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1.
The capabilities and limitations of the continuous flow injection hydride generation technique, coupled to atomic absorption spectrometry, for the speciation of major antimony species in seawater, were investigated. Two pre-concentration techniques were examined. After continuous flow injection hydride generation and collection onto a graphite tube coated with iridium, antimony was determined by graphite furnace atomic absorption spectrometry. The low detection limits obtained (∼5 ng l−1 for Sb(III) and ∼10 ng l−1 for Sb(V) for 2.5 ml seawater samples) permitted the determination of Sb(III) and total antimony in seawater with the use of selective hydride generation and on-line UV photooxidation. The number of samples that can be analyzed is about 15 per hour for Sb(III) determinations and 10 per hour for total antimony determinations. The analysis of seawater samples showed that Sb(V) was the predominant species, even in the presence of important biological activity.  相似文献   

2.
A sensitive method is described for the determination of trace bismuth based on the bismuth-bromopyrogallol red (BPR) adsorption at a carbon paste electrode (CPE). The overall analysis involved a three-step procedure: accumulation, reduction, and anodic stripping. Optimal conditions were found to be an electrode containing 25% paraffin oil and 75% high purity graphite powder, a 0.30 mol l−1 HCl solution containing 2.0×10−5 mol l−1 BPR as supporting medium; accumulation potential and time, −0.10 V, 3 min; reduction potential and time, −0.35 V, 60 s; scan rate 100 mV s−1; scan range from −0.35 to 0.15 V. It was found that the Bi(III)-BPR complex could be accumulated on the electrode surface during the accumulation period. Then the Bi(III) in the Bi(III)-BPR complex on the CPE surface was reduced to Bi(0) during reduction interval and finally reoxidized during the anodic stripping step for voltammetric quantification. Factors affecting the accumulation, reduction, and stripping steps were investigated. Interferences by other ions were studied as well. The detection limit was found to be 5×10−10 mol l−1 with a 3 min accumulation time. The linear range was from 1.0×10−9 to 5.0×10−7 mol l−1. Application of the procedure to the determination of bismuth in water and human hair samples gave good results.  相似文献   

3.
Liquid-liquid extraction preconcentration technique which allows the achievement of extremely high ratio between the aqueous and organic phase was specified as semi-microextraction. A modified highly effective liquid phase semi-microextraction (LSME) procedure was developed for preconcentration and determination of ultra trace levels of inorganic antimony species in environmental waters using electrothermal atomic absorption spectrometry (ETAAS) for quantification. Antimony(III) species were selectively extracted as dithiocarbamate complexes from 100 mL aqueous phase into 250 μL xylene at pH range of 5-8. Total Sb was determined using the same extraction system over a sample acidity range of pH 0-1.2 without the need for pre-reduction of Sb(V) to Sb(III). The concentration of Sb(V) was obtained as the difference between that of total antimony and Sb(III). With an 8 min extraction an enrichment factor of 400 was achieved. The limit of detection (3 s) was 2 ng L−1 Sb. The method was not affected by the presence of up to 0.01% humic acid, 0.025 mol L−1 EDTA, 0.01 mol L−1 tartaric acid and 0.001 mol L−1 F. Recoveries of spiked Sb(III) and Sb(V) in river, tap, and sea water samples ranged from 93 to 108%. The results for total antimony concentration in the river water reference material SLRS-5 were in good agreement with the information value. The procedure was applied to the determination and quantification of dissolved antimony species in natural waters.  相似文献   

4.
Atomic fluorescence spectrometry was used as an element-specific detector in hybridation with liquid chromatography (LC) and hydride generation for the speciation of Sb(III), Sb(V) and trimethylantimony dichloride (TMSbCl2). The three species were poorly resolved in a single chromatogram but good results were obtained by anion-exchange chromatography, using a mobile phase with 20 mM EDTA and 8 mM hydrogenphthalate to separate Sb(III) and Sb(V) and 1 mM carbonate at pH 10 to separate Sb(V) and TMSbCl2. Calibration graphs were linear between 2 and 100 μg l−1. Detection limits were 0.9, 0.5 and 0.7 μg l−1 for Sb(III), Sb(V) and TMSbCl2, respectively. The method was applied to the speciation of antimony in environmental samples.  相似文献   

5.
An analytical procedure for determination of As(III) and As(V) in soils using sequential extraction combined with flow injection (FI) hydride generation atomic fluorescence spectrometry (HG-AFS) was presented. The soils were sequentially extracted by water, 0.6 mol l−1 KH2PO4 solution, 1% (v/v) HCl solution and 1% (w/v) NaOH solution. The arsenite (As(III)) in extract was analyzed by HG-AFS in the medium of 0.1 mol l−1 citric acid solution, then the total arsenic in extract was determined by HG-AFS using on-line reduction of arsenate with l-cysteine. The concentration of arsenate (As(V)) was calculated by the difference. The optimum conditions of extraction and determination were studied in detail. The detection limit (3σ) for As(III) and As(V) were 0.11 and 0.07 μg l−1, respectively. The relative standard deviation (R.S.D.) was 1.43% (n=11) at the 10 μg l−1 As level. The method was applied in the determination of As(III) and As(V) of real soils and the recoveries of As(III) and As(V) were in the range of 89.3-118 and 80.4-111%, respectively.  相似文献   

6.
This paper describes a procedure for the speciation of antimony by UV-vis spectroscopy using pyrogallol as complexing agent. A partial least squares (PLS) regression was performed to resolve highly overlapping spectrophotometric signals obtained from mixtures of Sb(III) and Sb(V). The relative error in absolute value was less than 5% when concentrations of several mixtures were calculated. The minimum concentration determined was 3.96 × 10−5 mol dm−3 and 3.98 × 10−5 mol dm−3 for Sb(V) and Sb(III), respectively. The analysis of the possible effect of the presence of foreign ions in the solution was performed and the procedure was successfully applied to the speciation of antimony in pharmaceutical preparations and aqueous samples.  相似文献   

7.
The paper presents a procedure for the multi-element inorganic speciation of As(III, V), Se(IV, VI) and Sb(III, V) in natural water with GF-AAS using solid phase extraction technology. Total As(III, V), Se(IV, VI) and Sb(III, V) were determined according to the following procedure: titanium dioxide (TiO2) was used to adsorb inorganic species of As, Se and Sb in sample solution; after filtration, the solid phase was prepared to be slurry for determination. For As(III), Se(IV) and Sb(III), their inorganic species were coprecipitated with Pb-PDC, dissolved in dilute nitric acid, and then determined. The concentrations of As(V), Se(VI) and Sb(V) can be calculated by the difference of the concentrations obtained by the above determinations. For the determination of As(III), Se(IV) and Sb(III), palladium was chosen as a modifier and pyrolysis temperature was 800 °C. Optimum conditions for the coprecipitation were listed for 100 ml of sample solution: pH 3.0, 15 min of stirring time, 40.0 μg l−1 Pb(NO3)2 and 150.0 μg l−1 APDC. The proposed method was applied to the determination of trace amounts of As(III, V), Se(IV, VI) and Sb(III, V) in river water and seawater.  相似文献   

8.
The possibility of applying antimony-film modified glassy carbon electrode in sequential-injection analysis (SIA) was investigated with the objective of determining Pb(II) and Cd(II) by anodic stripping voltammetry (ASV). The conditions of antimony-film deposition concerning composition of the plating/carrier solutions, concentrations of Sb(III) and hydrochloric acid, effects of different supporting electrolyte salts, and plating potential were optimized. It was found that the antimony-film deposition on glassy carbon substrate in a sample solution consisting of 750 μg L−1 Sb(III), 0.5 mol L−1 HCl at −1.5 V (vs. Ag/AgCl/3 mol L−1 KCl) yielded a modified electrode suitable for the determination of Pb(II) and Cd(II) at the μg L−1 level. The reproducibility of the analytical signals was characterized by a relative standard deviation lower than 2.8%, and the calculated values of detection limits were 1.2 μg L−1 for Pb(II) and 1.4 μg L−1 for Cd(II). The presence of KSCN in the sample solution offers the possibility of detecting ions with more negative oxidation potentials like Zn(II), Mn(II) or Cr(III). The developed SIA-ASV procedure was compared with the commonly used batch method, and its applicability was tested on a spiked tap water sample.  相似文献   

9.
Liang Y  Yuan D  Li Q  Lin Q 《Analytica chimica acta》2006,571(2):184-190
Solid-phase extraction technique had been applied to extract molybdophosphoric heteropoly acid (MoP) paired with cetyltrimethylammonium bromide (CTAB) from seawater matrix using C18 sorbent. Chemiluminescence emission could be generated via MoP reaction with alkaline luminol. Based on these, a novel on-line solid-phase extraction method coupled with flow injection (FI) analysis and luminol chemiluminescence detection had been established to determine ultratrace orthophosphate in seawater. The MoP-CTAB compound could be efficiently extracted on an in-line Sep-Pak C18 cartridge, and rapidly eluted by 0.3 mol l−1 sulphuric acid-ethanol solution. Then the compound was reduced by luminol to produce chemiluminescence light, which could be detected using a luminescence analyzer. Experimental parameters were optimized using a univariate experimental design. Using artificial seawater with salinity of 35 as a matrix, the standard curve with a linear range between 0.005 and 0.194 μmol l−1 had been obtained, and the recovery and the detection limit of the proposed method were found to be 92.5% and 0.002 μmol l−1, respectively. The relative standard deviation (R.S.D.), which was determined over eight hour, was 4.66% (n = 7) for the artificial seawater at a concentration of 0.097 μmol l−1 orthophosphate. Si of 200 μmol l−1 would not interfere with the detection of 0.012 μmol l−1 orthophosphate compound. Three typical seawater samples were analyzed using both the proposed method and the magnesium hydroxide-induced coprecipitation (MAGIC) method, and the results of the two methods showed no significant difference using the t test. Compared to the MAGIC method, the proposed method was more sensitive, time saving and easy for on-line analysis.  相似文献   

10.
In this work, the determination of total As in seawater by hydride generation atomic fluorescence spectrometry was studied. The influence of the chemical, flow and instrumental parameters were investigated and optimized. The pre-reduction of As(V) to As(III) was performed using KI plus ascorbic acid in 3.5 mol L− 1 HCl medium. No multiplicative interference was present and external aqueous calibration could be used. The limit of detection was 36 ng L− 1, while the repeatability was 2% (n = 10), at a 500 ng L− 1 concentration level. The sample throughput was 15 h− 1 if triplicate measurements were made. The accuracy was assessed by the analysis of a seawater certified reference material and excellent agreement between the obtained and certified values was verified. The procedure was used for the analysis of seawater offshore samples collected at the Brazilian coast and results ranging from 860 to 1200 ng L− 1 were found.  相似文献   

11.
A rapid, high sensitivity method has been developed for the determination of As(III), As(V), Sb(III) and Sb(V) in milk samples by using hydride generation atomic fluorescence spectrometry. The method is based on the leaching of As and Sb from milk through the sonication of samples with aqua regia followed by direct determination of the corresponding hydrides both before and after reduction with KI. It was confirmed by recovery experiments on spiked commercially available samples that neither the reduced nor the oxidized forms of the elements under study or mixtures of the two oxidation states were modified by the room temperature sample treatment with aqua regia. The methodologies developed provided 3σ limit of detection values of 8.1, 10.3, 5.4 and 7.7 ng l−1 for As(III), As(V), Sb(III) and Sb(V) in the diluted samples. Average relative standard deviation values of 5.7, 5.5, 8.2 and 4.7% were found for determination of As(III), As(V), Sb(III) and Sb(V) in commercially available samples of different composition and origin containing from 3.5 to 13.6 ng g−1 total As and from 4.9 to 11.8 ng g−1 total Sb, it being confirmed that As(V) and Sb(V) are the main species present in the samples analyzed (62±5 and 73±5%, respectively). The time required to determine As and Sb species in milk involves 10 min sonication and 30 min prereduction but these steps can be carried out for several sample simultaneously. Additionally the fluorescence measurement step involves less than 20 min for three replicates of all the four measurements required. So, in less than 2 h it is possible to determine the content of As(III), As(V), Sb(III) and Sb(V) in four samples.  相似文献   

12.
This paper describes a new procedure for the determination of Sb (III) and Sb (V) by differential pulse adsorptive stripping voltammetry (DPAdSV) using pyrogallol as a complexing agent. The selection of the experimental conditions was made using experimental design methodology. The detection limits obtained were 1.03 × 10−10 and 9.48 × 10−9 mol dm−3 for Sb (III) and Sb (V), respectively.In order to carry out the simultaneously determination of both antimony species a partial least squares regression (PLS) is employed to resolve the voltammetric signals from mixtures of Sb (III) and Sb (V) in the presence of pyrogallol. The relative error in absolute value is less than 0.5% when concentrations of several mixtures are calculated. Moreover, the solution is analyzed for any possible effects of foreign ions. The procedure is successfully applied to the speciation of antimony in pharmaceutical preparations and water samples.  相似文献   

13.
A novel disk electrochemical hydride generator has been developed for the determination of As and Sb. Compared with the traditional thin-layer cell, the disk cell combined the advantages of quick assembly and easy operation. This electrochemical system for hydride generation in neutral buffer solutions has been studied for analytical usefulness in coupling with atomic fluorescence spectrometry. It was found that the use of neutral phosphate buffer solution could markedly increase the fluorescence intensity of As(III) and Sb(III) and reduce the impact of cathode erosion on the stability of signal intensity. At the same time, the fluorescence intensity of As(V) and Sb(V) were almost suppressed totally. The detection limits (3σ) of 0.031 μg L−1 As(III) and 0.026 μg L−1 Sb(III) in aqueous solutions were obtained, respectively. The precisions (n = 11) for 20 μg L−1 As(III) and Sb(III) were 2.0% and 2.7%, respectively. The method was successfully applied for determination of different oxidation states of As and Sb in environmental samples.  相似文献   

14.
The extraction of In(III) from HCl, H2SO4, and HNO3 media using a 0.20 mol l−1 Cyanex 923 solution in toluene is investigated. In(III) is quantitatively extracted over a fairly wide range of HCl molarity while from H2SO4 and HNO3 media the extraction is quantitative at low acid concentration. The extracted metal ion has been recovered by stripping with 1.0 mol l−1 H2SO4. The stoichiometry of the In(III): Cyanex 923 complex is observed to be 1:2. The extraction of In(III) is insignificantly changed in diluents namely toluene, n-hexane, kerosene (160-200 °C), cyclohexane, and xylene having more or less the same dielectric constants, whereas, it decreases with increasing polarity of diluents such as cyclohexanone and chloroform. The extractant is stable towards prolonged acid contact and there is a negligible loss in its extraction efficiency even after recycling for 20 times. The extraction behavior of some commonly associated metal ions namely V(IV), Ti(IV), Al(III), Cr(III), Fe(III), Ga(III), Sb(III), Tl(III), Mn(II), Fe(II), Cu(II), Zn(II), Cd(II), Pb(II), and Tl(I) has also been investigated. Based on the partition data the conditions have been identified for attaining some binary separations of In(III). These conditions are extended for the recovery of pure indium from zinc blend, zinc plating mud, and galena. The recovery of the metal ions is around 95% with purity approximately 99%.  相似文献   

15.
An electrochemical preconcentration at a controlled potential on the electrode in a flow-through mode followed by graphite furnace atomic absorption spectrometric (GFAAS) detection is proposed for determination of trace amounts of palladium. After electrolysis the polarization of the electrodes was changed and deposited metal was dissolved electrochemically in the presence of an appropriate stripping reagent. Conditions for the electrodeposition, such as pH of the solutions, a deposition potential, dissolution potential and a composition of stripping solution were optimised. The graphite electrode (GE) and glassy carbon electrode (GCE) were tested for the palladium reduction process. The detection limit of 0.05 ng ml−1 Pd (1 pg) was obtained after palladium preconcentration on the GCE and dissolution with 0.2 mol l−1 thiourea in 0.1 mol l−1 HCl followed by GFAAS detection. The method was applied for the determination of palladium in spiked tap water and road dust samples.  相似文献   

16.
A simple and sensitive method has been developed for the direct determination of toxic species of antimony in mushroom samples by hydride generation atomic fluorescence spectrometry (HG AFS). The determination of Sb(III) and Sb(V) was based on the efficiency of hydride generation employing NaBH4, with and without a previous KI reduction, using proportional equations corresponding to the two different measurement conditions. The extraction efficiency of total antimony and the stability of Sb(III) and Sb(V) in different extraction media (nitric, sulfuric, hydrochloric, acetic acid, methanol and ethanol) were evaluated. Results demonstrated that, based on the extraction yield and the stability of extracts, 0.5 mol L− 1 H2SO4 proved to be the best extracting solution for the speciation analysis of antimony in mushroom samples. The limits of detection of the developed methodology were 0.6 and 1.1 ng g− 1 for Sb(III) and Sb(V), respectively. The relative standard derivation was 3.8% (14.7 ng g− 1) for Sb(V) and 5.1% (4.6 ng g− 1) for Sb(III). The recovery values obtained for Sb(III) and Sb(V) varied from 94 to 106% and from 98 to 105%, respectively. The method has been applied to determine Sb(III), Sb(V) and total Sb in five different mushroom samples; the Sb(III) content varied from 4.6 to 11.4 ng g− 1 and Sb(V) from 14.7 to 21.2 ng g− 1. The accuracy of the method was confirmed by the analysis of a certified reference material of tomato leaves.  相似文献   

17.
Li F  Pang YQ  Lin XQ  Cui H 《Talanta》2003,59(3):627-636
Two maximal potential-resolved flow injection-electrochemiluminescent (FI-ECL) peaks were observed for Ru(bpy)32+/TPrA system at 0.90 and 1.05 V, and for Ru(phen)32+/TPrA at 1.01 and 1.25 V (vs. Ag/AgCl) in pH 8.0 phosphate buffer solutions. Sensitive ECL inhibition effects were observed in the presence of noradrenaline and dopamine for both of these systems. Therefore, an FI-ECL inhibition method for determination of noradrenaline and dopamine has been developed. Under optimal conditions, linear responses between logarithm of ECL intensity changes and logarithm of sample concentration were found for noradrenaline in the linear range (LR) of 4×10−8-1×10−5 mol l−1 with theoretical detection limit (DL) of 2.5×10−8 mol l−1 for Ru(bpy)32+/TPrA system, and in LR of 2×10−8-2×10−5 mol l−1 with DL of 7.1×10−9 mol l−1 for Ru(phen)32+/TPrA system; and for dopamine in LR of 8×10−8-2×10−5 mol l−1 with DL of 5.2×10−8 mol l−1 for Ru(bpy)32+/TPrA system, in LR of 4×10−8-2×10−5 mol l−1 with DL of 1.5×10−8 mol l−1 for Ru(phen)32+/TPrA system. It was applied for determination of commercial pharmaceutical injection samples with satisfied results. The mechanism of the inhibition effects was proposed in the preliminary way.  相似文献   

18.
The use of selective pre-concentration and differential pulse anodic stripping voltammetry (DPASV) using a carbon paste electrode modified (CPEM) with spinel-type manganese oxide has been proposed for the determination of lithium ions content in natural waters. The new procedure is based on the effective pre-concentration of lithium ions on the electrode surface containing spinel-type Mn(IV) oxide with the reduction of Mn(IV) to Mn(III) and consequently the lithium ions intercalation (insertion) into the spinel structure. The best DPASV response was reached for an electrode composition of 25% (m/m) spinel-type MnO2 in the paste, 0.1 mol l−1 tris(hydroxymethyl)aminomethane (TRIS) buffer solution of pH 8.3, scan rate of 5 mV s−1, accumulation potential of 0.3 V versus saturated calomel reference electrode (SCE), pre-concentration time of 30 s and potential pulse amplitude of 50 mV. In these experimental conditions, the proposed methodology responds to lithium ions in the concentration range of 2.8×10−6 to 2.0×10−3 mol l−1 with a detection limit of 5.6×10−7 mol l−1. The determination of the lithium ions content in different samples of natural waters samples using the proposed methodology and atomic absorption spectrophotometry are in agreement at the 95% confidence level and within an acceptable range of error.  相似文献   

19.
Erdem A  Eroğlu AE 《Talanta》2005,68(1):86-92
A selective matrix removal/separation/enrichment method, utilizing a microcolumn of a chelating resin with SH functional groups (Duolite GT-73), was proposed for the determination of Sb(III) in waters by segmented flow injection-hydride generation atomic absorption spectrometry (SFI-HGAAS). The resin was selective to Sb(III) at almost all pH and acidity values employed, whereas Sb(V) was not retained at all and could be determined after a pre-reduction step with l-cysteine. Spike recoveries were tested at various concentration levels in different water types and were found to vary between 85 and 118%. Accuracy of the proposed methodology was checked by analyzing a standard reference material and a good correlation was found between the determined (13.3 ± 1.1 μg l−1) and the certified value (13.79 ± 0.42 μg l−1). The method was applied to several bottled drinking water samples for antimony determination with and without preconcentration and none of the samples were found to contain antimony above the permissible level (5 μg l−1). The characteristic concentration (the concentration of the analyte corresponding to an absorbance of 0.0044) was 0.55 μg l−1 and the 3 s limit of detection (LOD) based on five times preconcentration was 0.06 μg l−1. The applicability of the microcolumn separation/preconcentration/matrix removal method for flow injection systems was also demonstrated.  相似文献   

20.
A separation procedure for antimony(III) and antimony(V) was developed with the use of chelating celluloses. Sb(III) was separately pre-concentrated on imino diacetic acid–ethyl cellulose in the acidic pH range, in which the uptake of Sb(V) was negligible in the μg L− 1 concentration range. On the other hand, both Sb species Sb(V) and Sb(III) were pre-concentrated on a chloride form of 2,2′-diaminodiethylamine-cellulose. These solid phase extraction procedures were combined with graphite furnace atomic absorption spectrometry (SPE–GFAAS) for Sb detection. Pharmaceutical compounds of organic and inorganic types (ten compounds), as well as mineral water samples (twelve types) were analyzed. Detection limits of 0.18 µg L− 1 Sb(III) and 0.25 µg L− 1 Sb(V) were found in aqueous sample solutions and water samples, respectively, considering a 25-fold pre-concentration. The total Sb, mostly in the form of Sb(V), could be determined in phosphate-containing pharmaceuticals, while in phosphoric acid, Sb(III) was the dominant form. In all other types of samples the Sb content was below the detection threshold, and therefore, the potential suitability of the SPE–GFAAS method for the determination of Sb(III) species was proven by recovery tests of spiked samples. This method ensures the required detection power with regard to the allowable Sb limits established by international organizations.  相似文献   

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