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1.
Direct electrochemical determination of arsenate (AsV) in neutral pH waters is considered impossible due to electro-inactivity of AsV. AsIII on the other hand is readily plated as As0 on a gold electrode and quantified by anodic stripping voltammetry (ASV). We found that the reduction of AsV to AsIII was mediated by elemental Mn on the electrode surface in a novel redox couple in which 2 electrons are exchanged causing the Mn to be oxidised to MnII. Advantage is taken of this redox couple to enable for the first time the electrochemical determination of AsV in natural waters of neutral pH including seawater by ASV using a manganese-coated gold microwire electrode. Thereto Mn is added to excess (∼1 μM Mn) to the water leading to a Mn coating during the deposition of As on the electrode at a deposition potential of −1.3 V. Deposition of As0 from dissolved AsV caused elemental Mn to be re-oxidised to MnII in a 1:1 molar ratio providing evidence for the reaction mechanism. The deposited AsV is subsequently quantified using an ASV scan. AsIII interferes and should be quantified separately at a more positive deposition potential of −0.9 V. Combined inorganic As is quantified after oxidation of AsIII to AsV using hypochlorite. The microwire electrode was vibrated during the deposition step to improve the sensitivity. The detection limit was 0.2 nM AsV using a deposition time of 180 s. 相似文献
2.
Francesca Zavarise 《Analytica chimica acta》2010,668(2):177-4532
The preparation, characterization and analytical applications of gold electrodes modified with ω-mercapto alkyl/aryl sulfonates are described. The devices resulted effective for the determination of free and labile Pb(II) in water samples by anodic stripping voltammetry (Edep = −600 mV) and in particular 2-mercaptobenzimidazole-5-sulfonate (MBIS) offered the best performances with detection limit of 0.4 μg L−1.Quantitative stripping of Pb from the electrode surface during the anodic scan, is obtained using sodium citrate buffer (pH = 9.0) as supporting electrolyte. Natural waters were analysed by standard addition method with good recoveries (mean percentage = 97%); no fouling effects due to humic acids or other organic constituents were observed in the reported conditions. 相似文献
3.
Joby E. Joy Eric Atamanik Rohini Mani Abanti Nag R.M. Tiwari V. Thangadurai J. Gopalakrishnan 《Solid State Sciences》2010,12(12):1970-1976
We describe the synthesis, structures and dielectric properties of new perovskite oxides of the formula, Ba3MIIITiMVO9, for MIII = Fe, Ga, Y, Lu and MV = Nb, Ta, Sb. While MV = Nb and Ta oxides adopt disordered/partially ordered 3C perovskite structures where MIII/Ti/MV metal-oxygen octahedra are corner-connected, the MV = Sb oxides show a distinct preference for the 6H structure, where SbV/TiIV metal-oxygen octahedra share a common face forming (Sb,Ti)O9 dimers that are corner-connected to the MIIIO6 octahedra. The preference of antimony oxides (SbV:4d10) for the 6H structure – which arises from a special SbV–O chemical bonding that tends to avoid linear Sb–O–Sb linkages unlike NbV/TaV:d0 atoms which prefer ~180° Nb/Ta–O–Nb/Ta linkages – is consistent with the crystal chemistry of MV–O oxides in general. The dielectric properties reveal a significant difference among MIII members. All the oxides with the 3C structure excepting those with MIII = Fe show a normal low loss dielectric behaviour with ε = 20–60 in the temperature range 50–400 °C; the MIII = Fe members with this structure (MV = Nb, Ta) display a relaxor-like ferroelectric behaviour with large ε values at frequencies ≤1 MHz (50–500 °C). 相似文献
4.
Arsenic pollution of public water supplies has been reported in various regions of the world. Recently, some cancer patients are treated with arsenite (AsIII); most Japanese people consume seafoods containing large amounts of negligibly toxic arsenic compounds. Some of these arsenic species are metabolized, but some remain intact. For the determination of toxic AsIII, a simple, rapid and sensitive method has been developed using electrospray ionization mass spectrometry (ESI-MS). AsIII was reacted with a chelating agent, pyrrolidinedithiocarbamate (PDC, C4H8NCSS-) and tripyrrolidinedithiocarbamate-arsine, As(PDC)3, extracted with methyl isobutyl ketone (MIBK). A 1 μL aliquot of MIBK layer was directly injected into ESI-MS instrument without chromatographic separation, and was detected within 1 min. Arsenate (AsV) was reduced to AsIII with thiosulfate, and then the total inorganic As was quantified as AsIII. This method was validated for the analysis of urine samples. The limit of detection of As was 0.22 μg L−1 using 10 μL of sample solution, and it is far below the permissible limit of As in drinking water, 10 μg L−1, recommended by the WHO. Results were obtained in < 10 min with a linear calibration range of 1-100 μg L−1. Several organic arsenic compounds in urine did not interfere with AsIII detection, and the inorganic As in the reference materials SRM 2670a and 1643e were quantified after the reduction of AsV to AsIII. 相似文献
5.
Dr. Sruti Mondal Tanmoy Pain Dr. Marco Villa Dr. Sara Angeloni Dr. Arup Tarai Prof. Dr. Paola Ceroni Dr. Sanjib Kar 《欧洲无机化学杂志》2023,26(24):e202300283
The synthesis, structural, spectroscopic characterization, and DFT/TD-DFT calculations of antimony corroles are reported herein. The studied complexes can be described as [(Corr)SbIII] and [(Corr)(oxo)SbV]2, where Corr is the trianion of corrole. All these complexes are diamagnetic in nature as is evident from sharp peaks with normal chemical shifts in the 1H NMR spectra. Single crystal XRD analysis reveals that the antimony(V) corrole complex is the bis-μ-oxo-bridged dinuclear antimony(V). Both the tetra and hexa-coordinated [(Corr)SbIII] and [(Corr)(oxo)SbV]2 antimony complexes adopt domed-structure with weak d-π electron coupling. The Sb−O bond distances in the co-facial dimer of [(Corr)(oxo)SbV]2 are 1.9802(16) Å (DFT: 2.0141 Å ) (for Sb1−O1), and 1.9639(17) Å (DFT: 1.9957 Å ) (for Sb2−O2) respectively. We observed that even though iodosobenzene is frequently used to oxidize [(Corr)SbIII] species, the oxidation of [(Corr)SbIII] is indeed very facile in nature and it even occurred in the air-equilibrated CHCl3 solution while storing for few days. Excitation of these antimony (III/V) corrole complexes in DCM/MeOH (1 : 1) at 77 K results in red emission with maxima at 640–720 nm. The singlet oxygen production of [(Corr)(oxo)SbV]2 has a quantum yield of 69 % and is two times higher than the analogous [(Corr)SbIII] derivatives. 相似文献
6.
Tobias Schmidt 《Journal of solid state chemistry》2003,173(2):259-272
The title compounds were isolated in well-crystallized form from samples with a substantial excess of antimony, annealed at temperatures slightly below the melting point of that element. Their crystal structures were determined from single-crystal diffractometer data. Pr9-xSb21-y and Nd9-xSb21-y crystallize with a new monoclinic structure type, Pearson symbol mS(62-5.4), space group Cm, Z=2 with a=2859.1(4) pm, b=426.3(1) pm, c=1356.1(2) pm, β=95.52(1)°, R=0.034 for 4351 structure factors and 188 variable parameters for Pr9-xSb21-y and a=2845(2) pm, b=424.7(8) pm, c=1345.9(9) pm, β=95.42(7)°, R=0.069 for 2928 F values and 188 variables for Nd9-xSb21-y. Of the 30 atomic sites, three show fractional occupancy corresponding to the compositions Pr8.303(5)Sb20.03(1) and Nd8.30(2)Sb19.98(9), respectively. A model for the order of occupied atomic sites with a tripled b-axis is proposed resulting in the ideal compositions Pr5Sb12 and Nd5Sb12. The holmium compound Ho2Sb5 has a Dy2Sb5-type structure: mP28, P21/m, a=1301.8(3) pm, b=414.9(1) pm, c=1451.1(2) pm, β=102.14(1)°, R=0.028 for 2573 F values and 86 variables. In both structure types most rare earth atoms have nine antimony neighbors forming tricapped trigonal prisms. The coordination polyhedra of the antimony atoms show a great variety, with a trigonal prism of rare earth atoms as one extreme case. The other extreme coordination of an antimony atom is a distorted octahedron formed by six antimony atoms. The differences and similarities of both structures are discussed. Chemical bonding within the antimony polyanions is analyzed on the basis of an extended Zintl-Klemm concept using bond-length-bond-strength relationships. 相似文献
7.
A novel absorbent was prepared by dimercaptosuccinic acid chemically modifying mesoporous titanium dioxide and was employed as the micro-column packing material for simultaneous separation/preconcentration of inorganic arsenic and antimony species. It was found that both trivalent and pentavalent of inorganic As and Sb species could be adsorbed quantitatively on dimercaptosuccinic acid modified TiO2 within a pH range of 4–7, and only As(III) and Sb(III) could be quantitatively retained on the micro-column within a pH range of 10–11 while As(V) and Sb(V) were passed through the micro-column without the retention. Based on this fact, a new method of flow injection on-line micro-column separation/preconcentration coupled to inductively coupled plasma optical emission spectrometry was developed for simultaneous speciation of trace inorganic arsenic and antimony in natural waters. Under the optimized conditions, an enrichment factor of 10 and sampling frequency of 10 h− 1 were obtained with on-line mode. The detection limits of As(III), As(V), Sb(III), and Sb(V) are 0.53, 0.49, 0.77 and 0.71 ng mL− 1 for on-line mode and as low as 0.11, 0.10, 0.15 and 0.13 ng mL− 1 for off-line mode due to its higher enrichment factor (50), respectively. The relative standard deviations of two modes are less than 6.7% (C = 20 ng mL− 1, n = 7). The concentration ratio of lower oxidation states/higher oxidation states changing from 1:10 to 10:1 has no obvious effect on the recoveries of As(III) and Sb(III). In order to validate the developed method, two certified reference materials of GSBZ5004-88 and GBW(E)080545 water sample were analyzed and the determined values are in good agreement with the certified values. The proposed method was successfully applied to the simultaneous speciation of inorganic arsenic and antimony in natural waters. 相似文献
8.
An anion exchange HPLC-ICP-MS procedure allowing the simultaneous multielemental speciation analysis of arsenic, selenium, antimony and tellurium has been developed. Four arsenic species (AsIII, AsV, monomethylarsonic acid and dimethylarsinic acid), two selenium species (SeIV and SeVI) may be determined in a single run as well as one antimony (SbV) and one tellurium species (TeVI). Alternatively Sb and/or Te may be used as internal standards for As and Se speciation studies. Optimisation of ICP-MS conditions led to satisfactory relative (0.01 (SbV) to 1.8 (SeVI) ng ml−1) and absolute detection limits (1–180 pg). Reproducibility ranged from 3.1 to 5.6% and the linearity was verified in the 0–200 ng ml−1 range. 相似文献
9.
Carbon screen-printed electrodes (CSPE) modified with gold nanoparticles present an interesting alternative in the determination of antimony using differential pulse anodic stripping voltammetry. Metallic gold nanoparticles deposits have been obtained by direct electrochemical deposition. Scanning electron microscopy measurements show that the electrochemically synthesized gold nanoparticles are deposited in aggregated form. Any undue effects caused by the presence of foreign ions in the solution were also analyzed to ensure that common interferents in the determination of antimony by ASV. The detection limit for Sb(III) obtained was 9.44 × 10−10 M. In terms of reproducibility, the precision of the above mentioned method in %R.S.D. values was calculated at 2.69% (n = 10). The method was applied to determine levels of antimony in seawater samples and pharmaceutical preparations. 相似文献
10.
Abdeljalil Assoud 《Journal of solid state chemistry》2004,177(7):2249-2254
Ba4LaGe3SbSe13 was prepared by reacting the elements under exclusion of air at 700°C, followed by slow cooling to room temperature. It crystallizes in a new type of the monoclinic space group P21/c, with lattice dimensions of a=1633.30(9) pm, b=1251.15(7) pm, c=1303.21(7) pm, β=103.457(2)°, V=2590.0(2) 106 pm3 (Z=4). The structure contains isolated GeSe4 as well as Ge2Se7 digermanate units. Two of the latter are interconnected via an Sb2Se4 bridge yielding an almost linear complex anion [Ge2Se7-Sb2Se4-Ge2Se7]14−. The oxidation states are assigned to be BaII, LaIII, GeIV, SbIII, and Se−II, in accord with an electronically saturated nonmetal. The lone pair of SbIII reflects itself in highly irregular Se coordination. The red color of the material is indicative of semiconducting behavior with an activation energy of 2.0 eV. Electronic structure calculations based on the LMTO approximation point to a smaller gap, typical for this calculation method. We utilized the COHP tool to explore the bonding character of the different Sb-Se interactions. 相似文献
11.
Speciation of arsenic in ground water samples: A comparative study of CE-UV, HG-AAS and LC-ICP-MS 总被引:1,自引:0,他引:1
The performance of capillary electrophoresis-ultraviolet detector (CE-UV), hydride generation-atomic absorption spectrometry (HG-AAS) and liquid chromatography-inductively coupled plasma mass spectrometry (LC-ICP-MS) have been compared for the speciation of arsenic (As) in groundwater samples. Two inorganic As species, arsenite (AsIII), arsenate (AsV) and one organo species dimethyl arsenic acid (DMA) were mainly considered for this study as these are known to be predominant in water. Under optimal analytical conditions, limits of detection (LD) ranging from 0.10 (AsIII, AsT) to 0.19 (DMA) μg/l for HG-AAS, 100 (AsIII, DMA) to 500 (AsV) μg/l for CE-UV and 0.1 (DMA, MMA) to 0.2 (AsIII, AsV) μg/l for LC-ICP-MS, allowed the determination of the above three species present in these samples. Results obtained by all the three methods are well correlated (r2 = 0.996*** for total As) with the precision of <5% R.S.D. except CE-UV. The effect of interfering ions (e.g. Fe2+, Fe3+, SO42− and Cl−) commonly found in ground water on separation and estimation of As species were studied and corrected for. Spike recovery was tested and found to be 80-110% at 0.5 μg/l As standard except CE-UV where only 50% of the analyte was recovered. Comparison of these results shows that LC-ICP-MS is the best choice for routine analysis of As species in ground water samples. 相似文献
12.
Synthesis, crystal structures, magnetic and electric transport properties of Eu11InSb9 and Yb11InSb9
Sheng-qing Xia Svilen Bobev Arif Ozbay Veronika Fritsch 《Journal of solid state chemistry》2007,180(7):2088-2094
Two new rare-earth metal containing Zintl phases, Eu11InSb9 and Yb11InSb9 have been synthesized by reactions of the corresponding elements in molten In metal to serve as a self-flux. Their crystal structures have been determined by single crystal X-ray diffraction—both compounds are isostructural and crystallize in the orthorhombic space group Iba2 (No. 45), Z=4 with unit cell parameters a=12.224(2) Å, b=12.874(2) Å, c=17.315(3) Å for Eu11InSb9, and a=11.7886(11) Å, b=12.4151(12) Å, c=16.6743(15) Å for Yb11InSb9, respectively (Ca11InSb9-type, Pearson's code oI84). Both structures can be rationalized using the classic Zintl rules, and are best described in terms of discrete In-centered tetrahedra of Sb, [InSb4]9−, isolated Sb dimers, [Sb2]4−, and isolated Sb anions, Sb3−. These anionic species are separated by Eu2+ and Yb2+ cations, which occupy the empty space between them and counterbalance the formal charges. Temperature-dependent magnetic susceptibility and resistivity measurements corroborate such analysis and indicate divalent Eu and Yb, as well as poorly metallic behavior for both Eu11InSb9 and Yb11InSb9. The close relationships between these structures and those of the monoclinic α-Ca21Mn4Sb18 and Ca21Mn4Bi18 are also discussed. 相似文献
13.
The electrochemical processes of irreversibly adsorbed antimony (Sbad) on Au electrode were investigated by cyclic voltammetry (CV) and electrochemical quartz crystal microbalance (EQCM). CV data showed that Sbad on Au electrode yielded oxidation and reduction features at about 0.15 V (vs saturated calomel electrode, SCE). EQCM data indicated that Sbad species were stable on Au electrode in the potential region from −0.25 to 0.18 V (vs SCE); the adsorption of Sb inhibited the adsorption of water and anion on Au electrode at low electrode potentials. Sb2O3 species was suggested to form on the Au electrode at 0.18 V. At a potential higher than 0.20 V the Sb2O3 species could be further oxidized to Sb(V) oxidation state and then desorbed from Au electrode. 相似文献
14.
Dr. Chen Sun Dr. Zeyu Deng Zhiyuan Li Zhongwei Chen Xuanyu Zhang Dr. Jian Chen Prof. Dr. Haipeng Lu Prof. Dr. Pieremanuele Canepa Prof. Dr. Rui Chen Prof. Dr. Lingling Mao 《Angewandte Chemie (International ed. in English)》2023,62(10):e202216720
Hybrid organic–inorganic antimony halides have attracted increasing attention due to the non-toxicity, stability, and high photoluminescence quantum yield (PLQY). To shed light on the structural factors that contribute to the high PLQY, five pairs of antimony halides with general formula A2SbCl5 and A2Sb2Cl8 are synthesized via two distinct methods and characterized. The A2SbCl5 type adopts square pyramidal [SbCl5] geometry with near-unity PLQY, while the A2Sb2Cl8 adopts seesaw dimmer [Sb2Cl8] geometry with PLQY≈0 %. Through combined data analysis with the literature, we have found that A2SbCl5 series with square pyramidal geometry generally has much longer Sb⋅⋅⋅Sb distances, leading to more expressed lone pairs of SbIII. Additional factors including Sb−Cl distance and stability of antimony chlorides may also affect PLQY. Our targeted synthesis and correlated insights provide efficient tools to precisely form highly emissive materials for optoelectronic applications. 相似文献
15.
Aquation of the 1:2 complex between CrIII and nitrilotriacetic acid (NTA) was monitored using a combination of capillary electrophoresis (CE), ultraviolet–visible (UV–vis) spectrophotometry, and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. To our knowledge, this is the first published report of the use of either CE or ATR-FTIR to monitor the kinetics of ligand exchange reactions of CrIII–aminocarboxylate complexes. The aquation products were identified as the 1:1 CrIII complex with NTA and “free” NTA. The 1:1 complex dimerized to form a 2:2 complex in a slower subsequent reaction step. Rates of disappearance of the 1:2 complex were first-order under all experimental conditions. First-order rate constants for aquation, kobs (h−1), measured using all three techniques were similar at equivalent pH conditions, and with values reported previously in the literature. Measured kobs values exhibited a complicated pH dependence with three distinct regions: (i) at pH < 6.5, kobs values increased with decreasing pH, (ii) between pH 6.5 and 8.0, kobs values were relatively constant, and (iii) at 8.0 < pH < 10.0, kobs increased with increasing pH and then leveled off. A kinetic model incorporating five distinct aquation pathways was successfully employed to model the pH dependence of kobs from 0.0 < pH < 10.0. These results show that CE and ATR-FTIR can be used as tools for better understanding ligand exchange processes occurring in aqueous solution. 相似文献
16.
A new Zintl phase Ba3Ga4Sb5 was obtained from the reaction of Ba and Sb in excess Ga flux at 1000°C, and its structure was determined with single-crystal X-ray diffraction methods. It crystallizes in the orthorhombic space group Pnma (No. 62) with a=13.248(3) Å, b=4.5085(9) Å, c=24.374(5) Å and Z=4. Ba3Ga4Sb5 has a three-dimensional [Ga4Sb5]6− framework featuring large tunnels running along the b-axis and accommodating the Ba ions. The structure also has small tube-like tunnels of pentagonal and rhombic cross-sections. The structure contains ethane-like dimeric Sb3Ga-GaSb3 units and GaSb4 tetrahedra that are connected to form 12- and 14-membered tunnels. Band structure calculations confirm that the material is a semiconductor and indicate that the structure is stabilized by strong Ga-Ga covalent bonding interactions. 相似文献
17.
The Zintl phase Eu7Ga6Sb8 was obtained from a direct element combination reaction at 900°C. It crystallizes in the orthorhombic space group Pbca (No. 61) with a=15.6470(17) Å, b=17.2876(19) Å, c=17.9200(19) Å, and Z=8. In Eu7Ga6Sb8, the anionic framework forms infinite chains of [Ga6Sb8]14− which are arranged side by side to make a sheet-like arrangement but without linking. The sheets of chains are separated by Eu2+ atoms and also within the sheet, Eu2+ atoms fill the spaces between two chains. The chain is made up of homoatomic tetramers (Ga4)6+ and dimers (Ga2)4+ connected by Sb atoms. The compound is a narrow band-gap semiconductor with Eg∼0.6 eV and satisfies the classical Zintl concept. Extended Hückel band structure calculations confirm that the material is a semiconductor and suggest that the structure is stabilized by strong Ga-Ga covalent bonding interactions. Magnetic susceptibility measurements for Eu7Ga6Sb8 show that the Eu atoms are divalent and the compound has an antiferromagnetic transition at 9 K. 相似文献
18.
A detailed study of iron (III)–citrate speciation in aqueous solution (θ = 25 °C, Ic = 0.7 mol L−1) was carried out by voltammetric and UV–vis spectrophotometric measurements and the obtained data were used for reconciled characterization of iron (III)–citrate complexes. Four different redox processes were registered in the voltammograms: at 0.1 V (pH = 5.5) which corresponded to the reduction of iron(III)–monocitrate species (Fe:cit = 1:1), at about −0.1 V (pH = 5.5) that was related to the reduction of FeL25−, FeL2H4− and FeL2H23− complexes, at −0.28 V (pH = 5.5) which corresponded to the reduction of polynuclear iron(III)–citrate complex(es), and at −0.4 V (pH = 7.5) which was probably a consequence of Fe(cit)2(OH)x species reduction. Reversible redox process at −0.1 V allowed for the determination of iron(III)–citrate species and their stability constants by analyzing Ep vs. pH and Ep vs. [L4−] dependence. The UV–vis spectra recorded at varied pH revealed four different spectrally active species: FeLH (log β = 25.69), FeL2H23− (log β = 48.06), FeL2H4− (log β = 44.60), and FeL25− (log β = 38.85). The stability constants obtained by spectrophotometry were in agreement with those determined electrochemically. The UV–vis spectra recorded at various citrate concentrations (pH = 2.0) supported the results of spectrophotometric–potentiometric titration. 相似文献
19.
《Electrochemistry communications》2008,10(7):987-990
We report here a wall-jet electrogenerated iodine approach for sensitive detection of arsenite (AsIII) by using a disposable screen-printed ring disk carbon electrode. Iodide (I−) is first oxidized to iodine (I2) at the disk electrode; the electrogenerated I2 can be effectively reduced back to I− in the presence of AsIII. The inhibited reduction current of I2 to I− can thus be monitored at the ring electrode and used for AsIII analysis. Various factors influencing the flow injection analysis (FIA) of AsIII were thoroughly investigated in this study. Under the optimized conditions, a linear calibration plot up to 10 μM with a detection limit (S/N = 3) of 70 nM was obtained by using 50 μM KI as the mobile phase in FIA. Practical utility of the proposed method was demonstrated to detect AsIII in “Blackfoot” disease endemic village groundwater from southwestern coast area of Taiwan (Pei-Men). 相似文献