. Two sets of three different types of top soils (heavy, medium, and light) were used for pot experiments. The first set was collected from areas with high levels of pedogeochemical thallium (0.3, 1.5, and 3.3 mg kg(-1) DM). The second set of three soils with naturally low content of thallium was artificially contaminated with thallium sulfate to achieve five levels of contamination (0, 0.4, 2, 4, and 6 mg kg(-1) DM Tl). The soil samples and the samples of winter and spring rape (straw, seeds) from both sets were collected and analyzed. Plant and soil samples from fields were collected at 42 selected sites situated in South Bohemia and in Czech-Moravian Highlands where higher pedogeochemical content of thallium was expected. More intensive transport (better availability) of Tl was observed in the case of artificially contaminated soils. The physicochemical form and the total content of Tl in soil were found to be the main factors influencing its uptake by plants. The concentration of Tl in rapeseeds in the field samplings was mostly 45% of its content in the particular soil. Nevertheless the uptake of Tl from soils with naturally high pedogeochemical content can be high enough to seriously endanger food chains. These findings are very important because of the high toxicity of Tl and the absence of threshold limits for Tl in soils, agricultural products, feedstuffs, and foodstuffs in most countries including the Czech Republic.