Determination of total antimony(III,V) by square-wave anodic stripping voltammetry with in situ plated bismuth-film electrode

A sensitive and reliable method is described for the determination of total Sb(III,?V) at traces levels by Osteryoung square-wave anodic stripping voltammery (OSWASV). This method is based on the co-deposition of Sb(III,?V) with Bi(III) onto an edge-plane pyrolytic graphite substrate at an accumulation step. OSWASV studies indicated that the co-deposited antimony was oxidised with anodic scans to give an enhanced anodic peak at about 450?mV vs. Ag/AgCl (sat. KCl). The anodic stripping peak current was directly proportional to the total concentration of antimony in the ranges of 0.01–0.10?µg?L^?1, 0.10–1.0?µg?L^?1 and 1.0–18.0?µg?L^?1 with correlation coefficient higher than 0.995 when 2.0?mol?L^?1 hydrochloric acid was used. The detection limits calculated as S/N?=?3 was 5.0?ng?L^?1 in 2.0?mol?L^?1 hydrochloric acid at 180?s deposition time. The relative standard deviation was 5% (n?=?6) at 0.10?µg?L^?1 level of antimony. The analytical results demonstrate that the proposed method is applicable to analyses of real water samples.     

Speciation of volatile antimony compounds in culture headspace gases of Cryptococcus humicolus using solid phase microextraction and gas chromatography–mass spectrometry

Direct analysis of the volatile antimony compounds stibine (SbH₃), monomethylantimony, dimethylantimony (Me₂Sb) and trimethylantimony (Me₃Sb) using solid phase microextraction (SPME) with polydimethylsiloxane fibres and gas chromatography–mass spectrometry (GC–MS) is described. The best analyte to background signal ratio was achieved using a 20 min extraction time. Antimony species were separated using a 3% phenylmethylsilicone capillary column operated at a column pressure of 70 kPa, a flow rate of 1.4 ml min^?1 and temperature ramping from 30 to 36 °C at 0.1 °C min^?1. Cryogenic focusing of desorbed species was required to achieve resolution of antimony species. The optimized SPME–GC–MS method was applied to the analysis of headspace gases from cultures of Cryptococcus humicolus incubated with inorganic antimony(III) and (V) substrates. The headspace gases from biphasic (aerobic–anaerobic) biomass‐concentrated culture incubations revealed the presence of SbH₃, Me₂Sb and Me₃Sb. Stibine was the major antimony species detected in cultures amended with inorganic antimony(V). Me₃Sb was the sole volatile antimony species detected when cultures were amended with antimony(III). Copyright © 2002 John Wiley & Sons, Ltd.     

Microcolumn sorption of antimony(III) chelate for antimony speciation studies

Selective sorption of the Sb(III) chelate with ammonium pyrrolidine dithiocarbamate (APDC) on a microcolumn packed with C₁₆-bonded silica gel phase was used for the determination of Sb(III) and of total inorganic antimony after reducing Sb(V) to Sb(III) by l-cysteine. A flow injection system composed of a microcolumn connected to the tip of the autosampler was used for preconcentration. The sorbed antimony was directly eluted with ethanol into the graphite furnace and determined by AAS. The detection limit for antimony was significantly lowered to 0.007 μg l⁻¹ in comparison to 1.7 μg l⁻¹ for direct injection GFAAS. This procedure was applied for speciation determinations of inorganic antimony in tap water, snow and urine samples. For the investigation of long-term stability of antimony species a flow injection hydride generation atomic absorption spectrometry with quartz tube atomization (FI HG QT AAS) and GFAAS were used for selective determination of Sb(III) in the presence of Sb(V) and total content of antimony, respectively. Investigations on the stability of antimony in several natural samples spiked with Sb(III) and Sb(V) indicated instability of Sb(III) in tap water and satisfactory stability of inorganic Sb species in the presence of urine matrix.     

Chemical Speciation of Antimony(III and V) in Water by Adsorptive Cathodic Stripping Voltammetry Using the 4‐(2‐Thiazolylazo) – Resorcinol

A simple adsorptive cathodic stripping voltammetry method has been developed for antimony (III and V) speciation using 4‐(2‐thiazolylazo) – resorcinol (TAR). The methodology involves controlled preconcentration at pH 5, during which antimony(III) – TAR complex is adsorbed onto a hanging mercury drop electrode followed by measuring the cathodic peak current (I_p,c) at ?0.39 V versus Ag/AgCl electrode. The plot of I_p,c versus antimony(III) concentration was linear in the range 1.35×10^?9–9.53×10^?8 mol L^?1.The LOD and LOQ for Sb(III) were found 4.06×10^?10 and 1.35×10^?9 mol L^?1, respectively. Antimony(V) species after reduction to antimony(III) with Na₂SO₃ were also determined. Analysis of antimony in environment water samples was applied satisfactorily.     

Determination of major antimony species in seawater by continuous flow injection hydride generation atomic absorption spectrometry

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.     

Determination of Sb(III) and Total Sb in Antileishmanial Drugs by Spectrophotometric Flow‐Injection Hydride Generation

Abstract

A spectrophotometric procedure based on hydride generation and flow analysis is proposed for determination of antimony (III) [Sb(III)] and total antimony (Sb) in pharmaceutical samples. Firstly, Sb(III) reacts with hydrogen species generated in the system, forming antimony hydride. The reaction leads to a decrease in the permanganate concentration and, hence, in the intensity of the color of this specie, which is spectrophotometrically measured at 528 nm. Total Sb is determined as Sb(III) after Sb(V) reduction using 0.02% (m/v) KI. Some parameters, such as the number of channels of the gas phase separator, injection volume, coil length, and KBH₄ concentration, are investigated. The system presents a frequency of ca. 100 h^?1 and precision <3.0% [expressed as relative standard deviation (RSD) of 30 measurements using a 3.0 mg L^?1 Sb(III) solution]. The analytical curve ranging from 0.5 mg L^?1 to 5.0 mg L^?1 (r>0.998; n=5) permits limit of detection (LOD) and limit of quantification (LOQ) of 83 and 250 µg L^?1. For total Sb, the accuracy is checked by atomic absorption spectrometry applying the t test and the results are in accordance at the 95% confidence level. Recovery tests are used to check the accuracy for Sb(III) determination, and the recoveries are between 95% and 105%.     

Liquid chromatography-hydride generation-atomic fluorescence spectrometry hybridation for antimony speciation in environmental samples

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.     

Determination of antimony(III) and (V) in natural water by cathodic stripping voltammetry with in-situ plated bismuth film electrode

A method is described for the sequential determination of Sb(III) and Sb(V) using Osteryoung square wave cathodic stripping voltammetry. It employs an in-situ plated bismuth-film on an edge-plane graphite substrate as the working electrode. Selective electro-deposition of Sb(III)/Sb(V) is accomplished by applying a potential of ?500 mV vs. Ag/AgCl, followed by reduction to stibine at a more negative potential in the stripping step. Stripping was carried out by applying a square wave waveform between ?500 and ?1400 mV to the antimony deposited. The stripping peak current at ?1150 mV is directly proportional to the concentration of Sb( III)/Sb(V). The calibration plots for Sb (III) were linear up to 12.0?µg L^?1 depending on the time of deposition. The calibration plots for Sb (V) were linear up to 7.0?µg L^?1, also depending on the time of deposition. The relative standard deviation in the determination of 0.1?µg L^?1 of Sb(III) is 4.0% (n?=?5), and the limit of detection is as low as 2 ng L^?1. In case of 0.1?µg L^?1 Sb(V), the relative standard deviation is 3.0% (n?=?5) and the detection limit also is 2 ng L^?1. The method was applied to the analysis of river and sea water samples.     

Synthesis and Characterization of Antimony(III) Complexes of Thioamides,and Crystal Structure of {[Sb(Imt)2Cl2]2((2‐Imt)}Cl2(Imt=Imidazolidine‐2‐thione)

Antimony(III) complexes of thioamides [thioamides=thiourea (Tu), N,N′‐dimethylthiourea (Dmtu), tetramethylthiourea (Tmtu), imidazolidine‐2‐thione (Imt) and diazinane‐2‐thione (Diaz)] with the general formulae, Sb(thione)_nCl₃ (n=1, 2, 2.5, 3) were prepared and characterized by elemental analysis, IR and NMR (¹H, ¹³C) spectroscopic methods. The spectral data of the complexes are consistent with the coordination of the thiones to antimony(III). The crystal structure of one of them, {[Sb(Imt)₂Cl₂]₂(μ₂‐Imt)}Cl₂ ( 1 ), was determined by X‐ray crystallography, which shows that the complex is dinuclear consisting of two [Sb(Imt)₂Cl₂] units bridged by an Imt molecule. In 1 , the antimony atom is bonded to two chlorine atoms, two sulfur atoms of coordinated Imt molecules and one sulfur atom of a bridging Imt molecule. The antimony environment can be considered to be distorted octahedral with one Cl^? ion weakly bound to antimony.     

Ion chromatography–hydride generation‐atomic fluorescence spectrometry speciation of tellurium

The speciation of tellurium was carried out using atomic fluorescence spectrometry as an element‐specific detector in hybridization with liquid chromatography and hydride generation. Good resolution could be obtained by anion‐exchange chromatography with complexing agents, using a mobile phase with 8 mM EDTA and 2 mM potassium hydrogenphthalate. Analysis time was less than 6 min. Calibration graphs were linear between 2 and 100 µg l^?1. Detection limits were 0.6 µg l^?1 and 0.7 µg l^?1 for tellurium(VI) and tellurium(IV) respectively. The method was applied to the speciation of tellurium in drinking water and wastewater samples from different metallurgical industries. Copyright © 2005 John Wiley & Sons, Ltd.     

Determination of trace concentrations of antimony by the introduction of stibine into an inductively-coupled plasma for atomic emission spectrometry

A simple, rapid and sensitive method is described for the determination of trace concentrations of antimony by inductively-coupled plasma atomic emission spectrometry with hydride generation. Hydrochloric acid (1 M) is the best medium for stibine generation, but antimony(III) is also effectively reduced to stibine in 1 M malic acid or 0.5 M tartaric acid, whereas antimony(V) gives no significant signal in either of these acids. This permits the differential determination of Sb(III) and Sb(V). Most of the inter-element interference effects can be minimized by thiourea, bur standard additions are recommended for accurate determinations. Thiourea is also effective in prereducing Sb(V) to Sb(III). The detection limit is 0.19 ng Sb ml^?1 and the calibration graph is linear up to 100 μg ml^?1. The r.s.d, at 1 and 100 ng Sb ml^?1 are 3.8 and 2.1%, respectively. The method is applied to copper metal and to speciation of antimony in waste water.     

Inversvoltammetrische spurenbestimmung von Antimon(III) und Antimon(V) in aquatischen umweltproben nach selektiver extraktionStripping Voltammetry of Traces of Antimony(III) and Antimony(V) in Natural Waters After Selective Extraction

The biological activity of antimony depends on the oxidation state. The Sb(III) and Sb(V) states can be distinguished, even in the ng l^?1 range, by coupling extraction with ammonium pyrrlidenedithiocarbamate into methyl isobutyl ketone (APDC/MIBK), or N-benzoyl-N-phenylhydroxylamine (BPHA) into chloroform, with anodic stripping voltammetry (a.s.v.). After complex formation with APDC in acetate-buffered medium, Sb(III), but not Sb(V), is extracted into MIBK and quantified by a.s.v. Antimony(V) is quantified in the aqueous phase after removal of Sb(III) by extraction with BPHA into chloroform from the medium acidified with nitric acid. The applicability of the proposed separation/a.s.v. method is demonstrated for samples of rain, snow and water from a dredging operation. The stability of the two antimony species is examined for natural waters with Sb(III) and Sb(V) added; possibilities of stabilization are described. The precedures should be suitable for speciation of antimony in relatively unpolluted waters.     

Speciation of Organotin Compounds by Capillary Electrophoresis Coupled with Hydride Generation Atomic Fluorescence Spectrometry

Abstract

Capillary electrophoresis (CE) coupled with hydride generation atomic fluorescence spectrometry (HG‐AFS) was developed for the speciation analysis of organotin compounds. The four organotin cations of trimethyltin (TMT), monobutyltin (MBT), dibutyltin (DBT), and tributyltin (TBT) were completely separated by CE in a 50 cm×75 µm i.d. fused‐silica capillary at 15 kV and using a mixture of 50 mmol l^?1 H₃BO₃?50 mmol l^?1 Tris‐5% v/v methanol (pH 7.10) as electrolyte. 0.008 mmol l^?1 cetyltrimethylammonium bromide (CTAB) added to the electrolyte suppressed the adsorption of the organotin cations on the inner wall of capillary. The generated hydride species were detected on‐line with AFS. The precisions (RSD, n=5) were in the range of 1.7–3.1% for migration time and 3.8–4.7% for peak area response for the four organotin species. The detection limits ranged from 1–10 µmol l^?1 (as Sn).     

Adsorptive Stripping Voltammetric Determination of Antimony by Using Alizarin Red S

Abstract

A sensitive and selective voltammetric method for determination of antimony(III) using Alizarin Red S (ARS) as complexing agent is described. The method is based on the monitoring the oxidation peak of antimony(III)-ARS complex at ?520 mV in ammonium-ammonia buffer (pH = 7.5). The peak current was measured by scanning the potential from ?700 mV versus Ag/AgClto more positive potentials without accumulation in the presence of 1 × 10^?6 mol L^?1 of ARS. The limit of detection (3 s) and limit of quantification (10 s) of the method were calculated from calibration curve as 1.45 µg L^? and 4.8 µg L^? respectively. The calibration plot for antimony(III) was linear in the range of 4.8–30 µg L^?. The interference of various ions was examined. Serious interference from Al(III), Fe(III), Cu(II), Pb(II), and Zn(II) was eliminated by addition of EDTA to the solution. The method was applied to drinking water samples. The recoveries were in the range 94% – 105%. The results obtained from the developed method were compared with those from the differential-pulse anodic-stripping method and no statistically significant difference was found.     

Selective determination of antimony(III) and antimony(V) in liver tissue by microwave-assisted mineralization and hydride generation atomic absorption spectrometry

Antimony(III) and antimony(V) species have been selectively determined in liver tissues by optimizing the acidic conditions for the evolution of stibine using the reduction with sodium borohydride. The results show that a response for Sb(III) of 0.5 to 20 g l^–1 was selectively obtained from samples in a 1 mol l_–1 acetic acid medium. The best response for total antimony from 1 to 20 g l^–1 is obtained after sample treatment with a 0.5 mol l^–1 sulfuric acid and 10% w/v potassium iodide. Microwave digestion has been necessary to release quantitatively antimony species from sample slurries. The amount of Sb(V) was calculated from the difference between the value for total antimony and Sb(III) concentrations. A relative standard deviation from 2.9 to 3.1% and a detection limit of 0.15 and 0.10 g l^–1 for Sb(III) and total Sb has been obtained. The average accuracy exceeded 95% in all cases comparing the results obtained from recovery studies, electrothermal atomic absorption spectrometry and the analysis of certified reference materials.Dedicated to Professor Dr. Peter Brätter on the occasion of his 60th birthday     

Determination of Antimony(III) and Total Antimony in Aqueous Samples by Electrothermal Atomic Absorption Spectrometry After Dispersive Liquid–Liquid Microextraction (DLLME)

Dispersive liquid–liquid microextraction (DLLME) technique combined with electrothermal atomic absorption spectrometry (ET-AAS) was proposed for determination of antimony(III) and total antimony at very low concentrations in water samples. The N-benzoyl-N-phenylhydroxylamine (BPHA) was used as a chelating agent, and chloroform and ethanol were used as extraction and disperser solvents, respectively. The effect of various experimental parameters on the extraction and determination was investigated. The detection limits (3σ) were 0.005 μg L^?1 for Sb(III) and 0.008 μg L^?1 for total Sb. The developed method was applied successfully to the determination of Sb(III) and total Sb in natural water samples.     

Speciation Analysis of Antimony (III) and Antimony (V) by Flame Atomic Absorption Spectrometry After Separation/Preconcentration With Cloud Point Extraction

A sensitive and simple method for flame atomic absorption spectrometry (FAAS) determination of antimony species after separation/preconcentration by cloud point extraction (CPE) has been developed. When the system temperature is higher than the cloud point extraction temperature, the complex of antimony (III) with N-benzoyl-N-phenyhydroxylamine (BPHA) can enter the surfactant-rich phase, whereas the antimony (V) remains in the aqueous phase. Antimony (III) in surfactant-rich phase was analyzed by FAAS and antimony (V) was calculated by subtracting of antimony (III) from the total antimony after reducing antimony (V) to antimony (III) by L-cysteine. The main factors affecting the cloud point extraction, such as pH, concentration of BPHA and Triton X-114, equilibration temperature and time, were investigated systematically. Under optimized conditions, the detection limits (3σ) were 1.82 ng mL⁻¹ for Sb(III) and 2.08 ng mL⁻¹ for Sb(total), and the relative standard deviations (RSDs) were 2.6% for Sb(III) and 2.2% for Sb(total). The proposed method was applied to the speciation of antimony species in artificial seawater and wastewater, and recoveries in the range of 95.3–106% were obtained by spiking real samples. This technique was validated by means of reference water materials and gave good agreement with certified values.     

Speciation of Antimony by Adsorptive Stripping Voltammetry Using Pyrogallol Red

This paper proposes a procedure for the speciation of antimony by Differential Pulse Adsorptive Stripping Voltammetry (DPAdSV) using pyrogallol red (PGR) as a complexing agent. It employs a Partial Least Squares regression (PLS) in the resolution of strongly overlapping voltammetric signals obtained from mixtures of Sb(III) and Sb(V) in the presence of pyrogallol red. The absolute value of the relative error was less than 3.5% when concentrations of several mixtures were calculated, the minimum concentrations being 9.98×10^?9 mol dm^?3 and 4.87×10^?8 mol dm^?3 for Sb(III) and Sb(V), respectively. Any undue effects caused by the presence of foreign ions in the solution were also analyzed. The procedure was successfully applied to the speciation of antimony in pharmaceutical preparations.     

Determination of Antimony(III) by Differential Pulse Voltammetry Using a Gold Nanoparticle–Ionic Liquid–Graphene-Modified Selenium-Doped Carbon Paste Electrode

A simple and sensitive differential pulse stripping voltammetric method was developed for the determination of antimony(III) using a selenium-doped carbon paste electrode modified with an ionic liquid, graphene, and gold nanoparticles. The conditions, including the mass of graphene, concentration of hydrochloric acid, deposition potential, and deposition time were optimized by single-factor experiments. Under the optimal conditions, a linear equation of I_Sb(III) (µA)?=??16.9882???11.0929 c (µmol/L) (R?=?0.9965) and a detection limit of 2.7?×?10^?8?mol/L were obtained for 8.0?×?10^?8 to 4.8?×?10^?6?mol/L antimony(III). The response shows that the sensor enhances the sensitivity of antimony due to the high conductivity and large surface areas of the ionic liquid, graphene, and gold nanoparticles. This electrode may provide a new sensing platform for the determination of antimony.     

Simultaneous Determination of Antimony(III) and Molybdenum(VI) by Adsorptive Stripping Voltammetry Using Quercetin as Complexing Agent

A sensitive and selective voltammetric method for simultaneous determination of Sb(III) and Mo(VI) using Quercetin (Q) as complexing agent is described. Optimal conditions were found to be: pH 3.7, C_Q=6.0 µmol L^?1 and E_acc=?0.10 V. The LOD (3σ) for Sb(III) are 0.076 and 0.040 µg L^?1, whereas for Mo(VI) are 0.086 and 0.048 µg L^?1 with t_acc of 60 and 120 s, respectively. The method was validated using synthetic sea water (ASTM D665) and was applied to the determination of Sb(III) and Mo(VI) in natural waters with satisfactory results.