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).     

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.     

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.     

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%.     

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.     

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 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 an analytical method for antimony speciation in vegetables by HPLC-hydride generation-atomic fluorescence spectrometry

A new method for antimony speciation in terrestrial edible vegetables (spinach, onions, and carrots) was developed using HPLC with hydride generation-atomic fluorescence spectrometry. Mechanical agitation and ultrasound were tested as extraction techniques. Different extraction reagents were evaluated and optimal conditions were determined using experimental design methodology, where EDTA (10 mmol/L, pH 2.5) was selected because this chelate solution produced the highest extraction yield and exhibited the best compatibility with the mobile phase. The results demonstrated that EDTA prevents oxidation of Sb(III) to Sb(V) and maintains the stability of antimony species during the entire analytical process. The LOD and precision (RSD values obtained) for Sb(V), Sb(III), and trimethyl Sb(V) were 0.08, 0.07, and 0.9 microg/L and 5.0, 5.2, and 4.7%, respectively, for a 100 microL sample volume. The application of this method to real samples allowed extraction of 50% of total antimony content from spinach, while antimony extracted from carrots and onion samples ranged between 50 and 60 and 54 and 70%, respectively. Only Sb(V) was detected in three roots (onion and spinach) that represented 60-70% of the total antimony in the extracts.     

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).     

Speciation of dissolved inorganic antimony in natural waters using liquid phase semi-microextraction combined with electrothermal atomic absorption spectrometry

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.     

Determination of arsenic and antimony in electrolytic copper by anodic stripping voltammetry at a gold film electrode

A simple procedure is described for the determination of arsenic and antimony in electrolytic copper. The copper is digested with nitric acid and copper is separated from arsenic and antimony by passing an ammoniacal solution of the sample through a column of Chelex-100 resin. After digestion with sulphuric acid and reduction to arsenic(III) and antimony(III) with sodium sulphite in 7 M sulphuric acid at 80°C, both arsenic and antimony are deposited at-0.30V and their total is determined by anodic stripping; antimony is then selectively deposited at -0.05 V for anodic stripping. The lower limits of determination are 56 ng As and 28 ng Sb per gram of copper; relative standard deviations (n = 5) are in the ranges 6.1–15.0% for 5.5—0.5 ppm arsenic in copper and 4.1–6.8% for 2.6—0.6 ppm antimony.     

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.     

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.     

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.     

Speciation of antimony by atomic absorption spectrometry. Applicability to selective determination of Sb(III) and Sb(V) in liquid samples and of bioavailable antimony in sediments and soil samples

A comparative study was made of several methods to speciale Sb(III) and Sb(V) by AAS: 1) Selective extraction of Sb(III) with lactic acid/malachite green graphite furnace-AAS, 2) Sb(III) and total antimony determination by hydride generation-AAS coupled to flow injection, batch, and continuous flow systems. These methods were applied to determine total antimony and Sb(III) in sea and surface water and total antimony in sediments and in soil. For soils different sample pretreatments were used: HNO₃-H₂SO₄-HC1O₄, HF-HNO₃-H₂SO₄-HC1O₄, cold aqua regia and slurry formation procedures in water and 4M HC1. In each case the recovery of total antimony and the ability to selective determine Sb(III) were studied. The detection limits obtained were 0.01 ng, 0.07 ng, 2.97 ng and 0.21 ppb for GF-AAS, FIA-HG-AAS, HG (Batch)-AAS, and HG (continuous flow)-AAS, respectively.     

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.     

Determination of antimony(III,V) in natural waters by separation and preconcentration on a thionalide loaded resin followed by neutron activation analysis

A chelating sorbent obtained by immobilization of thionalide on the macroporous resin Bio Beads SM-7 was used for speciation of antimony(III) and (V) in natural waters. Antimony(III) was separated from Sb(V) by sorption on a column with the sorbent at pH 5. Antimony(V) in the effluent was reduced to Sb(III) and preconcentrated by sorption on the sorbent from 0.5M HCl solution. Both the separated species were determined directly on the sorbent by neutron activation analysis.     

Speciation analysis of antimony in marine biota by HPLC-(UV)-HG-AFS: Extraction procedures and stability of antimony species

Speciation analysis of antimony in marine biota is not well documented, and no specific extraction procedure of antimony species from algae and mollusk samples can be found in the literature. This work presents a suitable methodology for the speciation of antimony in marine biota (algae and mollusk samples). The extraction efficiency of total antimony and the stability of Sb(III), Sb(V) and trimethylantimony(V) in different extraction media (water at 25 and 90 °C, methanol, EDTA and citric acid) were evaluated by analyzing the algae Macrosystis integrifolia (0.55 ± 0.04 μg Sb g⁻¹) and the mollusk Mytilus edulis (0.23 ± 0.01 μg Sb g⁻¹). The speciation analysis was performed by anion exchange liquid chromatography (post-column photo-oxidation) and hydride generation atomic fluorescence spectrometry as detection system (HPLC-(UV)-HG-AFS). Results demonstrated that, based on the extraction yield and the stability, EDTA proved to be the best extracting solution for the speciation analysis of antimony in these matrices. The selected procedure was applied to antimony speciation in different algae samples collected from the Chilean coast. Only the inorganic Sb(V) and Sb(III) species were detected in the extracts. In all analyzed algae the sum of total antimony extracted (determined in the extracts after digestion) and the antimony present in the residue was in good agreement with the total antimony concentration determined by HG-AFS. However, in some extracts the sum of antimony species detected was lower than the total extracted, revealing the presence of unknown antimony species, possibly retained on the column or not detected by HPLC-(UV)-HG-AFS. Further work must be carried out to elucidate the identity of these unknown species of antimony.     

Application of ultrasonic-assisted cloud point extraction/flame atomic absorption spectrometry (UA-CPE/FAAS) for preconcentration and determination of low levels of antimony in some beverage samples

Due to be able to migrate or leach from food packaging materials into the foods and/or beverages, development of a new, sensitive and selective analytical methods for low levels of antimony as a food contaminant is of great importance in terms of food safety. In this context, an ultrasonic-assisted cloud point extraction method was developed for the preconcentration and determination of antimony as Sb(III) using 4-(2-thiazolylazo)resorcinol (TAR) and 2-(2-thiazolylazo)-p-cresol (TAC) as chelating agents and sodium dodecyl sulfate as signal enhancing agent at pH 6.0 and mediated by nonionic surfactant, t-octylphenoxypolyethoxyethanol by flame atomic absorption spectrometry. Using the optimized conditions, the calibration curves obtained from Sb(III) with TAR and TAC were linear in the concentration ranges of 0.5–180 and 1–180 μg L^?1 with detection limits of 0.13 and 0.28 μg L^?1, respectively. The precision (as relative standard deviations, RSDs) was lower than 3.9 % (25 and 100 μg L^?1, n: 6). The method accuracy was validated by the analysis of two standard reference materials. The results obtained were statistically in a good agreement with the certified values at 95 % confidence limit. The method has successfully been applied to the determination of Sb(III) and total Sb in selected beverages, milk and fruit-flavored milk products before and after pre-reduction of Sb(V) to Sb(III) with a mixture of KI/ascorbic acid in acidic media. The Sb(V) contents of samples were quantitatively calculated from analytical difference between total Sb and Sb(III) levels.