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Diffusive gradients in thin-films (DGT) is an in situ passive sampling technique to assess labile trace metal concentrations in different environmental matrix. The technique is consisting of a diffusive domain backed up by a resin gel that binds free metals and metal complexes that dissociate in the diffusive domain. This technique requires specific resin for special metals, for example mercury (Hg), since the classic resin (Chelex-100) gel is not applicable for Hg measurement. A simultaneous determination of Hg with other metals by the DGT was not yet reported. Two biomolecule-based resins were prepared by glutaraldehyde immobilisation of cysteine onto 3-amino-functionalised silica and 3-aminopropyl-functionalised silica, respectively. The load of functional groups on modified resins was qualitatively and quantitatively characterised. The modified resins were applied in the DGT technique and the uptake efficiency, elution efficiency, and linear accumulation of analytes of the DGT were tested. This novel DGT technique, using two cysteine-modified resins, can accumulate Hg and other metals in a broad range of pH and ionic strength in solutions. In the Belgian coastal zone (BCZ), the concentrations of Hg and other trace metals sampled by cysteine-modified resin-DGTs were similar as those by the other two DGT assemblies for Hg and other trace metals, respectively. The cysteine-modified silica resin combined the features of Chelex-100 resin and 3-mercaptopropyl silica resin and allowed simultaneous determination of labile Hg and other trace metals. The resin with a higher load of functional groups also showed higher performance in the further application in the DGT technique., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

3-Mercaptopropyl functionalized SBA-15 (SH-SBA) and 3-mercaptopropyl functionalized ethenylene bridged periodic mesoporous organosilica (SH-PMO) were included in a Diffusive Gradients in Thin film (DGT) probe and compared to similar commercially available resins also containing thiol functional groups, such as Sumichelate Q10R (SQR) and 3-mercaptopropyl functionalized silica gel (SH-KG), and also to the Chelex-100 resin for the determination of labile Hg concentrations. An agarose gel was used as the diffusive gel because the classic polyacrylamide gel shows more than 20% of Hg adsorption. According to our results, the Chelex-100 resin presents a much lower affinity for Hg than the thiol based resins. The non-linear accumulation profile of mercury with time for the Chelex-100 resin makes it in fact impossible to use Fick's law for estimating the diffusion coefficient of Hg. The 4 other resins all show a linear accumulation profile of Hg with time. Although the highest accumulation rate is observed for SH-PMO followed by SQR, SH-SBA and SH-KG, these values do not differ very much., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Total and methylmercury concentrations were assessed in muscle and liver of 141 fish samples from the northern part of the Persian Gulf. All fish samples belonged to five different species: grunt, flathead, greasy grouper, tiger-tooth croaker, and silver pomfret. In addition, Hg and methylmercury were analyzed in scalp hair of 19 fishermen living in the same coastal stations of the Persian Gulf and consuming several fish meals a week. Total mercury concentrations in fish muscle and liver ranged from 0.01 to 1.35 microg g(-1) w.w. and from 0.02 to 1.30 microg g(-1) w.w., respectively. In fish muscle, 3% of the Hg concentrations were higher than 0.5 microg g(-1) w.w., which corresponds to the maximum acceptable WHO level, while 9% were in the range of polluted fish (between 0.3 and 0.5 microg g(-1) w.w.). The highest mercury concentrations in fish muscle were observed in flathead fish at Abadan (average of 0.68 microg g(-1) w.w.). Methylmercury fractions in fish muscle and liver amount to 34-99% (median 64%) and 24-70% (median 43%), respectively. The mean total Hg concentration in the fishermen's scalp hair amounted to 2.9 +/- 2.2 microg g(-1), with 68% in the form of methylmercury. Ninety-five percent of the Hg levels in the fishermen's hair were below 10 microg g(-1), which is the WHO warning limit. In addition, relationships between the mercury levels in hair, on the one hand, and exposure-related factors such as Hg levels in specific fish species, regional differences, and number of fish meals, on the other hand, are discussed. It appears that a significant correlation for example exists between Hg levels human hair and fish muscle or human hair and age and that mean mercury levels in fish muscle and human hair decreased from western (Abadan) to eastern (Abbas port) coastal sites.

The concentrations of total mercury (Hg) and methyl mercury (MMHg) were determined in 78 marine sediments in the Iranian coastal waters of the Persian Gulf along nine transects perpendicular to the coastline. Total Hg ranged from 10 to 56 ng g( - 1)d.w. and MMHg from 0.1 to 0.4 ng g( - 1) d.w. The fraction of methyl mercury accounted from 0.3% to 1.1% of the total mercury amount. The organic carbon (OC) content ranged from 0.4% to 1.8%. The present study indicates that the levels of Hg in the sediments of the Iranian coast of the Persian Gulf were all in the concentration range of unpolluted areas regarding Hg (<100 ng g( - 1)). The concentrations of total Hg, methyl mercury and organic carbon were generally higher in the deeper stations. Total Hg and MMHg were significantly correlated, but no significant correlations could be found between the Hg and OC levels.

In order to understand the bioaccumulation of mercury in fish in the Iranian coastal waters of the Caspian Sea and the Persian Gulf, different fish species were sampled from both regions in January 2002. Mullet fishes were sampled from the Caspian Sea and six other species from the Persian Gulf: Largetooth flounder, Spotfin flathead, Japanese threadfin bream, Greater lizardfish, Elongate sole and Giant seacatfish. In the Persian Gulf, total Hg concentrations in fish ranged from 0.0123 to 0.0867 mg kg−1 w.w. (0.0614 to 0.433 mg kg−1 d.w.). Methylmercury accounts for 64–100% of the total mercury. Highest mercury concentrations were observed in the predatory fish: Giant seacatfish, Threadfin bream and the larger Greater lizardfish caught near Mogham Port. In these species the methylmercury fraction is always higher than 90%. A low methylmercury fraction was only observed in the smallest specimen of flounder and Elongate sole. In the Caspian Sea Hg concentrations in Mullet ranged from 0.0102 to 0.108 mg kg−1 w.w. The observed concentrations are comparable to those found in other areas of the Persian Gulf as well as in other marine environments and are much lower then the WHO guideline of 0.5 mg kg−1 w.w. [ABSTRACT FROM AUTHOR]

Abstract: Speciation of mercury compounds in environmental samples requires rigorous analytical procedures at each stage of sample collection, treatment and measurement. Sampling, the first step, is generally only critical for water samples. The best materials for water-sample storage and processing are Pyrex and Teflon (PTFE or FEP) after a severe cleaning procedure. Extraction of the Hg species from its matrix, the second step, requires an aggressive treatment, such as acid extraction (mostly combined with solvent extraction), distillation or alkaline extraction. Extraction is one of the most critical steps, and, for biota and sediments, almost certainly the most critical, because two conflicting issues need to be addressed – obtaining adequate recovery, and preventing losses. Extraction efficiency and validation are discussed as well as methylation artifacts, especially when the distillation method is applied to sediments. Separation of the Hg species, the third step, includes derivatization followed by gas chromatography (GC), new GC improvements and liquid chromatography (LC), which has, since the development of more sensitive detectors, resulted in wider applications in environmental studies. Detection of the Hg species is the fourth and last step in the analytical procedure. The development of commercial, relatively inexpensive, extremely sensitive, selective cold vapor atomic fluorescence spectrometry (CV-AFS) instrumentation in the late 1980s and 1990s made this the most popular detector for the laboratories working on the biogeochemical cycling of Hg. In recent years, the use of inductively coupled plasma mass spectrometry (ICP-MS) in speciation analysis has increased tremendously. Besides its high sensitivity and selectivity, ICP-MS offers the opportunity to perform speciated isotope dilution mass spectrometry (SID-MS). Finally, as other measurement fields, speciation analysis requires suitable reference materials to be available for the verification of accuracy and to meet quality-assurance needs. We also address these important aspects. [Copyright &y& Elsevier]

The analysis of mercury in food presents a challenge for analytical chemists. Sample pre-treatment and the preconcentration of mercury prior to measurement are required, even when highly sensitive analytical methods are used. In this work, the Diffusive Gradients in Thin Films technique (DGT), combined with thermal decomposition gold amalgamation atomic absorption spectrometry (TDA-AAS), was investigated for the determination of the total dissolved mercury in fish sauces. Moreover, a new type of binding gel with Purolite S924 resin was used in DGT. Linearity assays for DGT provided determination coefficients around 0.995. Repeatability tests showed a relative standard deviation of less than 10%. pH values in the range of 3–6, as well as NaCl concentrations up to 50 g·L−1, did not affect the performance of DGT. The effective diffusion coefficient of mercury in five-fold diluted fish sauce was determined to be (3.42 ± 0.23)·10−6 cm2·s−1. Based on the 24 h deployment time of DGT, the limit of detection (LOD) for the investigated method was 0.071 µg·L−1. The proposed method, which combines DGT and TDA-AAS, allows for the analysis of fish sauces with mercury concentrations below the LOD of TDA-AAS, and significantly reduces the wear and corrosion of the TDA-AAS components. [ABSTRACT FROM AUTHOR]