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.     

Heat-treated Saccharomyces cerevisiae for antimony speciation and antimony(III) preconcentration in water samples

An analytical method was developed for antimony speciation and antimony(III) preconcentration in water samples. The method is based on the selective retention of Sb(III) by modified Saccharomyces cerevisiae in the presence of Sb(V). Heat, caustic and solvent pretreatments of the biomass were investigated to improve the kinetics and thermodynamics of Sb(III) uptake process at room temperature. Heating for 30 min at 80 degrees C was defined as the optimal treatment. Antimony accumulation by the cells was independent of pH (5-10) and ionic strength (0.01-0.1 mol L(-1)). 140 mg of yeast and 2h of contact were necessary to ensure quantitative sequestration of Sb(III) up to 750 microg L(-1). In these conditions, Sb(V) was not retained. Sb(V) was quantified in sorption supernatant by inductively coupled plasma mass spectrometry (ICP-MS) or inductively coupled plasma optical emission spectrometry (ICP-OES). Sb(III) was determined after elution with 40 mmol L(-1) thioglycolic acid at pH 10. A preconcentration factor close to nine was achieved for Sb(III) when 100mL of sample was processed. After preconcentration, the detection limits for Sb(III) and Sb(V) were 2 and 5 ng L(-1), respectively, using ICP-MS, 7 and 0.9 microg L(-1) using ICP-OES. The proposed method was successfully applied to the determination of Sb(III) and Sb(V) in spiked river and mineral water samples. The relative standard deviations (n=3) were in the 2-5% range at the tenth microg L(-1) level and less than 10% at the lowest Sb(III) and Sb(V) tested concentration (0.1 microg L(-1)). Corrected recoveries were in all cases close to 100%.     

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 using chromosorb 102 resin as a retention medium.

The selective retention of the Sb(III) chelate with ammonium pyrrolidine dithiocarbamate (APDC) on a column of Chromosorb 102 resin from a buffered sample solution including Sb(V) was used for the determination of Sb(III). The retained antimony was eluted with acetone. The retention of the Sb(III)-iodide compounds with sodium iodide on the Chromosorb 102 resin column from the same solution after reducing Sb(V) to Sb(III) by iodide in acidic solution was used to preconcentrate the total antimony. The retained antimony was eluted with 0.25 mol l(-1) HNO3. The antimony in the effluent was determined by flame atomic-absorption spectrometry. Also, the total antimony was determined directly by graphite-furnace atomic absorption spectrometry. The Sb(V) concentration could be calculated by the difference. The recoveries were > or = 95%. The detection limits of a combination of the column procedure and flame AAS for antimony were 6 - 61 microg l(-1) and comparable to 4 microg l(-1) for a direct GFAAS measurement. The relative standard deviations were <6%. The procedure was applied to the determination of Sb(III) and Sb(V) in spiked tap water, waste-water samples and a certified copper metal with the satisfactory results.     

Separation of antimony(III) with iodide and dithizone by sorption on polyurethane foam from sulphuric acid medium for its spectrophotometric determination in glasses

A method for quantitative separation of antimony(III) by sorption on polyether based polyurethane foam and its spectrophotometric determination has been described. The method involves formation of a pink-red complex of antimony(III) with iodide (0.045M) and dithizone (2.3 x 10(-5)M) in 0.25-0.75M H(2)SO(4) medium, sorption of the complex on polyurethane foam (within 45 min) at room temperature followed by its elution with acidified acetone (acetone containing 0.008% H(2)SO(4)) and spectrophotometric measurement at 507.2 nm ( = 2.56 x 10(4) l mol cm). The method obeys Beer's law from 0.1 to 6.0 mug antimony(III). Tolerance limits of other ions are Co (100 mug), Ni (100 mug), Fe (10 mug), Cu (0.5 mug), Sn (20 mug), Zn (100 mug), As (100 mug), Mn (200 mug), Pb (50 mug), Ti (100 mug), V (50 mug), etc. Interference by iron and copper have been eliminated by treating with KOH prior to the extraction of antimony. The method has been standardized with glass samples spiked with known amounts of antimony and applied to the determination of antimony in various glasses.     

Adsorptive stripping voltammetric determination of antimony

A new method is described for the determination of antimony based on the cathodic adsorptive stripping of Sb(III) complexed with 2′,3,4′,5,7-pentahydroxyflavone(morin) at a static mercury drop electrode (SMDE). The reduction current of the adsorbed antimony complex was measured by 1.5th-order derivative linear-sweep adsorption voltammetry. The peak potential is at −0.51 V (vs. SCE). The effects of various parameters on the response are discussed. The optimized analytical conditions were found to be: supporting electrolyte, chloroacetic acid (0.04 mol/l, pH 2.3); concentration of morin, 5×10⁻⁶ mol/l; accumulation potential, −0.25 V (vs. SCE); scan rate, 100 mV/s. The limit of detection and the linear range were 7×10⁻¹⁰ mol/l and 1.0×10⁻⁹3.0×10⁻⁷ mol/l Sb(III) for a 2-min accumulation time, respectively. This method has been applied to the determination of Sb(III) in steel and brass samples and satisfactory results were obtained. The adsorptive voltammetric characteristics and composition of the Sb(III)–morin complex were studied.     

Atomic fluorescence spectrometric determination of trace amounts of arsenic and antimony in drinking water by continuous hydride generation

A highly sensitive and simple method has been developed for the determination of As(III), total As, Sb(III) and total Sb in drinking water samples by continuous hydride generation and atomic fluorescence spectrometry (HGAFS). For As determination, water samples aspirated in a carrier of 2 mol l(-1) HCl were merged with a reducing NaBH(4) 3%(m/v) solution, with sample and NaBH(4) flow rates of 12.5 and 1.5 ml min(-1) respectively. The hydride generated in a 170 cm reaction coil was transported to the detector with an Ar flow of 400 ml min(-1), and a limit of detection between 5 and 20 ng l(-1) was obtained. For Sb determination, 2.5 mol l(-1) HCl and 2%(m/v) NaBH(4) were employed, with respective flow rates of 9.7 and 2 ml min(-1). The hydride generated in a 50 cm reaction coil was transported to the detector with an Ar flow rate of 300 ml min(-1), and a limit of detection between 6 and 14 ng l(-1) was obtained. Determination of the total concentration of these elements was obtained after a previous reduction with KI. Recovery studies of different added concentrations of these species in natural water samples were between 93 and 104% for As(III), 96-103% for As(V), 93-101% for Sb(III) and 90-119% for Sb(V).     

Stability studies of arsenic, selenium, antimony and tellurium species in water, urine, fish and soil extracts using HPLC/ICP-MS

The stability of arsenic, selenium, antimony and tellurium species in water and urine (NIST SRM 2670n) as well as in extracts of fish and soil certified reference materials (DORM-2 and NIST SRM 2710) has been investigated. Stability studies were carried out with As(III), As(V), arsenobetaine, monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), phenylarsonic acid (PAA), Se(IV), Se(VI), selenomethionine, Sb(III), Sb(V) and Te(VI). Speciation analysis was performed by on-line coupling of anion exchange high-performance liquid chromatography (HPLC) with inductively coupled plasma mass spectrometry (ICP-MS). Best storage of aqueous mixtures of the examined species was achieved at 3 degrees C whereas at -20 degrees C species transformation especially of selenomethionine and Sb(V) took place and a new selenium species appeared within a period of 30 days. Losses and species transformations during extraction processes were investigated. Extraction of the spiked fish material with methanol/water led to partial conversion of Sb(III), Sb(V) and selenomethionine to two new antimony and one new selenium species. The other arsenic, selenium and tellurium species were almost quantitatively extracted. For soil spiked with MMA, PAA, Se(IV) and Sb(III), recoveries after extraction with water and sulfuric acid (0.01 mol/L) were below 20%.     

A simple spectrophotometric procedure for the determination of antimony (III) and (V) in antileishmanial drugs

A spectrophotometric method for the selective determination of antimony (III) and (V) in antileishmanial drugs is described. The procedure is based on the reaction of Sb(III) with bromopyrogallol red (BPR) in neutral solution. As a consequence of the Sb-BPR complex formed, the absorbance of BPR, at 560 nm, decreases proportionally to the amount of Sb(III) in the analyte solution. The calculated apparent molar absorptivity and determination limits are 3.67 × 10⁴ L?·?cm^–1?·?mol^–1 and 1.65 × 10^–6 mol/L, respectively. Sb(V) is determined after reduction to Sb(III) by iodide. The Sb(V) content determined in ten samples of Glucantime varied from 75.40 ± 0.97 to 94.47 ± 1.0 mg/mL. Sb(III) was detected in all samples analyzed, and mean values ranged from 5.19 ± 0.16 to 10.52 ± 0.15 mg/mL. The method is suitable for the routine quality control of pharmaceutical formulations.     

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     

Speciation of antimony by preconcentration of Sb(III) and Sb(V) in water samples onto nanometer-size titanium dioxide and selective determination by flow injection-hydride generation-atomic absorption spectrometry.

A novel method for prevention of the oxidation of Sb(III) during sample pretreatment, preconcentration of Sb(III) and Sb(V) with nanometer size titanium dioxide (rutile) and speciation analysis of antimony, has been developed. Antimony(III) could be selectively determined by flow injection-hydride generation-atomic absorption spectrometry, coexisting with Sb(V). Trace Sb(III) and Sb(V) were all adsorbed onto 50 m g TiO2 from 500 ml solution at pH 3.0 within 15 min, then eluted by 10 ml of 5 mol/l HCl solution. One eluent was directly used for the analysis of Sb(III); to the other eluent was added 0.5 g KI and 0.2 g thiourea to reduce Sb(V) to Sb(III), then the mixture was used for the determination of total antimony. The antimony(V) content is the mathematical difference of the two concentrations. Detection limits (based on 3sigma of the blank determinations, n=11) of 0.05 ng/ml for Sb(III) and 0.06 ng/ml for Sb(V), were obtained.     

New considerations about the separation and quantification of antimony species by ion chromatography-hydride generation atomic fluorescence spectrometry

A new method for the speciation of inorganic [Sb(III) and Sb(V)] and organic (Me3SbCl2) antimony species by using a polystyrene-divinylbenzene-based anion-exchange HPLC column (Hamilton PRP-X100) coupled to hydride generation atomic fluorescence spectrometry (HG-AFS) is presented. Several mobile phases were tested for the baseline separation of these three antimony species, investigating in detail experimental parameters such as concentration and pH. The best efficiency and resolution was achieved by using a gradient elution between diammonium tartrate 250 mmol l(-1) pH 5.5 (A) and KOH 20 mmol l(-1) pH 12 (B). The gradient programme used was 100% B for 1.5 min, decreasing to 0% B in 0.1 min and maintained the elution with 100% A for 5.5 min. Analysis time was less than 7 min. Equilibration of the column with the complexing mobile phase was found to be critical in order to avoid Sb(III) double peak formation. Dilution in diammonium tartrate medium was necessary in order to avoid Sb(III) oxidation at microg l(-1) concentration level. Detection limits of 0.06 microg l(-1) for Sb(V), 0.09 microg l(-1) for Me3SbCl2 and 0.04 microg l(-1) for Sb(III) as well as repeatability and reproducibility better than 5% R.S.D. (n = 10) and 9% R.S.D. (n = 30) (for 1 and 5 microg l(-1) of Sb(V) and Sb(III) and 5 and 10 microg l(-1) of Me3SbCl2) were obtained. Accuracy and recovery studies were carried out by analysing one river freshwater sample and two water certified reference materials. The proposed methodology can be considered reliable and straightforward for antimony speciation in fresh water samples.     

Spectrophotometric determination of Sb(III) in Sb(III)/Sb(V) binary mixtures using sodium dodecylsulfate/nonylphenoxy polyethoxyethanol mixed micellar media

Different micellar media had different effects on the absorption spectra of the complexes of bromopyrogallol red with Sb(III) and Sb(V). The mixed micellar medium composed of 0.7 ml of 0.2% sodium dodecylsulfate (SDS) and 0.3 ml of 2% nonylphenoxypolyethoxyethanol (OP) at 80 degrees C could be used for the sensitive determination of Sb(III) in Sb(III)/Sb(V) binary mixtures. Under the optimal conditions, Beer's Law was obeyed over the range 0.1-2.3 mug ml(-1) Sb(III) with molar absorptivity at 538 nm being 4.8 x 10(4) l mol(-1) cm(-1) and detection limit 0.04 mug ml(-1). For 10 mug Sb(III), more than 100 mug Sb(V) could be tolerated (error < 3%) in the presence of SDS/OP micellar medium as compared with 0.1 mug Sb(V) in the absence of SDS/OP micellar medium. In addition, the sensitivity of Sb(III) in the micellar medium was much higher than that in pure water medium. As compared with conventional extraction spectrometry, the proposed method produced a reproducible result. It did not need the conversion of Sb(III) to Sb(V) and a time-consuming extraction process. A detailed discussion on the selection of surfactants, the effect of temperature, and the role played by the mixed surfactants were also made.     

Differential determination of antimony(III) and antimony(V) by solvent extraction-spectrophotometry with mandelic acid and Malachite Green, based on the difference in reaction rates

Highly sensitive and reproducible extraction-spectrophotometric methods for differential determination of antimony(III) and antimony(V) were investigated. It was found that antimony(III) reacts easily with mandelic acid to form a complex anion extractable into chlorobenzene with Malachite Green from weakly acidic media (pH 2.2-3.5) at room temperature, whereas antimony(V) reacts only slowly, and heating for 15 min at 45 degrees is needed to obtain maximum sensitivity. The significant difference between the rates of reaction of mandelic acid with antimony(III) and antimony(V) was applied to the differential determination of these two species. The calibration graph was linear over the range 0.15-6.0 mug for antimony(III), and 0.20-10 mug for antimony(V).     

A simple spectrophotometric procedure for the determination of antimony (III) and (V) in antileishmanial drugs

A spectrophotometric method for the selective determination of antimony (III) and (V) in antileishmanial drugs is described. The procedure is based on the reaction of Sb(III) with bromopyrogallol red (BPR) in neutral solution. As a consequence of the Sb-BPR complex formed, the absorbance of BPR, at 560 nm, decreases proportionally to the amount of Sb(III) in the analyte solution. The calculated apparent molar absorptivity and determination limits are 3.67 × 10⁴ L · cm^–1 · mol^–1 and 1.65 × 10^–6 mol/L, respectively. Sb(V) is determined after reduction to Sb(III) by iodide. The Sb(V) content determined in ten samples of Glucantime varied from 75.40 ± 0.97 to 94.47 ± 1.0 mg/mL. Sb(III) was detected in all samples analyzed, and mean values ranged from 5.19 ± 0.16 to 10.52 ± 0.15 mg/mL. The method is suitable for the routine quality control of pharmaceutical formulations. Received: 26 July 1996 / Revised: 17 October 1996 / Accepted: 11 December 1996     

Simultaneous determination of antimony(III) and antimony(V) by UV-vis spectroscopy and partial least squares method (PLS)

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.     

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 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 microg/L and 0.29 microg/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.     

Development of a non-chromatographic method for the speciation analysis of inorganic antimony in mushroom samples by hydride generation atomic fluorescence spectrometry

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.     

Solid phase chelating extraction and separation of inorganic antimony species in pharmaceutical and water samples for graphite furnace atomic absorption spectrometry

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.