Simultaneous determination of inorganic As(III), As(V), Sb(III), Sb(V), and Se(IV) species in natural waters by APDC/MIBK-NAA

A solvent extraction preconcentration as well as separation method involving ammonium pyrrolinedithiocarbamate (APDC) and 4-methyl-2-pentanone (MIBK) in conjunction with neutron activation analysis (NAA) was developed for the simultaneous measurement of low levels of inorganic arsenic, antimony and selenium species in natural waters. Several critical factors affecting the APDC/MIBK-NAA method were studied in detail including the selection of chelating agent, solvent, aqueous pH for the extraction of six species as well as a few organoarsenic species as representatives for organic species, the stability of the complexes in organic phase, phase volume ratios for extraction and back-extraction steps, and the reduction of the species from higher to lower oxidation state. The detection limits for arsenic, antimony and selenium were found to be as low as 0.026, 0.010 and 0.12 μg L^?1, respectively. Trace amounts of As(III), As(V), Sb(III), Sb(V), and Se(IV) in different types of natural water sample and two water certified reference materials were measured using the APDC/MIBK-NAA method.     

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 analysis of inorganic Sb(III) and Sb(V) ions by using mini column filled with Amberlite XAD-8 resin

The speciation of inorganic Sb(III) and Sb(V) ions in aqueous solution was studied. The adsorption behavior of Sb(III) and Sb(V) ions were investigated as iodo and ammonium pyrollidine dithiocarbamate (APDC) complexes on a column filled with Amberlite XAD-8 resin. Sb(III) and Sb(V) ions were recovered quantitatively and simultaneously from a solution containing 0.8 M NaI and 0.2 M H₂SO₄ by the XAD-8 column. Sb(III) ions were also adsorbed quantitatively as an APDC complex, but the recovery of the Sb(V)-APDC complex was found to be <10% at pH 5. According to these data, the concentrations of total antimony as Sb(III)+Sb(V) ions and Sb(III) ion were determined with XAD-8/NaI+H₂SO₄ and XAD-8/APDC systems, respectively. The Sb(V) ion concentration was calculated by subtracting the Sb(III) concentration found with XAD-8/APDC system from the total antimony concentration found with XAD-8/NaI+H₂SO₄ system. The developed method was applied to determine Sb(III) and Sb(V) ions in samples of artificial seawater and wastewater.     

Sb(III) and Sb(V) separation and analytical speciation by a continuous tandem on-line separation device in connection with inductively coupled plasma atomic emission spectrometry

A sensitive, precise and automated non-chromatographic method for Sb(III) and Sb(V) analytical speciation based on a continuous tandem on-line separation device in connection with inductively coupled plasma-atomic emission (ICP-AES) detection is proposed. Two on-line successive separation steps are included into this method: a continuous liquid-liquid extraction of Sb(III) with ammonium pyrrolidine dithiocarbamate (APDC) into methylisobuthylketone (MIBK), followed by direct stibine generation from the organic phase. Both separation steps are carried out in a continuous mode and on-line with the ICP-AES detector. Optimization of experimental conditions for the tandem separation and ICP-AES detection are investigated in detail. Detection limits for Sb(III) were 3 ng.mL(-1) and for Sb(V) 8 ng.mL(-1). Precisions observed are in the range +/- 5%. The proposed methodology has been applied to Sb(III) and Sb(V) speciation in sea-water samples.     

Selective separation and differential determination of antimony(III) and antimony(V) by solvent extraction with N-benzoyl-N-phenylhydroxylamine and graphite-furnace atomic-absorption spectrometry using a matrix-modification technique

If copper is used as a matrix modifier for the determination of antimony, the ashing temperature for antimony in aqueous solution and a BPHA-CHCl(3) extract can be raised to 1300 degrees and 1100 degrees , respectively. A selective procedure for separating antimony(III) from antimony(V) by extraction with BPHA in chloroform is described, along with the conditions for preserving trace antimony in water samples. The recommended method has been applied satisfactorily to the determination of antimony(III) and antimony(V) in various types of water at sub-ng/ml levels.     

Sb(III) and Sb(V) separation and analytical speciation by a continuous tandem on-line separation device in connection with inductively coupled plasma atomic emission spectrometry

A sensitive, precise and automated non-chromatographic method for Sb(III) and Sb(V) analytical speciation based on a continuous tandem on-line separation device in connection with inductively coupled plasma-atomic emission (ICP-AES) detection is proposed. Two on-line successive separation steps are included into this method: a continuous liquid-liquid extraction of Sb(III) with ammonium pyrrolidine dithiocarbamate (APDC) into methylisobuthylketone (MIBK), followed by direct stibine generation from the organic phase. Both separation steps are carried out in a continuous mode and on-line with the ICP-AES detector. Optimization of experimental conditions for the tandem separation and ICP-AES detection are investigated in detail. Detection limits for Sb(III) were 3 ng.mL^–1 and for Sb(V) 8 ng.mL^–1. Precisions observed are in the range ± 5%. The proposed methodology has been applied to Sb(III) and Sb(V) speciation in sea-water samples.     

Antimony speciation by inductively coupled plasma mass spectrometry using solid phase extraction cartridges

A novel and simple method for inorganic antimony speciation is described based on selective solid phase extraction (SPE) separation of antimony(III) and highly sensitive inductively coupled plasma mass spectrometric (ICP-MS) detection of total antimony and antimony(V) in the aqueous phase of the sample. Non-polar SPE cartridges, such as the Isolute silica-based octyl (C8) sorbent-containing cartridge, selectively retained the Sb(III) complex with ammonium pyrrolidine dithiocarbamate (APDC), while the uncomplexed Sb(V) remained as a free species in the solution and passed through the cartridge. The Sb(III) concentration was calculated as the difference between total antimony and Sb(V) concentrations. The detection limit was 1 ng L(-1) antimony. Factors affecting the separation and detection of antimony species were investigated. Acidification of samples led to partial or complete retention of Sb(V) on C8 cartridge. Foreign ions tending to complex with Sb(III) or APDC did not interfere with the retention behavior of the Sb(III)-APDC complex. This method has been successfully applied to antimony speciation of various types of water samples.     

Extraction behavior of Tm(III), Dy(III) and Sm(III) lanthanide with N-benzoyl-N-phenylhydroxalamine

The extraction of Sm(III), Dy(III) and Tm(III) with N-benzoyl-N-phenylhydroxalamine (BPHA) in benzene at pH range (1–10) has been studied. Quantitative separation was found in borate media at pH 8. The slope analysis showed that the extracted complex was M(BPHA)₃, where M=Sm(III), Dy(III) and Tm(III). The effect of various masking agents indicated that EDTA, oxalate, fluoride, phosphate and citrate, interfered in this study. Decontamination study showed that Cu(II), Zn(II), Ni(II), Co(II), Cr(III), Sc(III) and Fe(III) had very poor separation factors, whereas Sn(II), Cd(II), In(III), Ru(II), Hg(II), Ag(I), Ta(V) and Hf(IV) had very large separation factor. The effect of different diluents showed that carbontetrachloride, chloroform, benzene, toluene, nitrobenzene dichloromethane, MIBK and cyclohexanone were equally good for extraction except TBP due to ion association.     

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.     

Speciation of antimony(III) and antimony(V) in cell extracts by anion chromatography/ inductively coupled plasma mass spectrometry

An analytical method for the separation and quantification of Sb(III) and Sb(V) using anion chromatography with ICP-MS is presented. The optimum conditions for the separation of the antimony species were established with 15 mmol/L nitric acid at pH 6 as eluent system on a PRP-X100 column. The retention times for antimony(V) and antimony(III) were 85 s and 300 s with detection limits of 0.06 μg/L and 0.29 μg/L, respectively. The proposed method was applied to cell extracts of Leishmania donovani, which were incubated with antimony(III) and antimony(V). Some metabolism seemed to occur within the cells.     

121Sb-Mössbauer-Spektren von Antimon(V)-Verbindungen. III

¹²¹Sb Mössbauer Spectra of Antimony (V) Compounds. III The Mössbauer resonance effect of ¹²¹Sb has been studied in the antimony(V) compounds I–VI. Isomer shift and quadrupole splitting variations are considered in the light of results of vibrational spectroscopy and in part of X-ray data. The antimony iodine azides II and IV , respectively, were obtained by reactions of R₃Sb (R = CH₃, C₆H₅) with iodine azide.     

Some aspects of n-benzoylphenylhydroxylamine and cupferron reactions with tin,antimony and other selected elements

N-Benzoyl-N-phenylhydroxylamine (BPHA) and cupferron are compared in the liquid-liquid extraction of tin and antimony. As in their precipitation reactions tin(II) and tin(IV) behave similarly with BPHA and differently with cupferron. Both reagents behave similarly in extraction of antimony (III), except at high acidity when cupferron or its decomposition products prevent extraction which otherwise occurs into chloroform alone. Separations of Sn, Sb, As and Bi are discussed for extractions from hydrochloric and perchloric acid systems with BPHA. The tin product extracted with BPHA from dilute hydrochloric acid appears to be identical with that precipitated in gravimetric analysis; infrared spectral evidence shows the latter to contain tin(IV). Other precipitation reactions of BPHA in the presence of anions other than chloride and some solubility measurements are also reported.     

Speciation of antimony by differential generation of its volatile covalent hydride in aqueous and organic phase

By using the ammonium pyrrolidinedithiocarbamate (APDC) — methylisobutyl ketone (MIBK) extraction system Sb(III) is extracted into the organic phase. Sb(III) is directly determined in this organic phase by hydride generation AAS using NaBH₄/dimethylformamide solution as reducing agent. Sb(V) is determined in the aqueous phase using the same technique.     

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 microg 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 microg 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 microg 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.     

Using NAA to the Determination of Antimony in Trichlorosilane with Substoichiometric Extraction

Neutron activation analysis has been applied to the determination of trace of antimony based on the substoichiometric extraction of Sb(III) with BPHA (N-benzoyl-N-phenyl hydroxylamine). The antimony contens in trichlorosilane or high purity silicon can be determined by the proposed method down to ppb range. The effect of acid concentration, shaking time, the amount of carrier and the decontamination factors were studied.     

The solvent extraction of trace antimony(V)

An investigation of the extraction of trace amounts of antimony(V) from aqueous hydrochloric acid solutions into various others and chloroform has been carried out. Before extractions were made, mutual solubility studies of the two-phased systems were conducted. Then extraction experiments were performed using original aqueous acid concentrations from 0 to 12N and non-aqueous phases of ethyl ether, isopropye ether, isoamyl ether, n-hexyl ether, and chloroform. Dielectric constant determinations were made in the equilibrated non-aqueous phases, and spectrophotormetric and salting-out studies were carried out on the ethyl ether system. It was found that the isopropyl ether system presents the most advantageous conditions for the extraction of trace antimony(V)     

On-line determination of antimony(III) and antimony(V) in liver tissue and whole blood by flow injection - hydride generation - atomic absorption spectrometry

A new analytical procedure for the speciation of antimony in liver tissues is presented here. For this purpose, a flow injection system has been developed for the treatment of samples and the determination of antimony by hydride generation - atomic absorption spectrometry. The method involves the sequential and the on-line extraction of antimony(III) and antimony(V) from solid lyophilized blood and hamsters liver tissues, with 1.5 mol l(-1) acetic acid and 0.5 mol l(-1) sulfuric acid for Sb(III) and Sb(V), respectively. Reduction of Sb(V) to Sb(III) for stibine generation is effected by the on-line pre-reduction with l-cysteine. The linear ranges were 2.5-20 and 1.0-25 mug l(-1) of Sb(III) and Sb(V), respectively. The detection limits (3sigma) were 1.0 mug l(-1) for Sb(III) and 0.5 mug l(-1) for Sb(V). The relative standard deviation values for fifteen independent measurements were 2.1 and 1.8% for Sb(III) and Sb(V), respectively. The recovery studies performed with samples of cattle liver provided results from 98 to 100% for Sb(III) and from 100 to 103% for Sb(V) for samples spiked with single species. For samples spiked with both Sb(III) and Sb(V), the recovery varied from 97 to 103% for Sb(III) and from 101 to 103% for Sb(V).     

Determination of antimony(III) and total antimony by single-drop microextraction combined with electrothermal atomic absorption spectrometry

A simple and sensitive method for using electrothermal atomic absorption spectrometry (ET AAS) with Rh as permanent modifier determination of Sb(III) and total Sb after separation and preconcentration by N-benzoyl-N-phenylhydroxylamine (BPHA)-chloroform single drop has been developed. Parameters, such as pyrolysis and atomization temperature, solvent type, pH, BPHA concentration, extraction time, drop size, stirring rate and sample volume were investigated. Under the optimized experimental conditions, the detection limits (3σ) were 8.0 ng L⁻¹ for Sb(III) and 9.2 ng L⁻¹ for total Sb, respectively. The relative standard deviations (R.S.Ds.) were 6.6% for Sb(III) and 7.1% for total Sb (c = 0.2 ng mL⁻¹, n = 7), respectively. The enrichment factor was 96. The developed method has been applied successfully to the determination of Sb(III) and total Sb in natural water samples.     

Fractionation and redox speciation of antimony in agricultural soils by hydride generation--atomic fluorescence spectrometry and stability of Sb(III) and Sb(V) during extraction with different extractant solutions

This stability of Sb(III) and Sb(V) species was studied during single extraction from soils by water. EDTA, diluted H2SO4 and H3PO4, and oxalic acid/oxalate solutions, with and without ascorbic acid, were used as stabilizing reagent of both Sb species. Antimony redox speciation in soil extracts was performed by selective hydride generation-atomic fluorescence spectrometry. Simulated extraction procedures (without soil) showed that, except in oxalate medium, Sb(III) was oxidized to Sb(V), and this reaction was avoided with ascorbic acid. Recovery studies from a spiked agricultural soil showed that no oxidation but sorption of Sb(III) occurred during the extraction process in water and H2SO4 medium, and quantitative oxidation in EDTA and oxalate medium. With ascorbic acid, this oxidation was totally avoided in EDTA and partially avoided in oxalate solution. A new sequential extraction procedure was proposed and applied to the fractionation and redox speciation of antimony in agricultural soils, using EDTA + ascorbic acid, pH 7 (available under complexing and moderately reducible conditions); oxalic acid/oxalate + ascorbic acid (extractable in reducible conditions) and HNO3 + HCl + HF (residual fraction). The proposed extraction scheme can provide information about the availability and mobility of antimony redox species in agricultural soils.     

Bioaccumulation of Antimony by Chlorella vulgaris and the Association Mode of Antimony in the Cell

The bioaccumulation and excretion of antimony by the freshwater alga Chlorella vulgaris , which had been isolated from an arsenic-polluted environment, are described. When this alga was cultured in a medium containing 50 μg cm⁻³ of antimony(III) for 14 days, it was found that Chlorella vulgaris bioaccumulated antimony at concentrations up to 12 000 μg Sb g⁻¹ dry wt after six days' incubation. The antimony concentration in Chlorella vulgaris decreased from 2570 to 1610 μg Sb g⁻¹ dry wt after the cells were transferred to an antimony-free medium. We found that the excreted antimony consists of 40% antimony(V) and 60% antimony(III). This means that the highly toxic antimony(III) was converted to the less toxic antimony (V) by the living organism. Antimony accumulated in living Chlorella vulgaris cells was solvent-fractionated with chloroform/methanol (2:1), and the extract residue was fractionated with 1% sodium dodecyl sulfate (SDS). Gel-filtration chromatography of the solubilized part showed that antimony was combined with proteins whose molecular weight was around 4×10⁴ in the antimony-accumulated living cells. © 1997 by John Wiley & Sons, Ltd.