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1.
Experiments to determine the mercury methylation potential were performed on sediments from two locations on the river Idrijca
(Slovenia), differing in ambient mercury concentrations. The tracer used was the radioactive isotope 197Hg. The benefit of using this tracer is its high specific activity, which enables spikes as low as 0.02 ng Hg2+ g−1 of sample to be used. It was therefore possible to compare the efficiency of the methylation potential experiments over a
range of spike concentrations from picogram to microgram levels. The first part of the work aimed to validate the experimental
blanks and the second part consisted of several series of incubation experiments on two different river sediments using a
range of tracer additions. The results showed high variability in the obtained methylation potentials. Increasing Hg2+ additions gave a decrease in the percentage of the tracer methylated during incubation; in absolute terms, the spikes that
spanned four orders of magnitude (0.019–190 pg g−1 of sediment slurry) resulted in MeHg formation between 0.01 and 0.1 ng MeHg g−1 in Podroteja and Kozarska Grapa. Higher spikes resulted in slightly elevated MeHg production (up to a maximum of 0.27 ng g−1). The values of methylation potential were similar in both sediments. The results imply that the experimental determination
of mercury methylation potential strongly depends on the experimental setup itself and the amount of tracer added to the system
under study. It is therefore recommended to use different concentrations of tracer and perform the experiments in several
replicates. The amount of mercury available for methylation in nature is usually very small. Therefore, adding very low amounts
of tracer in the methylation potential studies probably gives results that have a higher environmental relevance. It is also
suggested to express the results obtained in absolute amounts of MeHg produced and not just as the percentage of the added
tracer. 相似文献
2.
A. A. Kamyshova A. Z. Kreindlin P. V. Petrovskii A. S. Peregudov Yu. A. Borisov A. A. Koridze 《Russian Chemical Bulletin》2005,54(12):2805-2812
The reaction of [Cp*2RuBr]+Br− with bromine in CH2Cl2 (CD2Cl2) in an inert atmosphere at room temperature produces the complexes [Cp*Ru(Br)C5Me4CH2Br]+Br3
− (syn conformer), [Cp*Ru(Br)C5Me3(CH2Br)2]+ (syn and anti conformers), and [Ru(Br)(C5Me4CH2Br)2]+ (syn conformer). All complexes were characterized by 1H and 13C NMR spectroscopy; the former complex, by elemental analysis. These complexes were also prepared by the reaction of [Cp*RuC5Me4CH2]+BF4
− with bromine in CH2Cl2.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2712–2718, December, 2005. 相似文献
3.
S. Pramanik S. S. Bhattacharyya P. Chattopadhyay 《Journal of Radioanalytical and Nuclear Chemistry》2007,274(2):237-243
A new stable chelating resin was synthesized by incorporating 2-aminothiophenol into Merrifield polymer through C-N covalent
bond and characterized by elemental analysis, IR and thermal study. The sorption capacity of the newly formed resin for Hg2+ as a function of pH has been studied using 203Hg radioisotope. The resin exhibits no affinity to alkali or alkaline earth metal ions and common anions. The separation of
mercury(II) in presence of different alkali and alkaline earth metal ions (Na+, K+, Mg2+, Ca2+, Sr2+, Ba2+), common anions (ClO4
−, SO4
2−) and other diverse ions (Ag+, Cu2+, Pb2+, Fe3+, Ni2+ and Zn2+) has been checked. In column operation it has been observed that Hg2+ content of the waste water can be removed at usual pH of natural water. Mercury was determined by isotope dilution method
and the concentration of Hg2+ in the waste water spiked with 203Hg was found to be 0.05 to 0.09 μg/ml. 相似文献
4.
Shangfen Gao Guangqun Tan Hongyan Yuan Dan Xiao Martin M. F. Choi 《Mikrochimica acta》2006,153(3-4):159-162
A simple and green analytical procedure based on chlorophyll a is presented for the determination of Hg2+ ion. Chlorophyll a was extracted and purified from the leaves of pea and is employed as a reagent for analysis of Hg2+ ion. It displays remarkable fluorescence emission at 674 nm when excited at 412 nm. The emission intensity decreased significantly
on exposure to various concentrations of Hg2+ ion. This forms the basis for the determination of Hg2+ ion. The proposed method was evaluated for sensitivity and selectivity. The linear concentration range was found to be 2.0–10 μM
with r2 = 0.997 and the limit of detection for Hg2+ ion was 1.3 μM. Ions including Pb2+, Cd2+, Ag+, Zn2+, Co2+, Ni2+, Cu2+, Mg2+, Mn2+, Ru3+, Er3+, K+, Na+, NH4+, Cl−, NO3−, CH3COO− and SO42− did not interfere with the measurement of Hg2+ ion even at 500-fold excess. Since chlorophyll a is widely available in the leaves of most plants, and the extraction and purification process is simple, this technique can
provide an alternative, sensitive and economical way to determine Hg2+ ion. 相似文献
5.
An analysis of the structures of minerals with [Hg2]2+ dumbbells including poyarkovite [Hg2]3Cl2O2, shakhovite [Hg2]2Sb(OH)3O3, vasilyevite Hg20O6I3Br2Cl(CO3), and kelyanite [Hg2]6[SbO6]BrCl2 was carried out. The determining factor in structure formation is the ordering of the centers of the cluster groups of mercury and large anions by systems of equidistant parallel planes with d hkl ~ 2.5–4.5 Å. The different combinations of atoms and fragments in the structure are ordered by their own pseudotranslation lattices; this probably reflects the stages of crystallization. The crystal structures under study are examples of balance between the local interatomic interactions and the forces that create long-range order for different stoichiometries, masses, and sizes of components. 相似文献
6.
A.K. Singh Puja Saxena Amit Panwar 《Journal of inclusion phenomena and macrocyclic chemistry》2006,54(3-4):299-305
Copper (II) complex of 2,4-dimethyl-1,5,9,12-tetraazacyclopentadeca-1,4-diene, [Me2(15)dieneN4] was synthesized and used in the fabrication of Cu2+ – selective ISE membrane in PVC matrix. The membrane having Cu(II) macrocyclic complex as electroactive material along with sodium tetraphenyl borate (NaTPB) as anion discriminator. Dibutyl phthalate (DBP) as plasticizer in poly(vinyl chloride) (PVC) matrix was prepared for the determination of Cu2+. The best performance was observed by the membrane having Cu(II) complex–PVC–NaTPB–DBP with composition 1:5:1:3. The sensor worked well over a concentration range 1.12 × 10−6 M–1.0 × 10−1 M between pH 2.1–6.2 and a fast response time 10±2 s and a lifetime of 6 months. Their performance in partially non-aqueous medium was found satisfactory. Electrodes exhibited excellent selectivity for Cu2+ ion over other mono-, di-, trivalent cations. It can also be used as indicator electrode in the potentiometric titration of Cu2+ against EDTA as well as in the determination of Cu2+ in real samples. 相似文献
7.
Abdolraouf Samadi-Maybodi S. Masoomeh Pourali Mohsen Tafazzoli 《Journal of solution chemistry》2009,38(2):159-169
27Al NMR spectroscopy is a powerful tool for the study of coordination and solvation in both aqueous and nonaqueous solutions.
In this study, the complexes coexisting upon dissolution of AlCl3 in acidic acetone + methanol solutions are shown to consist essentially of mixed hexacoordinated species of the general formula
[Al(CH3OH)6−n
(CH3COCH3)
n
]3+ (n=1,2 and 3), all exhibiting distinctly different 27Al shielding effects. The relative populations of the various mixed species are found to be highly dependent upon the acetone:methanol
mole ratio that in the more acetone-rich mixtures with aluminum become appreciably coordinated by acetone. The results demonstrate
that the key factor for the formation of acetone-containing species in acidic methanolic solutions is having the CH3COCH3:CH3OH mole ratio at 3:1. 相似文献
8.
The effects of La3+ on inward K+ channels at plasma membrane in vicia guard cells are investigated using the whole-cell patch-clamp recording mode. It is
shown that La3+ on both sides of plasma membrane blocks inward K+ currents in a concentration-dependent manner, indicating that La3+ binding sites may exist on both sides of plasma membrane in guard cells in vicia. The dose response is fitted by the Michaelis-Menten
relation characterized by an inhibitor constant K
i
of 2.56±0.25 μmol · L−1 (outside membrane) and (1.18±0.11)×10−15 mol · L−1 (inside membrane). Intracellular La3+ has much stronger inhibitory effect on inward K+ currents than extracellular La3+ does, suggesting there may exist stronger binding sites inside membrane than outside membrane. Since ion channel activities
of guard cells directly affect plant stomatal movement and water status, our results imply that rare earth elements might
have potential practical values in regulating plant water status and strengthening plant drought endurance. 相似文献
9.
The photoluminescence properties of xZnO–(100−x)SiO2 (x = 0, 5, 10, 20) containing 1% Eu2O3 prepared by a sol–gel method were systematically investigated. The results indicated that the relative proportion of f–f transitions to charge transfer (CT) absorption decreased with the increase of ZnO concentration. The intensity of 5D0–7FJ transitions of Eu3+ ions was enhanced with the increase of ZnO content due to local structure changes and decreased quantities of Eu3+ ions clusters. The results of fluorescence line narrow (FLN) spectra indicated that Eu3+ ions occupied one site in SiO2 glass and two sites in ZnO–SiO2 glasses. The second-order crystal field parameters were calculated. B20 and B22 for site 1 increased with excitation energy, while ones hardly changed for site 2. 相似文献
10.
WeiWei Fan Yan Lin XianZhong Zhang Yan Pang Cong Ma ZhiGang Tang JunBo Zhang XueBin Wang 《中国科学B辑(英文版)》2009,52(5):590-598
5-HT1A receptor is associated with a variety of pathophysiology of neuropsychiatric disorders. Accordingly, we have synthesized
a new 5-HT1A receptor ligand (HYNIC-MPP4) and labeled it with 99mTc using N-(2-hydroxyethyl)ethylenediaminetriacetic acid (HEDTA) as coligand. 99mTc-HEDTA/HYNIC-MPP4 was prepared under pH 6 at room temperature. Biodistribution of 99mTc-HEDTA/HYNIC-MPP4 in normal mice
showed that this complex had moderate brain uptake (0.60% ID·g−1 at 2 min p.i.) and good retention. The hippocampus had the highest radioactivity uptake at 2 min p.i. (1.84% ID⋆g−1). The ratio of Hipp/CB was 3.1 at 2 min p.i. and increased to 4.4 at 60 min p.i. After blocking with 8-hydroxy-2-(dipropylamino)
tetralin, the uptake of hippocampus was decreased significantly from 1.84% ID·g−1 to 0.53% ID·g−1 at 2 min p.i., while the cerebellum had no significant decrease. This 99mTc complex could be a potent agent for 5-HT1A receptor imaging.
Supported by the National Natural Science Foundation of China (Grant No. 20401004) and the Analysis and Test fund of Beijing
Normal University 相似文献
11.
A simple non-chromatographic method for the determination of mercury (Hg2+), methylmercury (MeHg+), dimethylmercury (Me2Hg), and phenylmercury (PhHg+) employing atomic fluorescence spectrometry (AFS) as detection technique was developed. Mercury species showed a particular behavior in the presence of several reagents. In a first stage SnCl2 was employed for Hg2+ determination; in a second step, [Hg2+ + PhHg+] concentration was determined using SnCl2 and UV radiation. MeHg+ decomposition was prevented adding 2-mercaptoethanol. In a third stage, [Hg2+ + PhHg+ + MeHg+] concentration was determined using K2S2O8. Finally, the four species were determined employing NaBH4. Reagents concentration and flow rates were optimized. The extraction technique of mercury species involved the use of 2-mercaptoethanol as ion-pair reagent. The limits of detection for Hg2+, PhHg+, MeHg+, and Me2Hg were 1, 40, 68, and 99 ng L−1 with a relative standard deviation of 1.5, 3.1, 4.7 and 5.8%, respectively. Calibration curve was linear with a correlation factor equal to 0.9995. The method was successfully applied to the determination of the mercury species in two Antarctic materials: IRMM 813 (Adamussium colbecki) and MURST-ISS-A2 (Antarctic Krill). 相似文献
12.
Silver (Ag) and gold (Au) nanoparticles impregnated in nylon membrane filters have been proposed as a new solid phase for preconcentration of mercury from natural waters. Water samples were treated with KMnO4 to convert all mercury species to inorganic Hg2+ and this was followed by the reduction of Hg2+ with NaBH4 to elemental Hg0. The determination of Hg was carried out by thermal evaporation of mercury from membrane filters using Zeeman mercury analyzer RA–915+ (Lumex, Russia). This process does not involve any additional sample treatment and sharply reduces risk of samples contamination. The limit of detection (LOD) was found to be 0.04 ng (absolute mass). Relative LOD was 0.4 ng L−1 for 100 mL of water. The method was validated through the analysis of CRM NRCC Tort–2 (Lobster hepatopancreas) and the found value (0.30 ± 0.07 μg g−1) was in good agreement with the certified value (0.27 ± 0.06 μg g−1). High efficiency of Hg accumulation from aqueous phase to membrane filters can be attributed to a large surface area of nanoparticles. 相似文献
13.
The mechanism of the spin-forbidden reaction Ti+(4F, 3d24s1) + C2H4→TiC2H2
+ (2A2) + H2 on both doublet and quartet potential energy surfaces has been investigated at the B3LYP level of theory. Crossing points
between the potential energy surfaces and the possible spin inversion process are discussed by means of spin-orbit coupling
(SOC) calculations. The strength of the SOC between the low-lying quartet state and the doublet state is 59.3 cm−1 in the intermediate complex IM1-4B2. Thus, the changes of its spin multiplicity may occur from the quartet to the doublet surface to form IM1-2A1, leading to a sig-nificant decrease in the barrier height on the quartet PES. After the insertion intermediate IM2, two distinct
reaction paths on the doublet PES have been found, i.e., a stepwise path and a concerted path. The latter is found to be the
lowest energy path on the doublet PES to exothermic TiC2H2
+(2A2) + H2 products, with the active barrier of 4.52 kcal/mol. In other words, this reaction proceeds in the following way: Ti++C2H4→4IC→IM1-4B2→4,2ISC→IM1-2A1→[2TSins]→IM2→[2TSMCTS]→IM5→TiC2H2
+(2A2)+H2.
Supported by ‘Qinglan’ Talent Engineering Funds by Tianshui Normal University. 相似文献
14.
Gibicar D Logar M Horvat N Marn-Pernat A Ponikvar R Horvat M 《Analytical and bioanalytical chemistry》2007,388(2):329-340
Because of increasing awareness of the potential neurotoxicity of even low levels of organomercury compounds, analytical techniques
are required for determination of low concentrations of ethylmercury (EtHg) and methylmercury (MeHg) in biological samples.
An accurate and sensitive method has been developed for simultaneous determination of methylmercury and ethylmercury in vaccines
and biological samples. MeHg and EtHg were isolated by acid leaching (H2SO4–KBr–CuSO4), extraction of MeHg and EtHg bromides into an organic solvent (CH2Cl2), then back-extraction into Milli-Q water. MeHg and EtHg bromides were derivatized with sodium tetrapropylborate (NaBPr4), collected at room temperature on Tenax, separated by isothermal gas chromatography (GC), pyrolysed, and detected by cold-vapour
atomic fluorescence spectrometry (CV AFS). The repeatability of results from the method was approximately 5–10% for EtHg and
5–15% for MeHg. Detection limits achieved were 0.01 ng g−1 for EtHg and MeHg in blood, saliva, and vaccines and 5 ng g−1 for EtHg and MeHg in hair. The method presented has been shown to be suitable for determination of background levels of these
contaminants in biological samples and can be used in studies related to the health effects of mercury and its species in
man. This work illustrates the possibility of using hair and blood as potential biomarkers of exposure to thiomersal. 相似文献
15.
Comparative quantum chemical calculations of structural parameters, chemical shifts of 11B NMR spectra, and atomic charges in 10-vertex boron hydride anions [1-CB9H10]− and [1-B10H9N2]− were performed using the restricted Hartree-Fock method with the 6-31++G(D,P) basis set.
Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1853–1855, September, 2007. 相似文献
16.
Changzhou Yuan Long Yang Linrui Hou Diankai Li Laifa Shen Fang Zhang Xiaogang Zhang 《Journal of Solid State Electrochemistry》2012,16(4):1519-1525
A facile hydrothermal strategy was first proposed to synthesize flower-like Co(OH)2 hierarchical microspheres. Further physical characterizations revealed that the flower-like Co(OH)2 microspherical superstructures were self-assembled by one-dimension nanobelts with rich mesopores. Electrochemical performance
of the flower-like Co(OH)2 hierarchical superstructures were investigated by cyclic voltammgoram, galvanostatic charge–discharge and electrochemical
impedance spectroscopy in 3 M KOH aqueous electrolyte. Electrochemical data indicated that the flower-like Co(OH)2 superstructures delivered a specific capacitance of 434 F g−1 at 10 mA cm−2 (about 1.33 A g−1), and even kept it as high as 365 F g−1 at about 5.33 A g−1. Furthermore, the SC degradation of about 8% after 1,500 continuous charge–discharge cycles at 5.33 A g−1 demonstrates their good electrochemical stability at large current densities. 相似文献
17.
Samuel Melaku Ilse Gelaude Frank Vanhaecke Luc Moens Richard Dams 《Mikrochimica acta》2003,142(1-2):7-12
Microwave digestion reduction-aeration and pyrolysis combined with cold vapour atomic absorption and cold vapour atomic fluorescence
are compared for the determination of total mercury in several biological and environmental matrices. The biological samples
were digested in a mixture of HNO3/H2O2, the environmental samples in a mixture of HNO3/HClO4. After reduction with SnCl2, the mercury was collected by two-stage gold amalgamation. After microwave digestion reduction-aeration, detection limits
of 1.4 ng g−1 and 0.6 ng g−1 were obtained for cold vapour atomic absorption spectrometry (CVAAS) and cold vapour atomic fluorescence spectrometry (CVAFS),
respectively, for 250 mg of environmental samples. For biological samples (500 mg) the detection limits were 0.7 ng g−1 (CVAAS) and 0.4 ng g−1 (CVAFS). After pyrolysis, detection limits of 3.5 ng g−1 and 1.6 ng g−1 for CVAAS and CVAFS, respectively, were obtained for a 10 mg sample. Pyrolysis can only be applied when the organic content
of the sample is not too high. Accurate results were obtained for 8 certified reference materials of both environmental and
biological origin. In addition, a real sludge sample was analysed.
Author for correspondence. E-mail: richard.dams@rug.ac.be
Received September 18, 2002; accepted December 3, 2002
Published online May 5, 2003 相似文献
18.
A coupling equation relating the quadrupole coupling constant (e2
Qq
zz
) to the asymmetry parameter (η) of the electric field gradient for a series of cobaltocenium derivatives (59Co NQR) is derived. The estimates of the correlation times of “slow” modulations of electron motions by tunneling processes
lie in the range from 10−12 to 10−14 s. This corresponds to the interval of the characteristic times of nuclear motions.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1919–1923, October, 2007. 相似文献
19.
Patel-Sorrentino N Benaim JY Cossa D Lucas Y 《Analytical and bioanalytical chemistry》2011,399(3):1389-1392
Total mercury (HgT) determination requires the addition of concentrated hydrochloric acid solution (≥10 mol L−1 HCl) in relatively high amounts to preserve the samples and to prepare reagent solutions. A method for the preparation of
concentrated HCl with HgT concentration of lower than 5 ng L−1 is described in this article. It is based on the well-known chemical reaction: 2 NH4Cl + H2SO4 → (NH4)2SO4 + 2 HCl. This method is validated thanks to the US Environmental Protection Agency method 1631 and standard reference materials
BCR-579 (mercury in coastal seawater). 相似文献
20.
Manfredo Hörner Gelson Manzoni de Oliveira Janaina Sartori Bonini Herton Fenner 《Journal of organometallic chemistry》2006,691(4):655-658
3-(2-fluorophenyl)-1-(3-nitrophenyl)triazene reacts with mercury(II) acetate in tetrahydrofuran in the presence of 2,2′-bipyridilamine to give yellow crystalline blocks of polymeric {HgII[NNN(PhR)2]2}n (R = NO2, F). The new triazenide complex belongs to the triclinic space group . In a molecule of {HgII[NNN(PhR)2]2} two deprotonated 1,3-diaryl-substituted triazenide ligands are coordinated in an opposite way to one Hg(II) ion by means of primary and secondary bonds. The Hg(II) ions are placed on the inversion centers of translation operated {Hg[NNN(PhR)2]2} moieties which are stacked along the crystallographic a-axis forming infinite unidimensional chains linked through metalocene alike Hg-η2,η2-arene π-interactions. 相似文献