Methylmercury in marine fish from Malaysian waters and its relationship to total mercury content

The study evaluated methylmercury concentrations, the methylmercury to total mercury ratio (%MeHg) and their correlations in ten fish species from different trophic levels. Methylmercury levels in fish studied were in the range of 0.007 to 0.914 µg g^?1 wet wt. Muscle tissue of predatory fish contained significantly (p < 0.05) higher content of methylmercury than non-predatory fish. The methylmercury to total mercury ratio ranged from 49.1% to 87.5%, with the highest ratio in predatory fish. This ratio was always higher in muscle tissue compared to the liver tissues, indicating tissue-specific binding and accumulation of methylmercury in the muscle. All the fish species showed strong positive correlation between methylmercury and total mercury levels (R ²> 0.86). Except for long tail tuna and short-bodied mackerel, all fish species showed lower methylmercury levels and estimated weekly intake as compared to the maximum values established by US FDA (of 0.5 µg g^?1) and by FAO/WHO (1.5 µg kg^?1 bodyweight), respectively. This study showed that the percentage of methylmercury is rather high in fish and fish represents the major source of this toxic mercury form to the local population.     

Determination of Arsenic,Mercury and Barium in Herbarium Mount Paper Using Dynamic Ultrasound-Assisted Extraction Prior to Atomic Fluorescence and Absorption Spectrometry

A dynamic ultrasound-assisted extraction method using Atomic Absorption and Atomic Fluorescence spectrometers as detectors was developed to analyze mercury, arsenic, and barium from herbarium mount paper originating from the herbarium collection of the National Museum of Wales. The variables influencing extraction were optimized by a multivariate approach. The optimal conditions were found to be 1% HNO₃ extractant solution used at a flow rate of 1 mL min^?1. The duty cycle and amplitude of the ultrasonic probe was found to be 50% in both cases with an ultrasound power of 400 W. The optimal distance between the probe and the top face of the extraction chamber was found to be 0 cm. Under these conditions the time required for complete extraction of the three analytes was 25 min. Cold vapor and hydride generation coupled to atomic fluorescence spectrometry was utilized to determine mercury and arsenic, respectively. The chemical and instrumental conditions were optimized to provide detection limits of 0.01 ng g^?1 and 1.25 ng g^?1 for mercury and arsenic, respectively. Barium was determined by graphite-furnace atomic absorption spectrometry, with a detection limit of 25 ng g^?1. By using 0.5 g of sample, the concentrations of the target analytes varied for the different types of paper and ranged between 0.4–2.55 µg g^?1 for Ba, 0.035–10.47 µg g^?1 for As, and 0.0046–2.37 µg g^?1 for Hg.     

Cadmium and Lead Distribution in Marine Soil Sediments,Terrestrial Soil,Terrestrial Rock,and Atmospheric Particulate Matter around Split,Croatia

The distributions of cadmium and lead in marine sediments, surrounding soil, stones, and atmospheric particulate matter were determined at different locations in Split, Croatia. The determination of cadmium and lead was performed by flame atomic absorption spectrometry whereas atmospheric particulate matter samples were analyzed by inductively coupled plasma–optical emission spectrometry. Cadmium concentrations in the stones and soil were between 0.2 to 0.6 µg g^?1 and 0.2 to 0.9 µg g^?1. The concentration in the atmospheric particulate matter were <0.2 µg m^?2 d^?1(detection limit) to 1.4 µg m^?2 d^?1. Lead concentrations in marine sediments, stones, soil, and atmospheric particulate matter ranged from 31.2 to 144.4 µg g^?1, 9.3 to 29.4 µg g^?1, 11.3 to 66.1 µg g^?1, and 0.5 to 241.4 µg m^?2 d^?1, respectively. The relationship between determined parameters was established using principal component analysis and the results are in agreement with the assumption that anthropogenic sources play important roles for lead and cadmium distribution.     

Determination of Heavy Metal Content in Wild-Edible Mushroom from Jordan

The heavy metal content was investigated for six mushroom species native to Jordan. Metal (Cu, Pb, Cd, Fe, Zn, Mn, Ni, and Co) content in soil substrate and their relation to metal concentrations in mushroom and underlying soil were determined by flame and graphite furnace atomic absorption spectrometry. Mushroom species and soil were collected from different places in Jordan. The highest Cu level was 51.84 µg g^?1 for the species Lepista nuda; whereas, the lowest Cu level was found to be 18.51 µg g^?1 in Calvatia utriformis. Among the wild mushrooms, the highest Pb level was found as 4.81 µg g^?1 in Bovista plumbea, whereas the lowest Pb concentration was 2.01 µg g^?1 in Calvatia utriformis. The highest Cd level was determined as 1.9 µg g^?1 for Lepista nuda, whereas the lowest Cd level was 0.58 µg g^?1 for the species of Polyporus frondosus. The highest Zn level was 58.77 µg g^?1 for the species of Lepista nuda and the lowest Zn concentration was found 35.98 µg g^?1 in Calvatia utriformis. The highest Fe level was found as 317 µg g^?1 in Lepista nuda, whereas the lowest Fe concentration was 211.7 µg g^?1 in Calvatia utriformis. The highest Mn content was 36.55 µg g^?1 for Russula delica, whereas the lowest Mn level was 24.5 µg g^?1 for the species Bovista plumbea. The highest Ni content was found as 12.65 µg g^?1 for Russula delica, whereas the lowest Ni level was 0.17 µg g^?1 for Bovista plumbea. The highest Co content in the tested mushrooms was found as 3.5 µg g^?1 for the species of Agaricus bisporus, whereas the lowest Co level was 0.85 µg g^?1 for Polyporus frondosus. The results indicated that, in general, heavy metal contents in all mushroom species were lower than the underlying soil substrates except for some mushroom species.     

Mercury Speciation in Fish by High-Performance Liquid Chromatography (HPLC) and Post-Column Ultraviolet (UV)-Photochemical Vapor Generation (PVG): Comparison of Conventional Line-Source and High-Resolution Continuum Source (HR-CS) Atomic Absorption Spectrometry (AAS)

An ultraviolet-photochemical generator (UV-PVG) capable of post-column on-line transformation of both organic and inorganic mercury species to cold vapor (Hg⁰) with subsequent detection by quartz tube-atomic absorption spectrometry (QT-AAS) was developed. Mercury(II), methylmercury(I), ethylmercury(I), and phenylmercury(I) were successfully detected after separation by reversed-phase high-performance liquid chromatography (RP-HPLC). Two types of AAS detectors were compared. The first was a commonly used line-source instrument while the second was a high-resolution continuum source (HR-CS) AAS. The latter provided better limits of detection: 0.47?µg?L^?1 for Hg(II), 0.84?µg?L^?1 for methylmercury(I), 0.80?µg?L^?1 for ethylmercury(I), and 2.0?µg?L^?1 for phenylmercury(I). The repeatability at 30?μg?L^?1 was 3.6%, 4.1%, 6.2%, and 4.5% for these species (n?=?10). These figures of merit were comparable with those reported for more sensitive atomic fluorescence spectrometry. Nine sample extraction procedures were investigated. Extraction by tetramethylammonium hydroxide and HCl at 75?°C was selected as the only method compatible with the proposed separation and detection steps providing high extraction efficiency and no changes in mercury speciation. The applicability of the proposed high-performance liquid chromatography–ultraviolet-photochemical vapor generation–quartz tube-atomic absorption spectrometry method was demonstrated using fish samples and certified reference materials (CRM) DOLT-4 (dogfish liver) and ERM-CE464 (tuna fish). The results were comparable to those obtained by a reference method based on L-cysteine extraction and high-performance liquid chromatography–inductively coupled plasma-mass spectrometry (HPLC–ICP-MS) determination.     

Mercury speciation by a high performance liquid chromatography—atomic fluorescence spectrometry hyphenated system with photo-induced chemical vapour generation reagent in the mobile phase

Speciation of mercury was accomplished by using a simple interface with photo-induced chemical vapour generation in a high performance liquid chromatography—atomic fluorescence spectrometry (HPLC-AFS) hyphenated system. Acetic acid and 2-mercaptoethanol in the mobile phase were used as photochemical reagent. The operating parameters were optimized to give limits of detection of 0.53 µg L^?1, 0.22 µg L^?1, 0.18 µg L^?1 and 0.25 µg L^?1 for inorganic mercury, methylmercury, ethylmercury and phenylmercury, respectively. The method was validated with the certified reference material DORM-2 and applied to the analysis of seafood samples. The HPLC-AFS hyphenated system is simple, environmentally friendly, and represents an attractive alternative to the conventional peroxothiosulfate-borohydride method.     

Simple mercury fractionation in biological samples by CV AAS following microwave-assisted acid digestion or TMAH pre-treatment

A simple and reliable method to determine total and inorganic mercury in biological certified reference material (CRM) by cold vapor atomic absorption spectrometry (CV AAS) is proposed. After the CRM treatment at room temperature with tetramethylammonium hydroxide (TMAH), inorganic mercury is determined by CV AAS. Total mercury is measured by the same technique, after sample acid digestion in a microwave oven. Organic mercury, basically methylmercury, is obtained by difference. In both procedures, the quartz tube is kept at room temperature. By means of analysis of the following reference materials: pig kidney, lobster hepatopancreas, dogfish liver and mussel tissue, it was clear that the difference between the total and inorganic mercury concentrations agrees with the methylmercury concentration. Only one calibration curve against aqueous standards in acidic medium was carried out for both procedures. The concentrations obtained by both procedures are in agreement with the certified values according to the t-test at a 95% confidence level. The relative standard deviations were lower than 3.0% for digested CRM and 6.0% for CRM treated with TMAH for most of the samples. The limits of detection in the samples were 0.02 µg g^− 1 and 0.04 µg g^− 1 for inorganic and total Hg, respectively, since the sample mass for total mercury was half of that for inorganic mercury determination. Simplicity and high efficiency without using chromatographic techniques are some of the qualities of the proposed method, being adequate for fractionation analysis of mercury in biological samples.     

Determination of traces of As,Cd, Cr,Hg, Mn,Ni, Sb,Se, Sn and Pb in human hair by triple quadrupole ICP-MS

With the wide range of metallic contaminants discharged in the environment, studying the human health requires a growing number of elements to be monitored in biological samples. Hair analysis has been suggested as a suitable tool for biomonitoring environmental and occupational exposure to toxic elements. This study describes a method for the determination of 10 trace elements in hair samples using ICP-QQQ-MS. Combining the power of the MS/MS high-energy Helium mode with the MS/MS O₂ mass-shift mode, the method offers great analytical performances with detection limits reaching 0.0014 µg g^?1 for As, 0.0016 µg g^?1 for Cd, 0.012 µg g^?1 for Cr, 0.0035 µg g^?1 for Hg, 0.0055 µg g^?1 for Mn, 0.10 µg g^?1 for Ni, 0.0012 µg g^?1 for Sb, 0.0083 µg g^?1 for Sn, 0.011 µg g^?1 for Se and Pb. The accuracy of the method was tested on a human hair ERM® certified reference material. Percent recoveries varied from 91.3% and 106.9% being always in the acceptance range of 90–110%. For all analysed elements, RSD% of repeatability ranged between 0.6% and 9.0% and those of intermediate precision did not exceed the limit of 20% being always lower than 10% (except for As). The proposed method was applied for the determination of trace elements in hair samples from 20 unexposed subjects. The geometric mean levels were as follows: Cr 0.28 µg g^?1, Mn 0.30 µg g^?1, Sn 1.04µg g^?1, Sb 0.07 µg g^?1, Hg 0.42 µg g^?1, As 0.02 µg g^?1, Cd 0.03 µg g^?1, Ni 0.51 µg g^?1, Se 0.45 µg g^?1 and Pb 1.83 µg g^?1. Element concentrations were in the same range with the reported data. The reported results may be useful for environmental exposure assessment or comparisons studies when establishing reference values of trace elements in exposed population.     

Determination of Rare Earth Elements in Navel Oranges from Different Geographical Regions of China by Inductively Coupled Plasma-Mass Spectrometry

There are three major production bases of navel oranges in China, including Southern Jiangxi Province, Southern Hunan Province, and the Three Gorges District of the Yangtze River. Southern Jiangxi and Southern Hunan are also famous for rare earth elements that are ionic, making them easily passed from soil to plants and fruits. To test the relative enrichment of rare earth elements in navel oranges from these production sites, ICP-MS analysis was performed following a microwave digestion procedure. The concentrations of La, Ce, Pr, and Nd in navel orange peels from Southern Jiangxi and Southern Hunan (1.26–1.86 µg g^?1) were much higher than results from the Three Gorges (0.23–0.46 µg g^?1). Moreover, yttrium is relatively enriched (0.25–0.29 µg g^?1) in navel orange peels from Southern Jiangxi at concentrations almost twice that from Southern Hunan (0.15 µg g^?1). The various concentrations and distribution of rare earth elements offers the possibility of traceability and authentication of navel oranges. Meanwhile, navel orange peels from Southern Jiangxi posed no risk in consumption, based on the maximum limit level (≤0.7 µg g^?1, wet weight) of rare earth elements in food issued in China (GB 2762-2005).     

Trace-level determination of pyrethroid,neonicotinoid and carboxamide pesticides in beeswax using dispersive solid-phase extraction followed by ultra-high-performance liquid chromatography-tandem mass spectrometry

The aim of the work was to develop an analytical procedure able to quantify traces of 13 neonicotinoids and pyrethroids as well as carboxamide in beeswax at low levels (ng g^?1) to evaluate the contamination. For this purpose, an efficient sample preparation procedure was developed based on solid–liquid extraction using dispersive diatomaceous earth and acetonitrile. This step was followed by a selective and sensitive analysis based on ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (ESI-MS/MS). This analytical procedure was validated based on International Conference on Harmonization guidelines. The limits of quantification ranged from 1 ng g^?1 (thiamethoxam, clothianidin, imidacloprid, acetamiprid, thiacloprid and boscalid) to 40 ng g^?1 (lambda-cyhalothrin). The method was then successfully applied to 60 samples of beeswax collected in several areas of France. The presence of thiacloprid, boscalid, imidacloprid and deltamethrin in beeswax was confirmed. The most frequently quantified pesticide was boscalid.     

Determination of Organic and Inorganic Mercury Species as Emetine Dithiocarbamate Complexes by High-Performance Liquid Chromatography with Electrogenerated Tris(2,2′-bipyridine)ruthenium(III) Chemiluminescence Detection

A sensitive method for simultaneous determination of organic and inorganic mercury species has been developed and is presented in this study. The method is based on complex formation of mercury species with the emetine dithiocarbamate (emetine-CS₂) ligand, HPLC separation, and tris(2,2′-bipyridine)ruthenium(III) chemiluminescence detection. The complexation reactions of the mercury species and emetine-CS₂ ligand occurred instantaneously upon the addition of emetine-CS₂ solution to the solution containing the mercury species. The complete separation of these complexes was achieved using an ODS column with 20 mM NaH₂PO₄-acetonitrile (52:48, v/v) containing 30 mM NaClO₄ as an ion-pair reagent. The calibration graphs of these complexes were linear in the range from 1–100 µg/L. The detection limits were 0.27 µg/L, 0.33 µg/L, 0.39 µg/L, and 0.17 µg/L for methylmercury, ethylmercury, phenylmercury, and the mercury ion, respectively, at a signal-to-noise ratio of 3. The developed technique was validated by analyzing certified reference materials, CRM7402-a (cod fish, NMIJ) and CE464 (tuna fish, ERM), in combination with sonication-assisted acid leaching and liquid-liquid extraction. The emetine-CS₂ ligand has been used for extraction, separation, and detection of mercury species. The results determined using the proposed method were in good agreement with the values of the certified reference materials. The MeHg⁺ and EtHg⁺ recoveries for the spiked samples were found to be almost 100%.     

Elemental Analysis of Phytotherapeutic Products by Inductively Coupled Plasma–Tandem Mass Spectrometry

A procedure for the determination of As, Cd, Cr, Ni, Pb, and V in phytotherapy medicines by inductively coupled plasma–tandem mass spectrometry is reported. The use of tandem mass spectrometry with oxygen into an octopole reaction system at various gas flow rates and the combination of on-mass and mass-shift modes was evaluated. Cadmium, Cr, Ni, and Pb were determined as free atomic ions while As and V were determined as the oxides AsO⁺ and VO⁺ in the same run. Samples were prepared by microwave-assisted digestion with dilute nitric acid and hydrogen peroxide. Two plant-certified reference materials (apple leaves and tomato leaves) were used to check the accuracy. For tandem mass spectrometry with 0.5?mL min^?1 O₂, recoveries in the 85–113% were typically obtained and no statistical differences were observed at the 95% confidence level (t-test) in comparison with the certified values. Using these conditions, the limits of detection for the method were 0.01, 0.0002, 0.008, 0.008, 0.003, and 0.002?µg g^?1 for As, Cd, Cr, Ni, Pb, and V, respectively. The procedure was used for the analysis of four phytotherapic drugs and the determined concentrations were up to 0.168?µg g^?1 As, 0.03?µg g^?1 Cd, 0.82?µg g^?1 Cr, 1.18?µg g^?1 Ni, 0.52?µg g^?1 Pb, and 2.4?µg g^?1 V with average precision values of 8% as the relative standard deviation. The found concentrations were compared with limits proposed in official guidelines and, in most cases, the values were below the maximum limits allowed.     

Determination of the Mineral Composition of Watercress and Data Evaluation Using Multivariate Analysis

This paper reports the determination of the mineral composition of watercress (Nasturtium officinale Cruciferae, Brassicaceae), grown in soils from three cities in the Bahia State of Brazil, and in a fourth city where plants were grown in a hydroponic system. The sampling was carried out during the summer and winter. Analyses were performed with inductively coupled plasma optical emission spectrometry (ICP OES), and the accuracy was confirmed with a certified reference material of apple leaves.

Principal component analysis (PCA) and hierarchical cluster analysis (HCA) revealed different mineral compositions of the samples collected in the summer and winter.

Samples collected in the summer had a higher concentration of the nutrients iron, calcium, and magnesium, and the samples collected in the winter had a higher concentration of manganese and copper. The average contents of the samples (expressed as wet weight) were 2.50 and 3.03 mg g^?1 for calcium, 0.37 and 0.86 mg g^?1 for magnesium, 8.68 and 10.84 µg g^?1 for iron, 8.42 and 8.47 µg g^?1 for zinc, 0.61 and 0.47 µg g^?1 for copper, and 7.78 and 5.03 µg g^?1 for manganese for summer and winter, respectively. These results are in agreement with values previously reported in the literature. Samples collected from the hydroponic system in the winter had a lower concentration of all nutrients.     

Identification and Quantification of Heterologous Compounds Parthenin and Organic Acids in Parthenium Hysterophorus L. Using HPLC-PDA-MS-MS

Parthenium hysterophorus L., is an obnoxious weed known for its environmental health hazards and medicinal uses. These characteristics are due to presence of sesquiterpene lactones and organic acids; therefore a rapid and sensitive analytical procedure using HPLC-PDA-MS-MS was developed and optimized for separation, identification, and quantification of parthenin and six organic acids. Separation and characterization of compounds was achieved on a RP-C18 column with 1% acetic acid in water (A) and acetonitrile (B) as a mobile phase at a flow rate of 0.6 mL min^?1 and by matching their UV and mass spectra with reference compounds. Six organic acids (ferulic acid, 0.1 mg g^?1 to coumaric acid, 13.6 mg g^?1) and parthenin (27.4 mg g^?1) were characterized within 26 minutes of chromatographic separation in plant extract. The calibration curves are linear with correlation coefficients from 0.985 to 0.998, limit of detection and quantification ranged between 1.0 µg mL^?1 (anisic acid) to 2.2 µg mL^?1 (parthenin) and 2.5 µg mL^?1 (coumaric acid) to 5.2 µ g mL^?1 (parthenin) and recovery ranged between 90.9% to 97.3%. To the best of our knowledge this is the first report for the simultaneous separation of parthenin and organic acids. The method is applicable for screening of commercial crops, medicinal plants, and their products which might be mixed with P. hysterophorus during harvesting period.     

The determination of methylmercury in biological samples by HPLC coupled to ICP‐MS detection

The use of high‐performance liquid chromatography (HPLC) coupled to inductively coupled plasma mass spectrometry (ICP‐MS) for the determination of methylmercury (MeHg⁺) in fish tissue and hair samples is described. Analysis of these sample types is required when carrying out biomonitoring studies to determine human dietary exposure to this toxic mercurial compound. The developed method used a mobile phase containing an organic modifier and a sulfydryl compound (1:1 v/v methanol:water containing 0.01% v/v 2‐mercaptoethanol) to limit peak tailing and aid separation. The chromatographic separation was coupled to the ICP‐MS detector via a short piece of PEEK tubing, attached to the nebulizer. A cooled spraychamber and oxygen addition post‐nebulization were required to limit the solvent loading on the plasma and reduce carbon build‐up on the cones, respectively. The sample preparation procedure employed a drying step followed by digestion of the sample using tetramethylammonium hydroxide (TMAH) and heating in an open vessel microwave system. Two fish tissue certified reference materials (CRM), tuna fish CRM 463 and 464 (BCR, Brussels), a tuna fish proficiency test sample, IMEP‐20 (IRMM, Geel, Belgium) and a hair CRM NIES no. 13 (National Institute of Environmental Science, Japan), were used to evaluate the method. The recovery of MeHg⁺ for these four materials was between 83 and 100%, with precisions better than 6% for three separate extractions of the different materials. The limit of quantitation for MeHg⁺ using the developed protocol was 0.5 µg Hg g^?1. The stability of MeHg⁺ in the fish sample extracts was also assessed and losses of 14–16% were observed after storage of the extracts in a refrigerator at 5 °C, in high‐density polypropylene tubes, for 6 months. The developed protocol has been used previously with atmospheric pressure ionization mass spectrometry (API‐MS) to provide structural characterization and also with calibration via isotope dilution (IDMS) to provide high accuracy quantitation. Copyright © 2006 John Wiley & Sons, Ltd.     

Mercury speciation in fish tissue by eco-scale thermal decomposition atomic absorption spectrometry: method validation and risk exposure to methylmercury

A non-chromatographic method for Hg speciation in fish muscle using eco-scale thermal desorption atomic absorption spectrometry was validated according to the demands of the Decisions 2007/333/EC, 2011/836/EC and 2002/657/EC. The method is based on the determination of total Hg in solid sample and MeHg⁺, respectively, after double liquid–liquid extraction (47% HBr, toluene, 1% l-cysteine) according to a procedure recommended by the European Commission. The method was applied for the speciation of Hg in fish muscle to asses the weekly intake and health risk exposure to MeHg⁺. The method provided calibration coefficients better than 0.999, limits of detection of 0.2 µg kg^?1 total Hg and 3.0 µg kg^?1 MeHg⁺. The accuracy of the method assessed by the analysis of CRMs was 100 ± 9% for total Hg and 101 ± 13% for MeHg⁺ for a coverage factor k = 2. The figures of merit of the method comply with the requirements in the European legislation. Total Hg in the analyzed fish species was in the range 12–108 µg kg^?1 wet mass, of which 83–97% as MeHg⁺. Although significant variation in total Hg was observed among fish species, no differences in terms of distribution of organic and inorganic Hg species were identified. No risk exposure to MeHg⁺ was ascertained from muscle fish consumption from reliable sources, since weekly intake was below 30% of provisional tolerable weekly intake of 1.6 µg kg^?1 body weight. Speciation is recommended as MeHg⁺ is much more helpful than total Hg to evaluate the dietary risk exposure.     

Pressurised fluid extraction of polycyclic aromatic hydrocarbons and their polar oxidation products from atmospheric particles

An effective method utilising pressurised fluid extraction (PFE) to simultaneously extract polycyclic aromatic hydrocarbons (PAHs) and their polar oxidation products from atmospheric particulate matter (PM) is presented. The PFE method is advantageous over the traditional Soxhlet extraction due to its lower solvent consumption (9 mL compared to 90 mL) and shorter extraction time (15 min versus 18 h). Seventy compounds including PAHs and polar PAH oxidation products containing carbonyl (oxy-PAHs), hydroxyl (hydroxy-PAHs), and carboxylic acid (carboxy-PAHs) groups were targeted in the extraction of two different PM matrices: wood smoke (WS) and diesel exhaust (DE) PM. The PFE method was optimised and then compared to Soxhlet extraction for both PM matrices. The overall amounts of PAHs and their derivatives extracted from WS PM were slightly higher for the optimised PFE method (1849 ± 21 and 1863 ± 25 µg g^?1 with dichloromethane (DCM) and methanol (MeOH), respectively) than those obtained with Soxhlet extraction (1726 ± 33 and 1769 ± 22 µg g^?1 with DCM and MeOH, respectively). For DE PM (standard reference material (SRM) 2975) the overall amounts extracted by both methods were similar (average of 165 ± 6 µg g^?1), agreeing with previously published values. The detailed evaluation of extraction efficiencies for WS PM showed similar amounts for unfunctionalised PAHs (1100 µg g^?1) for both methods and solvents. For DE PM the mass yields for PAHs using PFE with DCM (62 ± 1 µg g^?1) were the highest and nearly 20% higher than those obtained with MeOH (53 ± 2 µg g^?1). The total mass yields of carboxy and hydroxy-PAHs from WS PM were also similar (412 ± 18 and 407 ± 11 µg g^?1) for PFE and Soxhlet with MeOH, and higher than when DCM was used (371 ± 5 and 379 ± 12 µg g^?1 for PFE and Soxhlet, respectively). For both matrices, the PFE yields for oxy-PAHs were higher than those obtained with Soxhlet.     

Determination of arsenic species in a freshwater crustacean Procambarus clarkii

The arsenic species present in samples of the crayfish Procambarus clarkii caught in the area affected by the toxic mine‐tailing spill at Aznalcóllar (Seville, Southern Spain) were analyzed. The total arsenic contents ranged between 1.2 and 8.5 µg g^?1 dry mass (DM). With regard to the different species of arsenic, the highest concentrations were for inorganic arsenic (0.34–5.4 µg g^?1 DM), whereas arsenobetaine, unlike the situation found in marine fish products, was not the major arsenic species (0.16 ± 0.09 µg g^?1 DM). Smaller concentrations were found of arsenosugars 1a (0.18 ± 0.11 µg g^?1 DM), 1b (0.077 ± 0.049 µg g^?1 DM), 1c (0.080 ± 0.089 µg g^?1 DM), and 1d (0.14 ± 0.13 µg g^?1 DM). The presence of two unknown arsenic species was revealed (U1: 0.058 ± 0.058 µg g^?1 DM; U2: 0.12 ± 0.12 µg g^?1 DM). No significant differences were seen with respect to the total arsenic contents between the sexes. However, significant differences in the total arsenic contents were revealed between the area affected by the spill and the area not affected, the contents being greater in the affected area. Copyright © 2002 John Wiley & Sons, Ltd.     

Effect of Mercury(II) Traces on Catalytic Activity of Peanut and Horseradish Peroxidases

Abstract

Mercury(II) in the range of 0.1–1 µg L^?1 concentrations was found to be a much more efficient inhibitor of native peanut peroxidase (PNP) than of horseradish peroxidase (HRP) in the reaction of o‐dianisidine oxidation with hydrogen peroxide. The possible reason for the different degree of mercury(II) effects on the catalytic activity of both enzymes was studied. It was shown that the different number of glycans in PNP and HRP molecules (three and eight, respectively), or their absence in the molecule of wild‐type recombinant horseradish peroxidase refolded from E. coli inclusion bodies (recHRP), does not play a significant role in the effects caused by mercury(II). The efficient inhibition of PNP by mercury(II) in the absence of any other additives (for example, thiourea) originates from a greater mobility of the distal calcium ion in the enzyme molecule. A model scheme for the interaction of the studied plant peroxidases with mercury(II) was proposed. The PNP‐based enzymatic method for mercury(II) determination with c _min =0.04 µg L^?1 (0.2 nmol L^?1) was developed and the possibility of PNP application for analysis of different samples was demonstrated.     

Determination of mercury in tuna fish tissue using isotope dilution-inductively coupled plasma mass spectrometry

Isotope dilution-inductively coupled plasma mass spectrometry (ID-ICP/MS) was applied to determine mercury in living tissue. Microwave digestion method using HNO₃/H₂O₂ media for the dissolution of solid sample was studied. The procedure for accurate determination of total mercury in tuna fish tissue sample by ID-ICP/MS is described. For the method validation, total Hg concentration in tuna fish CRM (BCR CRM 463) was determined by ID-ICP/MS after addition of ²⁰²Hg to CRM followed by acid decomposition of the spiked sample. This method was applied to the determination of Hg in tuna fish CCQM-P39 sample provided by IRMM (Institute for Reference Materials and Measurement, GEEL, Belgium) for the international comparison study.