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1.
Determination of Zirconium and Vanadium in Natural Waters by Adsorptive Stripping Voltammetry in the Presence of Cupferron,Oxalic Acid and 1,3‐Diphenylguanidine
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Alexandre B. Schneider Paulo C. Nascimento Denise Bohrer Leandro M. de Carvalho Ananda Guarda Cristian Krause Bruna A. Wiethan Andrea Koschinsky 《Electroanalysis》2015,27(8):1864-1870
A sequential AdSV method based on the accumulation of Zr(IV) and V(V) as cupferron‐oxalic acid‐1,3‐diphenylguanidine (COD) complexes at the HMDE was used to determine traces of these metals in samples with different ionic strengths. DP mode, Eads ?0.6 and ?0.2 V (vs. Ag/AgCl, 3 mol L?1 KCl), tads 400 and 20 s and 10 and 60 mV s?1 scan rates were used for Zr(IV) and V(V), respectively. Epeak were ?0.95 (Zr(IV)‐COD) and ?0.65 V(V(V)‐COD). The methodology was applied in samples of rivers, estuaries (in Germany and Brazil) and coastal and open seawater. 相似文献
2.
Ismail Yilmaz 《Transition Metal Chemistry》2008,33(2):259-265
The new asymmetric, fluorescent Schiff-base ligand, N-(pyrene)-salicylaldimine (L), and its copper complex having an ONNO donor set, [Cu(L)
2
], were synthesized and characterized using elemental analysis, IR, UV-vis, 1H and 13C-NMR spectroscopies. Their electrochemical and spectroelectrochemical behaviors were investigated in a detail by using cyclic
voltammetry (CV), square wave voltammetry (SWV), in-situ UV-vis, and fluorescence spectroelectrochemistry. The formation of
the complex was monitored by the in-situ fluorescence technique based on the quenching of the fluorescence-probe ligand. Electrochemical
studies showed that L exhibits a single irreversible reduction process. However, the SWV indicated that this process was not totally irreversible
in the time scale of the measurement. The cathodic peak potential of the reduction process occurred at E
pc = −1.35 V vs Ag/AgCl (scan rate: 0.025 Vs−1). On the other hand, [Cu(L)
2
] showed one quasi-reversible one-electron reduction process in the scan rates of 0.025–0.50 Vs−1, which was assigned to metal-based one-electron process; [Cu(2+)(L)2] + e− → [Cu(+)(L)2]−. The value of half-wave potential (E
1/2) of the reduction process was −0.54 V vs Ag/AgCl (scan rate: 0.025 Vs−1). The time-resolved spectra showed, when the potential (E
app = −1.60 V) was applied in a thin-layer cell, that the main and shoulder bands of (L) at 385, 336, and 407 nm almost disappeared and a new band at 443 nm with a shoulder formed during the reduction process. No
change was observed on the final spectrum of the totally reduced ligand for long period under nitrogen atmosphere, which indicated
that the singly reduced species remained stable and was not accompanied by a chemical reaction in the time scale of the spectroelectrochemical
measurement. The spectral changes during the reduction process of [Cu(L)
2
] confirmed the metal-centered reduction process. The fluorescence intensity of L decreased during the reduction process in the thin-layer cell, as result of the perturbation of the conjugated system of
the reduced species. 相似文献
3.
In this paper we present a procedure allowing total-reflection X-ray fluorescence spectrometry (TXRF) determinations of arsenic in water samples, especially in seawater samples. The procedure consists of an arsenate reduction step (performed by using a l-cysteine solution) followed by a complexation of As+3 with sodium dibenzyldithiocarbamate and solid phase extraction. The new procedure is a modification of a method developed by Prange and allows a simultaneous determination of As together with V, Fe, Ni, Cu, Zn, Pb, and U in seawater by TXRF. The procedure was tested using the Certified Reference Material CASS-4 and was later applied to regular seawater samples collected from the North Sea. The detection limit for arsenic is 10 ng L− 1. 相似文献
4.
Turetta C Cozzi G Barbante C Capodaglio G Cescon P 《Analytical and bioanalytical chemistry》2004,380(2):258-268
Direct and simultaneous determination of Al, Ag, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Pb, Sb, U, V and Zn in diluted (1:10 v:v) seawater from the Antarctic Ocean and the Venice Lagoon at the ng mL–1 and pg mL–1 level has been performed by using an inductively coupled plasma sector field mass spectrometer (ICP-SFMS). Samples were analysed by using a PFA microflow nebulizer coupled with a desolvation system or a PFA microflow nebulizer coupled with a Teflon spray chamber, respectively. Measurements were carried out at low (LR, m/m=300), medium (MR, m/m=3,000) and high (HR, m/m=7,500) resolutions depending on the studied isotope. To avoid contamination, sample pre-treatment was carried out in a clean laboratory equipped with a Class 100 vertical laminar flow hood. Concentration ranges (minimum–maximum in ng mL–1) found in the Antarctic seawater samples (in depth profiles) were: Ag 0.0004–0.0018, As 0.69–1.32, Cd 0.031–0.096, Co 0.018–0.065, Cr 0.18–0.46, Cu 0.04–1.58, Fe 0.13–1.63, Mn 0.02–0.12, Mo 5.97–12.46, Pb 0.007–0.074, Sb 0.033–0.088, U 0.5–1.9, V 0.6–2.5 and Zn 0.16–0.80. Concentration ranges (min–max in ng mL–1) found in the Venice Lagoon water samples (temporal profile from a benthic chamber experiment) were: Al 0.24–0.61, Ag 0.007–0.031, As 1.42–2.27, Cd 0.050–0.182, Co 0.440–1.461, Cr 0.15–0.34, Cu 0.81–2.46, Fe 0.25–1.66, Mn 11.6–31.7, Mo 6.50–10.6, Pb 0.047–0.225, Sb 0.240–0.492, U 1.7–3.3, V 1.3–2.8 and Zn 5.20–21.5. The detection limits range between 0.06 pg mL–1 for Ag and U to 15 pg mL–1 for Fe. In order to check the accuracy of the analytical procedure, measurements of the trace elements in a certified reference material (coastal Atlantic seawater, CASS-4-NRCC) were compared with the certified values. In addition, the results from the Antarctic and Venice Lagoon samples were compared with those obtained by using different analytical techniques. 相似文献
5.
Y. Serfor-Armah C. M. Amoah G. T. Odamtten N. S. Opata E. H. K. Akaho 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(1):39-45
The Volta clam Galatea paradoxa is a highly priced shellfish providing nutrition, jobs and poverty alleviation for the inhabitants of the lower Volta estuary.
Clams are filter feeders straining particulate materials in the surrounding water, thus concentrating microorganisms and other
metal elements in the gut and mantle which present possible health hazards. The elemental composition of the water, clam mantle,
gut, shell, and bottom sediments were determined using Neutron Activation Analysis for the presence of Ca, Cl, Cu, Mg, Mn,
V, Fe, Co, Br, Na and K. Proximate analysis of the mantle for the levels of protein, fat, carbohydrate, ash, wood fiber, phosphorus,
free fatty acids and energy were carried out using the method of the Association of Official Analytical Chemists. The riverine
water was laden with heavy metals V, Co, Cu, Mn, and Fe, as well as Al. These same metallic elements were detected in higher
concentrations in the bottom sediments. Bioaccumulation factor (BAF) which is the measure of the distribution of heavy metals
between water and biota (Clam mantle and gut), ranged from 2 to 145 times, depending on the type of contaminant. The clam
meat contained high protein (15.3 ± 0.2%), no crude fiber, low fat content (1.80 ± 0.11%), fatty acids as oleic (25.2 ± 0.1%),
energy (85.5 ± 0.21 kcal/100 g), carbohydrates (22.10 ± 0.03%), P (485 ± 1 mg/100 g), Ca (793 ± 75 mg/kg), Mg (860.3 ± 90.0 mg/kg).
The high concentration of Ca (21,402.7 ± 797.0 mg/kg), Fe (18,071.2 ± 94.0 mg/kg), K (96 ± 14 mg/kg), Mg (540.8 ± 81.1 mg/kg),
Na (4,570.0 ± 0.2 mg/kg) gives credence to the use of the shell for poultry feed mineral supplements, and in the emulsion
paint manufacturing industry. 相似文献
6.
Abdel-Nasser M. A. Alaghaz Amani S. Alturiqi Reda A. Ammar Mohamed E. Zayed 《Phosphorus, sulfur, and silicon and the related elements》2019,194(1-2):47-56
The new cyclodiphosph(V)azane derivatives (1,3-dimethyl-2,4-dioxo-2',4'-bis(2,4-bis(dimethylaminopropylimino)cyclodiphosph(V)azane (H2L1) (1,3-dimethyl-2,4-dioxo-2',4'-bis(2,4-bis(dimethylaminoethylimino)cyclodiphosph(V)azane (H2L2) and (1,3-dimethyl-2,4-dioxo-2'-(dimethylaminoethylimino)-4'-(dimethylaminopropyl-imino)cyclodiphosph(V)azane (H2L3) containing four active coordination centers (NNNN) and their Cu(II) complexes have been synthesized and characterized by elemental analyses, spectroscopic methods, molar conductance as well as thermal and magnetic measurements. The UV–Vis and mass spectra of the ligands and their Cu(II) complexes were also recorded. The copper(II) complexes were found to have magnetic moments of 1.58–1.69 B. M. corresponding to one unpaired electron. The possible geometries of the complexes were assigned on the basis of EPR, electronic, and infrared spectral studies. The absence of water molecules in all complexes was supported by thermal studies. All the thermal decomposition processes ended with the formation of CuO. The kinetic and thermodynamic parameters have been calculated. The ligand (H2L3) and its Cu(II) complexes were screened for their anticancer studies against human breast cancer cell lines MCF-7 and minimum inhibitory concentration was calculated. The screening was extended to the antibacterial activity using Kirby–Bauer single disk susceptibility test for all compounds. 相似文献
7.
Alexandre B. Schneider Paulo C. Nascimento Denise Bohrer Leandro M. de Carvalho Ananda Guarda Daiane Dias Andrea Koschinsky 《Electroanalysis》2013,25(7):1628-1634
A voltammetric method was developed for zirconium determination as Zr(IV)‐cupferron‐oxalate‐diphenylguanidine complex based on adsorptive accumulation at the HMDE (Epeak=?0.95 V). The supporting electrolyte was a mixture of acetate/acetic acid (pH 4.6) and ammonium acetate (pH 5.7) solutions. Eads=?0.6 V (vs. Ag/AgCl), tads=400 s, 10 mV s?1 scan rate, and DP mode were the main parameters. The linear range was 0.033 to 3.3×10?9 mol L?1, and the LOD and LOQ (tads=400 s) were 0.77 and 1.6×10?11 mol L?1, respectively. The method was adequate for seawater samples, although not sufficiently sensitive for surface waters. 相似文献
8.
《Journal of Coordination Chemistry》2012,65(4):592-601
Reaction of 2-bromo-1,3-bis(bromomethyl)benzene (1) with 1,2,3-triazole and benzotriazole yields 2-bromo-1,3-bis(triazol-1-ylmethyl)benzene (2) and 2-bromo-1,3-bis(benzotriazol-1-ylmethyl)benzene (3), isolated as white solids, air stable at room temperature, and characterized by elemental analysis, mass spectra, IR, and NMR (1H, 13C) spectroscopy. The molecular structure of 3 was determined by single-crystal X-ray diffraction. These ligands were evaluated for determination of ultra-trace concentrations of nickel by adsorptive stripping voltammetry. The method is based on adsorptive accumulation of the Ni(II)-L complex onto a hanging mercury drop electrode, followed by reduction of the adsorbed species by voltammetric scan using square wave modulation. However, only with 2 was a signal observed at ?0.81?V. Under the best experimental conditions (pH 5.5; ligand concentration 0.30?μmol?L?1; adsorptive potential (E ads) ?0.70?V and adsorptive time (t ads) 80 s), the peak current is proportional to the Ni(II) concentration to 15.0?μg?L?1, with a 3 detection limit of 0.2?μg?L?1. The proposed method was validated by determining Ni(II) in certified reference waste water (SPS–WW1) with satisfactory results. 相似文献
9.
Milan Jakubek Zdeněk Kejík Robert Kaplánek Hana Veselá David Sýkora Pavel Martásek 《Supramolecular chemistry》2018,30(3):218-226
Perimidine-based chelators 1 and 2 were prepared, and their structures were confirmed by 1H and 13C NMR, MS spectroscopy and elemental analysis. These compounds were studied as specific synthetic receptors for the recognition of transition metal ions. They exhibited high affinity and selectivity towards Cu(II) ions. The conditional binding constants, linear dynamic range and detection limit were determined by UV–vis spectroscopy. These parameters demonstrated high potential of the prepared synthetic receptors for the recognition and determination of Cu(II) ions. The minimum detectable concentrations of Cu(II) ions for the synthetic receptors 1 and 2 were 270 and 75 nM (R 2 = 0.9915 and 0.9964) in aqueous medium (water/DMSO; 99:1 (v/v)), respectively. 相似文献
10.
Patrícia Pinto Maria J. Calhorda Vitor Félix Teresa Avilés Michael G. B. Drew 《Monatshefte für Chemie / Chemical Monthly》2000,3(4):1253-1265
The reaction between [Cu(NCMe)4][PF6] and 1,1′-bis-(diphenylphosphino)-ferrocene (dppf) in several ratios, solvents, and conditions led to the synthesis and structural characterization of the Cu(I) complexes [Cu(dppf)(Odppf)][PF6] (1), [(dppf)Cu(μ-dppf)Cu(dppf)][PF6]2 (2), and [(dppf)Cu(μ-Cl)2Cu(dppf)] (3). Although 1 and the cation in 2 were known, the first was structurally characterized for the first time, exhibiting a significant asymmetry in the coordination sphere of Cu(I) owing to the presence of oxygen. In 2, the PF6 − anion led to an interesting crystal packing with large open channels containing water. Finally, DFT calculations on a model of 3 showed that its HOMO exhibits, besides Fe, a significant Cu and Cl character, which is reflected in its electrochemical properties. 相似文献
11.
Patrícia Pinto Maria J. Calhorda Vitor Félix Teresa Avilés Michael G. B. Drew 《Monatshefte für Chemie / Chemical Monthly》2000,131(12):1253-1265
Summary. The reaction between [Cu(NCMe)4][PF6] and 1,1′-bis-(diphenylphosphino)-ferrocene (dppf) in several ratios, solvents, and conditions led to the synthesis and structural characterization of the Cu(I) complexes
[Cu(dppf)(Odppf)][PF6] (1), [(dppf)Cu(μ-dppf)Cu(dppf)][PF6]2 (2), and [(dppf)Cu(μ-Cl)2Cu(dppf)] (3). Although 1 and the cation in 2 were known, the first was structurally characterized for the first time, exhibiting a significant asymmetry in the coordination
sphere of Cu(I) owing to the presence of oxygen. In 2, the PF6
− anion led to an interesting crystal packing with large open channels containing water. Finally, DFT calculations on a model
of 3 showed that its HOMO exhibits, besides Fe, a significant Cu and Cl character, which is reflected in its electrochemical properties.
Received July 14, 2000. Accepted July 21, 2000 相似文献
12.
《Journal of Coordination Chemistry》2012,65(4):545-557
The coordination behavior of pyridine carbinoxide [NC5H4(CH2O)-2 or OPy] with copper in organic solvents was crystallographically determined. Initial attempts to generate the Cu(II) OPy derivatives from an alcoholysis exchange of Cu(OCH3)2, with H–OPy in toluene, led to the isolation of [Cu(µc-OPy)(OcPy)]2 (1, “c” indicates chelation). The square-based pyramidal geometries noted for each Cu center resulted from one OcPy and two µc-OPy ligands, generating an unusual Ci symmetry. From the reaction of H–OPy and the Cu(I) species Cu(C6H2(CH3)3-2,4,6), mononuclear Cu(II) complex Cu(OcPy)2(H–OPy)2 (2) was isolated. Compound 2 is unusual in that it adopts a square planar arrangement around the Cu metal center using two OcPy ligands; however, the metal center also coordinates with two H–OPy molecules forming an octahedral geometry. Upon dissolution in water, both 1 and 2 react to form the previously reported Cu(OcPy)2 · 2H2O (3). Attempts to add a Lewis base through dissolution of 1 in selected solvents (i.e., tetrahydrofuran, pyridine, 1-methylimidazole) led to [Cu(µc-OPy)(OcPy)]2 · H2O (4), which possesses a C 2 symmetry. The water was believed to be extracted from the “dry” solvents. A Cl derivative was also solved for the Cu(II)/Cu(I) species [Cu(OPy)2]2[CuCl(H–OPy)2]2 (5) from tetrahydrofuran dried over apparently contaminated sieves. 相似文献
13.
C. Menapace I. Lonardelli A. Molinari 《Journal of Thermal Analysis and Calorimetry》2010,101(3):815-821
New complexes of type [Cu(HTBG)2]Cl2 (1), [Cu(TBG)2]·3H2O (2) and [CuL]·nH2O (3) L:L1, n = 2 and (4) L:L2, n = 1 (HTBG: 2-tolylbiguanide, L1 and L2: ligands resulted from 2-tolylbiguanide, ammonia/hydrazine and formaldehyde one pot condensation) were synthesised and characterised.
The features of complexes have been assigned from microanalytical, IR and UV–Vis data. Redox behaviour was established by
cyclic voltammetry. The in vitro qualitative and quantitative antimicrobial activity assays showed that the complexes exhibited
variable antimicrobial activity against Gram-negative and Gram-positive strains isolated from the hospital environment. The
thermal analyses have evidenced the thermal intervals of stability and also the thermodynamic effects that accompany them.
After water elimination, complexes have a similar thermal behaviour. Processes as water elimination, melting, chloride anion
removal as well as oxidative degradation of the organic ligands were observed. The final product of decomposition was copper
(II) oxide. 相似文献
14.
《Journal of Coordination Chemistry》2012,65(13):1099-1123
Heteronuclear complexes containing oxorhenium(V), with Fe(III), Co(II), Ni(II), Cu(II), Cd(II) and UO2(VI) ions were prepared by the reaction of the complex ligands [ReO(HL1)(PPh3)(OH2)Cl]Cl (a) and/or [ReO(H2L2)(PPh3)(OH2)Cl]Cl (b), where H2L1?=?1-(2-hydroxyphenyl)butane-1,3-dione-3-(5,6-diphenyl-1,2,4-triazine-3-ylhydrazone) and H3L2?=?1-(2-hydroxyphenyl)butane-1,3-dione-3-(1H-benzimidazol-2-ylhydrazone), with transition and actinide salts. Heterodinuclear complexes of ReO(V) with Fe(III), Co(II), Ni(II), Cu(II) and Cd(II) were obtained using a 1?:?1 mole ratio of the complex ligand and the metal salt. Heterotrinuclear complexes were obtained containing ReO(V) with UO2(VI) and Cu(II) using 2?:?1 mole ratios of the complex ligand and the metal salts. The complex ligands a and b coordinate with the heterometal ion via a nitrogen of the heterocyclic ring and the nitrogen atom of the C=N7 group. All transition metal cations in the heteronuclear complexes have octahedral configurations, while UO2(VI)?complexes have distorted dodecahedral geometry. The structures of the complexes were elucidated by IR, ESR, electronic and 1H NMR spectra, magnetic moments, conductance and TG-DSC measurements. The antifungal activities of the complex ligands and their heteronuclear complexes towards Alternaria alternata and Aspergillus niger showed comparable behavior with some well-known antibiotics. 相似文献
15.
Leandro M. de Carvalho Paulo C. do Nascimento Denise Bohrer Raquel Stefanello Eduardo J. Pilau Marcelo B. da Rosa 《Electroanalysis》2008,20(7):776-781
This paper describes a new voltammetric procedure for the inorganic speciation of As(III) and As(V) in water samples. The procedure is based on the chemical reduction of arsenate [As(V)] to arsenite [As(III)] followed by the voltammetric determination of total arsenic as As(III) at the hanging mercury drop electrode (HMDE) by adsorptive cathodic stripping voltammetry (AdCSV) in the presence of sodium diethyl dithiocarbamate (SDDC). The reduction step involved the reaction with a mixture of Na2S2O5 and Na2S2O3 in the concentrations 2.5 and 0.5 mg mL?1, respectively, and the sample heating at 80 °C for 45 min. The linear range for the determination of total arsenic as As(III) in the presence of SDDC was between 5 and 150 μg L?1 for a deposition time of 60 s (r=0.992). A detection limit of 1.05 μg L?1 for total As was calculated for the method in water samples using a deposition time of 60 s. The detection limits of 4.2 μg L?1 and 15.0 μg L?1 for total As in seawater and dialysis concentrates, respectively, were calculated using a deposition time of 60 s. The relative standard deviations calculated were 2.5 and 4.0% for five measurements of 20 μg L?1 As(V) as As(III) in water and dialysis concentrates, respectively, after chemical reduction under optimized conditions. The method was applied for the determination of As(III) and total As in samples of dialysis water, mineral water, seawater and dialysis concentrates. Recovery values between 86.0 and 104.0% for As(III) and As(V) added to the samples prove the satisfactory accuracy and applicability of the procedure for the arsenic monitoring. 相似文献
16.
《Journal of Coordination Chemistry》2012,65(3):455-463
The ligand, N,N′-bis-(4-methoxy-benzylidene)-ethane-1,2-diamine (mb2en), and its corresponding copper(I) complexes, [Cu(mb2en)2]ClO4 (1), and [Cu(mb2en)(PPh3)2]BPh4 (2), have been synthesized and characterized by CHN analyses, 1H and 13C-NMR, IR, and UV-Vis spectroscopies. The crystal and molecular structure of [Cu(mb2en)2]ClO4 (1), were determined by X-ray crystallography from a single-crystal. The coordination polyhedron about copper(I) is best described as a distorted tetrahedron. Quasi-irreversible redox behavior was observed for 1 and 2 (E 1/2?=?0.55 and 0.95?V, respectively). 相似文献
17.
Seyed Ebrahim Hashemi Mahmood Payehghadr Zarrin Es'haghi Hadi Kargar 《International journal of environmental analytical chemistry》2013,93(12):1148-1163
ABSTRACTIn this approach, a new carbon paste electrode modified with N,N′-bis(5-bromo-2-hydroxybenzylidene)-2,2-dimethylpropane-1,3-diamine Schiff base ligand (L) was synthesised for selective and effective determination of Hg2+ ions in aqueous environmental samples using cyclic and square wave anodic stripping voltammetric methods. First, the selective detection of mercury ion was confirmed by evaluating the stability constants of metal complexes formed between the Schiff base ligand (L) and some desired cations by conductometric measurements. Afterwards, by preparing an effective carbon paste electrode modified with L, the experimental and instrumental parameters affecting the performance of modified electrode were investigated. Square wave anodic stripping voltammograms were obtained after applying an accumulation potential ?0.5 V and accumulation time 150 s in Britton–Robinson buffer solution at pH 2.0. The optimal square wave parameters found are pulse amplitude 75 mV, frequency 50 Hz and step potential 6 mV. The procedure exhibited linear range from 0.4 to 120 μg L?1 Hg2+ with a limit of detection of 0.042 μg L?1. The proposed electrode was proved to be highly selective in the presence of various cations and anions and was successfully used for determination of mercury in tobacco and several water samples. 相似文献
18.
An electrochemical adsorptive stripping approach is presented for the trace measurement of copper in some real samples. The method is based on the reduction of Cu2+ at pH 5.5 calcein blue (CB) containing solution at ?250 mV (vs. Ag/AgCl), adsorption of Cu? CB complex on hanging mercury drop electrode (HMDE) and the voltammetric determination by further reduction to Cu+ at HMDE. Experimental optimum conditions were determined in the fundamental studies. At the experimental optimum conditions the adsorbed complex of Cu2+ and calcein blue gives a well defined cathodic stripping peak current at ?0.135 V, which has been used for the determination of copper in the concentration range of 0.02 to 15 ng/mL with accumulation time of 90 s. The relative standard deviation (RSD) for the determination of 0.5 and 6.0 ng mL?1 were 2.60 and 1.94% respectively. (n=10). The method has been applied to the analysis of copper in analytical reagent grade salts and tap water, mineral water and drug samples with satisfactory results. 相似文献
19.
Hanyong Peng Nan Zhang Man He Beibei Chen 《International journal of environmental analytical chemistry》2016,96(3):212-224
A novel adsorbent of multi-wall carbon nanotubes (MWCNTs) chemically modified silica (MWCNTs-silica) was synthesised and employed as the adsorbent material for solid-phase extraction (SPE) of trace Zn(II), Cu(II), Cd(II), Cr(III), V(V) and As(V) in environmental water samples followed by inductively coupled plasma optical emission spectrometry detection. This material inherits the advantages of nanomaterial MWCNTs and conventional silica with dual functional groups (–NH2 and –COOH), and avoid the problem of nanomaterial in SPE, such as high pressure. The factors affecting the separation and preconcentration of target elements such as pH, sample flow rate and volume, eluent concentration and volume were investigated. Under the optimised conditions, the detection limits for Zn(II), Cu(II), Cd(II), Cr(III), V(V) and As(V) were 0.27, 0.11, 0.45, 0.91, 0.55 and 0.67 μg L?1 with the relative standard deviations of 3.1, 5.9, 4.1, 4.0, 7.3 and 8.6% (c = 10 μg L?1, n = 7), respectively. The adsorption capacity of MWCNTs-silica was 26.6, 70.0, 13.8, 58.0, 20.0 and 20.0 mg g?1 for Zn(II), Cu(II), Cd(II), Cr(III), V(V) and As(V), respectively, and the prepared adsorbent could be reused more than 100 times. In order to validate the developed method, two certified reference materials of GSBZ50009-88 and GSBZ 50029-94 environmental waters were analysed and the determined values were in good agreement with the certified values. The developed method has been applied to the determination of trace elements in environmental water samples with satisfactory results. 相似文献
20.
《Analytical letters》2012,45(13):1971-1985
Abstract Arsenic(V) [As(V)] was reduced to As(0) at pH 0.0 and As(III) at pH 4.5 on a carbon-paste electrode modified with hematite, which allowed their selective determination. Arsenic(V) suffered interference from copper (Cu) and bismuth (Bi). Arsenic(III) was almost free of them. Humic acid did not affect the signal of As(V) but increased the signal of As(III). Arsenic was preconcentrated at ?0.8 V for 100 s. The response was linear up to 70 µg L?1 for As(V) and 50 µg L?1 for As(III). The limits of detection were 2 µg L?1 and 5 µg L?1 respectively. This method was applied to drinking water and compost lixiviate. 相似文献