Determination Of Total Antimony Research Articles

Accurate Determination of Total Antimony Using ICP-MS and Optimization Its Extraction Efficiency From Reference and Soil Samples

Two independent digestion techniques (microwave acid digestion with HF and HCl, HNO3 and Na2O2 sintering, respectively) were applied to determine the total Sb concentration in a real soil sample and in reference materials: Icelandic Basalt (BIR-1), Cody Shale (SCo-1) and (Soil-7). ICP-MS was used to determine total antimony concentrations in the digested and the extracted solutions using external calibration and isotope dilution technique. The recoveries of Sb using HF in the acids digestion mixture in closed-vessels microwave digestion system were excellent and the concentrations are in very good agreement with certified or reported concentrations of reference materials. Using closed-vessels combined with microwave heating systems probably prevents the loss of volatile Sb compounds. The use of hydrogen fluoride with other strong acid can help dissociating insoluble antimony silicates. Different extraction reagents were tested for their ability to extract antimony using an ultrasonic bath namely: EDTA disodium salt, potassium hydroxide, citric acid monohydrate, pyridine-2,6-dicarboxylic acid, ammonium acetate, ammonium oxalate, ammonium thiocyanate, ammonium persulphate and di-ammonium hydrogen citrate. A 500 mmol L-1 solution of citric acid pH 1.08 proved to be the most efficient extractant. Optimization of the extraction conditions were investigated by studying the effect of pH, concentration, temperature, time of extraction, the ratio of sample mass to the volume of extractant and the number of consecutive extractions. As a result three consecutive extractions for a total time of 45 min at 80 ˚C was the most efficient condition for Sb extraction. Using these extraction conditions 61%, 3.7% RSD and 42%, 2.2% RSD (n=6) of the total antimony in the real soil and Soil-7 samples, respectively could be extracted.

Accurate Determination of Total Antimony Using ICP-MS and Optimization Its Extraction Efficiency From Reference and Soil Samples

Two independent digestion techniques (microwave acid digestion with HF and HCl, HNO3 and Na2O2 sintering, respectively) were applied to determine the total Sb concentration in a real soil sample and in reference materials: Icelandic Basalt (BIR-1), Cody Shale (SCo-1) and (Soil-7). ICP-MS was used to determine total antimony concentrations in the digested and the extracted solutions using external calibration and isotope dilution technique. The recoveries of Sb using HF in the acids digestion mixture in closed-vessels microwave digestion system were excellent and the concentrations are in very good agreement with certified or reported concentrations of reference materials. Using closed-vessels combined with microwave heating systems probably prevents the loss of volatile Sb compounds. The use of hydrogen fluoride with other strong acid can help dissociating insoluble antimony silicates. Different extraction reagents were tested for their ability to extract antimony using an ultrasonic bath namely: EDTA disodium salt, potassium hydroxide, citric acid monohydrate, pyridine-2,6-dicarboxylic acid, ammonium acetate, ammonium oxalate, ammonium thiocyanate, ammonium persulphate and di-ammonium hydrogen citrate. A 500 mmol L-1 solution of citric acid pH 1.08 proved to be the most efficient extractant. Optimization of the extraction conditions were investigated by studying the effect of pH, concentration, temperature, time of extraction, the ratio of sample mass to the volume of extractant and the number of consecutive extractions. As a result three consecutive extractions for a total time of 45 min at 80 ˚C was the most efficient condition for Sb extraction. Using these extraction conditions 61%, 3.7% RSD and 42%, 2.2% RSD (n=6) of the total antimony in the real soil and Soil-7 samples, respectively could be extracted.

On line automated system for the determination of Sb(V), Sb(III), thrimethyl antimony(v) and total antimony in soil employing multisyringe flow injection analysis coupled to HG-AFS

This paper proposes the use of a multisyringe flow injection analysis (MSFIA) system for inorganic antimony speciation analysis, trimethyl antimony(V) and determination of total antimony in soil samples using hydride generation atomic fluorescence spectrometry (HG-AFS). Total antimony has been determined after reduction of antimony(V) to antimony(III) using potassium iodide and ascorbic acid. For determination of total inorganic antimony the sample is percolated in a mini-column containing the Dowex 50W-X8 resin for retention of the organic species of antimony. Antimony(III) is quantified in presence of 8-hydroxyquinoline as masking agent for antimony(V) after an extraction step of the organic antimony species using the also same mini-column. The trimethyl antimony(V) content is found by difference between total antimony and total inorganic antimony. By other hand, antimony(V) is quantified by difference between total inorganic antimony and antimony(III). The analytical determinations were performed using sodium tetrahydroborate as reducing agent. The optimization step was performed using two-level full factorial design and Doehlert matrix involving the factors: hydrochloric acid and sodium tetrahydroborate concentrations and sample flow rate. The optimized experimental conditions allow the antimony determination utilizing the external calibration technique with limits of detection and quantification of 0.9 and 3.1ngg−1, respectively, and a precision expressed as relative standard deviation of 3.2% for an antimony solution of 5.0µgL−1. The method accuracy was confirmed by analysis of the soil certified reference material furnished from Sigma-Aldrich RTC. Additionally, addition/recovery tests were performed employing synthetic solutions prepared using trimethyl antimony(V), antimony(III), antimony(V) and five soil samples. The antimony extraction step was performed in a closed system using hydrochloric acid, ultrasonic radiation and controlled temperature. The method proposed was applied for analysis of thirteen soil samples collected in different sites of the Balearic Islands, Spain, and the results obtained varied from 19 to 46ngg−1 for trimethyl antimony(V) and from 113 to 215ngg−1 for total inorganic antimony. The concentrations obtained to antimony(V) were always higher than for antimony(III) in all the analyzed samples.

Multivariate optimization of a method for antimony determination by hydride generation atomic fluorescence spectrometry in hair samples of patients undergoing chemotherapy against Leishmaniasis.

A method was developed for determination of total antimony in hair samples from patients undergoing chemotherapy against Leishmaniasis based on the administration of pentavalent antimonial drugs. The method is based on microwave assisted digestion of the samples in a pressurized system, reduction of Sb5+ to Sb3+ with KI solution (10% w/v) in ascorbic acid (2%, w/v) and its subsequent determination by hydride generation atomic fluorescence spectrometry (HG-AFS). The proportions of each component (HCl, HNO3 and water) used in the digestion were studied applying a constrained mixtures design. The optimal proportions found were 50% water, 25% HNO3 and 25% HCl. Variables involved in the generation of antimony hydride were optimized using a Doehlert design revealing that good sensitivity is found when using 2.0% w/v NaBH4 and 4.4 mol L-1 HCl. Under the optimum experimental conditions, the method allows the determination of antimony in hair samples with detection and quantification limits of 1.4 and 4.6 ng g-1, respectively, and precision expressed as relative standard deviation (RSD) of 2.8% (n = 10 to 10.0 mg L-1). The developed method was applied in the analysis of hair samples from patients who take medication against Leishmaniasis.

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.

Determination of total antimony and inorganic antimony species by hydride generation in situ trapping flame atomic absorption spectrometry: a new way to (ultra)trace speciation analysis

The analytical performance of non-chromatographic coupled hydride generation, integrated atom trap (HG-IAT) atomizer flame absorption spectrometry (FAAS) systems were evaluated for the speciation analysis of antimony in environmental samples. Antimony, using formation of stibine (SbH3) vapors were atomized in an air–acetylene flame-heated IAT. A new design of HG-IAT-FAAS hyphenated technique that would exceed the operational capabilities of existing arrangements (a water-cooled single silica tube, double-slotted quartz tube or an “integrated trap”) was investigated. For the estimation of Sb(III) and Sb(V) concentrations in samples, the difference between the analytical sensitivities of the absorbance signals obtained for antimony hydride without and with previous treatment of samples with L-cysteine can be used. The concentration of Sb(V) was calculated by the difference between total Sbtot and Sb(III). A dramatic improvement in detection limit was achieved compared with that obtained using either of the atom trapping techniques, presented above, separately. This novel approach decreases the detection limit down to low pg mL–1 levels. The concentration detection limit, defined as 3 times the blank standard deviation (3sigma), was 0.2 ng mL–1. For a 120 s in situ pre-concentration time (sample volume of 2 mL), sensitivity enhancement compared to flame AAS, was 550 fold for Sb, using hydride generation-atom trapping technique. The sensitivity can be further improved by increasing the collection time. The precision, expressed by RSD, was 8.0% (n = 6) for Sb. The designs studied include slotted tube, water-cooled single silica tube and integrated atom traps. Reference and real sample materials were analyzed. The accuracy of the method was verified by the use of certified reference materials (NIST SRM 2704 Buffalo River Sediment, SRM 2710 Montana Soil, SRM 1633a Coal Fly Ash, SRM 1575 Pine Needles, SRM 1643e Trace Elements in Water) and by aqueous standard calibration technique (solutions). The measured Sb content, in reference materials, were in satisfactory agreement with the certified values. The hyphenated technique was applied for antimony determinations in soil, sediment, coal fly ash, sewage and river water.

Merging Zones FIA System for the Spectrophotometric Determination of Sb(III) and Total Sb in Drugs Used in the Treatment of Leishmaniasis

A merging zones flow injection system was developed for the spectrophotometric determination of Sb(III) and Sb(V) in drugs used in the treatment of leishmaniasis. The procedure is based on the selective reaction between Sb(III) and bromopyrogallol red (BPR) with the decrease of the absorbance measured at 555 nm. The concentration of Sb(V) was calculated by difference after determination of total antimony. Influences of chemical and flow parameters such as pH of reaction, BPR concentration, surfactant concentration, carrier and reagent flow rates, loop volume, and coil reactor length were critically evaluated. Selectivity of the method and the suitable conditions for sample preparation before injection were investigated. The obtained results demonstrated that the addition of Triton X‐100 enhanced the sensitivity of the method due to acceleration of the chromogenic reaction. Working on optimized conditions, the detection (3σ) and quantification (10σ) limits were 30 ng mL−1 and 100 ng mL−1, respectively. The RSD observed at 0.25 µg mL−1 was 4.0% and the analytical throughput was 90 hr−1. Three samples of commercial drugs were analyzed according to the developed procedure not presenting any statistical difference in relation to the results obtained by FAAS for total antimony concentration. The authors were invited to contribute this paper to a special issue of the journal entitled “Spectroscopy and Automation”. This special issue was organized by Miguel de la Guardia, Professor of Analytical Chemistry at Valencia University, Spain.

Determination of total antimony and antimony(V) by inductively coupled plasma mass spectrometry after selective separation of antimony(III) by solvent extraction with N-benzoyl- N-phenylhydroxylamine

The study of antimony speciation in various types of natural water from the area of Warsaw city was performed. For this purpose the simple, fast and specific analytical method of determination of total inorganic antimony and antimony(V) in aqueous phase of the sample by inductively coupled plasma mass spectrometry (ICP-MS) was developed. The procedure is based on selective removal of antimony(III) by solvent extraction with N-benzoyl- N-phenylhydroxylamine. The concentration of Sb(III) was calculated as a difference between total antimony and Sb(V) concentrations. The detection limit achieved by described procedure in combination with ICP-MS detection was 0.7 ng l −1. The relative standard deviations for analysis of three samples containing 0.028–0.915 μg l −1 of total antimony and 0.027–0.894 μg l −1 of Sb(V) ranged from 0.46 to 2.9% and 0.60 to 3.7%, respectively. The antimony concentration in all samples analyzed was less than 1 μg l −1. Speciation studies revealed that in natural waters the prevailing chemical form is antimony(V). The on-field separation of both forms of antimony assures stabilization of speciation at the site of sampling.

Determination of total available antimony in marine sediments by slurry formation–hydride generation atomic absorption spectrometry. Applicability to the selective determination of antimony(III) and antimony(V)

A method is described for the determination of total antimony, extractable into 4 mol dm–3 HCl, and SbIII, which combines a slurry procedure with hydride generation atomic absorption spectrometry. The lack of a matrix effect allows the analytical results to be obtained with a simple aqueous working curve. The detection limit in solid samples is 13.3 and 8.35 ng g–1 for SbIII and total antimony, respectively. The proposed method for the determination of total antimony provides a better recovery than that obtained by digestion with a mixture of HNO3–H2SO4–HClO4 but worse than that obtained by digestion with HF.

Semi-automated determination of antimony in rocks

A simple, rapid and accurate method for the determination of total antimony in rock samples is described. An automated hydride generation procedure is used to generate stibine gas from solutions of rock samples prepared by digestion with a mixture of hydrofluoric and sulfuric acids. The evolved hydride is carried to a heated quartz tube by an argon stream and the atomic absorption of antimony recorded. The method is practically free from interferences. As little as 0.08 μg Sb g -1 can be determined; the average r.s.d. over the range 0.16–4.5 μg g -1 is 6.5%. Close agreement is obtained between results obtained on 14 U.S. Geological survey rocks by this method and those reported by neutron activation analysis.