Simultaneous hyperaccumulation of arsenic and antimony in Cretan brake fern: Evidence of plant uptake and subcellular distributions

Arsenic (As) and antimony (Sb) show similar chemical properties and often present together in sulfide ores. Currently, phenomenon of co-contamination of As and Sb at some sites of the world has been increasingly emerged. The present study was conducted to explore the potential of Pteris cretica L. (Cretan brake fern), an arsenic (As) hyperaccumulator, to simultaneously accumulate As and Sb under hydroponic conditions. Arsenic was imposed at medium and high levels of 5 mg L^− 1 and 20 mg L^− 1, while Sb was imposed either single or co-presence with As at medium and high levels of 10 mg L^− 1 and 20 mg L^− 1, with no As and Sb addition as the control. The single and interactive effects of As and Sb on their uptake and subcellular distributions were analyzed. Cretan brake fern could accumulate high concentrations of As and Sb, with the highest concentrations of As and Sb been recorded as 1677.2 mg kg^− 1 and 1516.5 mg kg^− 1 in the fronds, respectively. Arsenic and Sb were found mainly in cytosol, while less in cell wall and cytoplasmic organelles. Sb uptake by Cretan brake fern was enhanced with increasing As levels, which was accompanied with an increase of Sb but a decrease of As in cytosol fractions. Arsenic uptake was slightly enhanced whereas suppressed when Sb was co-present in a medium and high level, respectively; however, in both conditions, As was found to be decreased in cytosol of the above ground parts as fronds and stems of Cretan brake fern. The results demonstrate Cretan brake fern can simultaneously hyperaccumulate As and Sb, thus is valued in phytoremediation of As and Sb co-contamination.     

Detoxification of antimony by selenium and their interaction in paddy rice under hydroponic conditions

Antimony (Sb) contamination has become a growing concern in recent years. Strategies for reducing Sb contamination and its related health risks are urgently desired. This study was conducted to explore the possibility of selenium (Se) detoxification on Sb toxicity in paddy rice in order to find a feasible method to reduce the health risk of Sb pollution. Seedlings of paddy rice were exposed to 5 mg L⁻¹ Sb (KSbC₄H₄ O₇·1/2H₂O), in the presence of Se (Na₂SeO₃) at 0.1, 1, 5 mg L⁻¹ in culture solution, with no Sb and Se addition as the control. Paddy rice took up Sb greatly and the highest Sb contents measured among all treatments in this experiment in the leaves, stems and roots were 65.5, 298.5 and 195.7 mg kg⁻¹, respectively. Without Sb addition in the solution, single exposure to 0.1 mg L⁻¹ Se remarkably reduced the malondialdehyde (MDA) formation in paddy rice,demonstrating the beneficial effect of Se at low dosages. The addition of 5 mg L⁻¹ Sb was found to generate toxicity to paddy rice, showing as decreased biomass and increased leaf MDA content in paddy rice, while addition of 1 mg L⁻¹ Se mitigated the toxicity of Sb, as seen with the decreased leaf MDA content and increased biomass, indicating antidotal role of Se to Sb. In addition, the presence of 0.1, 1, 5 mg L⁻¹ Se generally decreased the accumulation of Sb in the leaves, stems and roots in paddy rice. Toxicity was also seen when paddy rice was exposed to single Se at 1 and 5 mg L⁻¹ levels, however, 5 mg L⁻¹ Sb addition was found to decrease the contents of Se in the leaves/stems whereas increased them in roots, accompanied with decreased MDA contents and increased biomass in paddy rice, indicating a possible detoxification role of Sb to Se too. Therefore, Sb, although toxic, could also be an antitoxin to Se in paddy rice at certain condition. Our results showed that Se could alleviate Sb toxicity efficiently in paddy rice through two effects as antagonism and antioxidation.     

Bioaccumulation of antimony, arsenic, and mercury in the vicinities of a large antimony mine, China

To study the characteristics of antimony (Sb) bioaccumulation under high Sb background values, aquatic, amphibious and terrestrial biological samples were collected in the vicinity of the Xikuangshan (XKS) Sb mine area in China. Hydride generation-atomic fluorescence (HG-AFS) analysis showed that Sb concentrations in terrestrial invertebrates (average 30,400 μg kg^− 1 dry wt.) were higher than those in aquatic (average 5200 μg kg^− 1 dry wt.) and amphibian (average 2300 μg kg^− 1 dry wt.) biological samples. Within 1 km distance of the XKS Sb mine area, grasshoppers (Acrida chinensis) and earthworms (Pheretima aspergillum) had the highest Sb amounts of 17,300 ±3200 and 43,600 ± 47,700 μg kg^− 1 dry wt., respectively. No Sb biomagnifications were observed. The bioavailability of Sb was found to be lower than those of As and Hg. A preliminary conclusion is that antagonistic effects exist between Sb and Hg accumulation in biological samples from aquatic environments. Our study is the first to report such antagonistic effects between Sb and Hg. If this deduction proves to be correct, it should be taken into consideration in assessing human health risks, especially when Sb and Hg concentrations in the aquatic environments are high.     

Simultaneous determination of trace arsenic(III), antimony(III), total arsenic and antimony in Chinese medicinal herbs by hydride generation-double channel atomic fluorescence spectrometry

A new method was developed for simultaneous determination of trace arsenic and antimony in Chinese herbal medicines by hydride generation-double channel atomic fluorescence spectrometry with a Soxhlet extraction system and an n-octanol-water extraction system, respectively. The effects of analytical conditions on the fluorescence intensity were investigated and optimized. A water-dissolving and methanol-water-dissolving capability were compared. The contents of different species in five Chinese herbal medicines and their decoctions were analyzed. The concentration ratios of n-octanol-soluble As or Sb to water-soluble As or Sb were related to the kinds of medicine and the acidity of the decoction. Soxhlet extraction was found to be an effective method for plants pretreatment for determination of arsenic and antimony species in Chinese herbs; the interferences of coexisting ions were evaluated. The proposed method has the advantages of simple operation, high sensitivity and high speed, with 3σ detection limits of 0.094 μg g⁻¹ for As(III), 0.056 μg g⁻¹ for total As, 0.063 μg g⁻¹ for Sb(III) and 0.019 μg g⁻¹ for total Sb in a 1.0 g of the sample.     

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.     

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.     

Distribution and accumulation of antimony in plants in the super-large Sb deposit areas, China

Antimony (Sb) distribution and accumulation in plants in Xikuangshan Sb deposit area, the only one super-large Sb deposit in the world, Hunan, China were investigated. Results show that soils were severely polluted with the average Sb concentrations up to 5949.20 mg kg^− 1. Sb widely occurred in 34 plants with various concentrations ranging from 3.92 mg kg⁻¹ to 143.69 mg kg^− 1, Equisetaceae family has the highest concentration (98.23 mg kg^− 1) while Dryopteridacea family has the lowest one (6.43 mg kg^− 1). H. ramosissima species of Equisetaceae family had the highest Sb average concentration of 98.23 mg kg^− 1 and P. vittata species of Pteridaceae family showed advantage of accumulating Sb from the contaminated environment (Biological Accumulation Coefficient, BAC = 0.08). Almost all species enriched Sb in their upground part such as shoot, leaf and flower (Biological Transfer Coefficient, BTC > 1), which may attribute to the high acropetal coefficient and Sb transformation from the atmosphere to the plants. P. phaseoloides and D. indicum showed predominantly accumulation of Sb in the upground part with BTC of 6.65 and 5.47, respectively.From the low bioavailable fraction in soils and weak relationship between total soil concentrations in soils and plants, it seems that the Sb bioavailability was limited and varied with different soil sites as well as plant species. Those observations would be significant to the phytoaccumulation and phytoremediation of plants and ecological and environmental risk assessment in Sb contaminated areas.     

Flow analysis-hydride generation-Fourier transform infrared spectrometric determination of antimony in pharmaceuticals

In this work, a flow analysis system with hydride generation and Fourier transform infrared (FTIR) spectrometric detection has been developed for the determination of antimony in pharmaceuticals. The method is based on the on-line mineralization/oxidation of the organic antimonials present in the sample and pre-reduction of Sb(V) to Sb(III) with K₂S₂O₈ and KI, respectively; prior to the stibine generation. The gaseous SbH₃ is separated from the solution in a gas phase separator, and transported by means of a nitrogen carrier into a short pathway (10 cm) IR gas cell, where the corresponding FTIR spectrum is acquired by accumulating 3 scans in a continuous mode. The 1893 cm⁻¹ band was used for the quantification of the antimony. The procedure is carried out in a closed system, which reduces sample handling and makes possible the complete automation of the antimony determination. The figures of merit of the proposed method (linear range: 0-600 mg l⁻¹, limit of detection (3σ)=0.9 mg l⁻¹, limit of quantification (10σ)=3 mg Sb l⁻¹, precision (R.S.D.) less than 1% and sample frequency=28 h⁻¹), are appropriate for the designed application. Furthermore, precise and accurate results were found for the analysis of different antimonial pharmaceutical samples, indicating that the methodology developed represents a valid alternative for the determination of antimony in pharmaceuticals, which could be suitable for the routine control analysis.     

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.     

Optimization of chemical and instrumental parameters in hydride generation laser-induced breakdown spectrometry for the determination of arsenic,antimony, lead and germanium in aqueous samples

A laser induced breakdown spectrometry hyphenated with on-line continuous flow hydride generation sample introduction system, HG-LIBS, has been used for the determination of arsenic, antimony, lead and germanium in aqueous environments. Optimum chemical and instrumental parameters governing chemical hydride generation, laser plasma formation and detection were investigated for each element under argon and nitrogen atmosphere. Arsenic, antimony and germanium have presented strong enhancement in signal strength under argon atmosphere while lead has shown no sensitivity to ambient gas type. Detection limits of 1.1 mg L⁻¹, 1.0 mg L⁻¹, 1.3 mg L⁻¹ and 0.2 mg L⁻¹ were obtained for As, Sb, Pb and Ge, respectively. Up to 77 times enhancement in detection limit of Pb were obtained, compared to the result obtained from the direct analysis of liquids by LIBS. Applicability of the technique to real water samples was tested through spiking experiments and recoveries higher than 80% were obtained. Results demonstrate that, HG-LIBS approach is suitable for quantitative analysis of toxic elements and sufficiently fast for real time continuous monitoring in aqueous environments.     

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.     

Speciation of antimony by adsorptive stripping voltammetry using pyrogallol

This paper describes a new procedure for the determination of Sb (III) and Sb (V) by differential pulse adsorptive stripping voltammetry (DPAdSV) using pyrogallol as a complexing agent. The selection of the experimental conditions was made using experimental design methodology. The detection limits obtained were 1.03 × 10⁻¹⁰ and 9.48 × 10⁻⁹ mol dm⁻³ for Sb (III) and Sb (V), respectively.In order to carry out the simultaneously determination of both antimony species a partial least squares regression (PLS) is employed to resolve the voltammetric signals from mixtures of Sb (III) and Sb (V) in the presence of pyrogallol. The relative error in absolute value is less than 0.5% when concentrations of several mixtures are calculated. Moreover, the solution is analyzed for any possible effects of foreign ions. The procedure is successfully applied to the speciation of antimony in pharmaceutical preparations and water samples.     

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 methylmercury and estimation of total mercury in seafood using high performance liquid chromatography (HPLC) and inductively coupled plasma-mass spectrometry (ICP-MS): Method development and validation

A method was developed for determination of methylmercury and estimation of total mercury in seafood. Mercury (Hg) compounds were extracted from 0.5 g edible seafood or 0.2 g lyophilized reference material by adding 50 ml aqueous 1% w/v l-cysteine·HCl·H₂O and heating 120 min at 60 °C in glass vials. Hg compounds in 50 μl of filtered extract were separated by reversed-phase high performance liquid chromatography using a C-18 column and aqueous 0.1% w/v l-cysteine·HCl·H₂O + 0.1% w/v l-cysteine mobile phase at room temperature and were detected by inductively coupled plasma-mass spectrometry at mass-to-charge ratio 202. Total Hg was calculated as the mathematical sum of methyl and inorganic Hg determined in extracts. For seafoods containing 0.055-2.78 mg kg⁻¹ methylmercury and 0.014-0.137 mg kg⁻¹ inorganic Hg, precision of analyses was ≤5% relative standard deviation (R.S.D.) for methylmercury and ≤9% R.S.D. for inorganic Hg. Recovery of added analyte was 94% for methylmercury and 98% for inorganic Hg. Methyl and total Hg results for reference materials agreed with certified values. Limits of quantitation were 0.007 mg kg⁻¹ methylmercury and 0.005 mg kg⁻¹ inorganic Hg in edible seafood and 0.017 mg kg⁻¹ methylmercury and 0.012 mg kg⁻¹ inorganic Hg in lyophilized reference materials. Evaluation of analyte stability demonstrated that l-cysteine both stabilized and de-alkylated methylmercury, depending on holding time and cysteine concentration. Polypropylene adversely affected methylmercury stability. Total Hg results determined by this method were equivalent to results determined independently by cold vapour-atomic absorption spectrometry. Methylmercury was the predominant form of Hg in finfish. Ratios of methylmercury/total Hg determined by this method were 93-98% for finfish and 38-48% for mollusks.     

A rapid quantitative method for humic substances determination in natural waters

A simple and rapid method was proposed for humic substances (HS) determination at microgram levels in natural waters. This assay method is based on the binding of a dye, Toluidine Blue (TB), to HS molecules to produce a dye-HS complex, which causes a decrease in absorbance at 630 nm. This method was calibrated with HS samples with up to a concentration of 40 mg L⁻¹, which covered the range of dissolved HS concentrations present in natural waters. The detection limit was 0.8 mg L⁻¹ of HS, and the relative standard deviation of 10 replicate measurements for a 20-mg L⁻¹ standard sample was 3.5%. From the Langmuir adsorption isotherm theory, the binding equilibrium constant and total number of binding sites at neutral pH were calculated to be (8.17 ± 0.42) × 10⁵ L mol⁻¹ and N of 1.45 ± 0.04 mmol g⁻¹ HS, respectively. The determination results with five water samples from lake, river and pond were consistent with those measured with the reference methods, demonstrating that this quantification method for HS determination was rapid, sensitive and feasible.     

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 metal content in some herbal drugs-Empirical and chemometric approach

The concentrations of Cu, Zn, Mn, Fe, K, Ca, Mg, Al, Ba and B in 26 herbal drugs of special importance in phytopharmacy were studied. Flame atomic absorption and emission spectrometry (FAAS, FAES), as well as inductively coupled plasma atomic emission spectrometry (ICP-AES), were applied in this work. The whole procedure, from sample preparation, via dissolution, to measurements, was validated by using CRM (NIST 1573a—tomato leaves), and the obtained recovery values are in the range from 91 to 102%. Drug samples originated from medicinal plants cultivated in Serbia contained Cu (4.47-14.08 mg kg⁻¹), Zn (8.4-54.5 mg kg⁻¹), Mn (9-155 mg kg⁻¹), Fe (47-546 mg kg⁻¹), K (0.20-6.24%), Ca (0.18-1.84%), Mg (0.13-1.09%), Al (16-416 mg kg⁻¹), Ba (11.70-84.83 mg kg⁻¹) and B (5.1-118.7 mg kg⁻¹). In order to get a better insight into the elemental patterns, a common chemometric approach to data evaluation was used. Four significant factors identified by principal component analysis (PCA) were attributed partly to the significant influential sources and high mobility of some elements thus referring to potential anthropogenic contamination as well.     

Accurate screening for synthetic preservatives in beverage using high performance liquid chromatography with time-of-flight mass spectrometry

In this study, liquid chromatography time-of-flight mass spectrometry (HPLC/TOF-MS) is applied to qualitation and quantitation of 18 synthetic preservatives in beverage. The identification by HPLC/TOF-MS is accomplished with the accurate mass (the subsequent generated empirical formula) of the protonated molecules [M + H]+ or the deprotonated molecules [M − H]−, along with the accurate mass of their main fragment ions. In order to obtain sufficient sensitivity for quantitation purposes (using the protonated or deprotonated molecule) and additional qualitative mass spectrum information provided by the fragments ions, segment program of fragmentor voltages is designed in positive and negative ion mode, respectively. Accurate mass measurements are highly useful in the complex sample analyses since they allow us to achieve a high degree of specificity, often needed when other interferents are present in the matrix. The mass accuracy typically obtained is routinely better than 3 ppm. The 18 compounds behave linearly in the 0.005-5.0 mg·kg⁻¹ concentration range, with correlation coefficient >0.996. The recoveries at the tested concentrations of 1.0 mg·kg⁻¹-100 mg·kg⁻¹ are 81-106%, with coefficients of variation <7.5%. Limits of detection (LODs) range from 0.0005 to 0.05 mg·kg⁻¹, which are far below the required maximum residue level (MRL) for these preservatives in foodstuff. The method is suitable for routine quantitative and qualitative analyses of synthetic preservatives in foodstuff.     

Inter-method comparison for the determination of antimony and arsenic in peat samples

Four analytical approaches, based on different physical principles, for the determination of antimony (Sb) and arsenic (As) in ancient peat samples were critically evaluated: (a) open vessel digestion/hydride generation-atomic absorption spectrometry (HG-AAS), (b) closed-pressurized digestion in a microwave oven followed by sector field-inductively coupled plasma-mass spectrometry (SF-ICP-MS), (c) digestion in a microwave autoclave and subsequent quadrupole-inductively coupled plasma-mass spectrometry (Q-ICP-MS) measurements and (d) instrumental neutron activation analysis (INAA). The quality control scheme applied, always included the use of adequate plant reference materials to ensure the accuracy and precision of the analytical procedures. Additionally, two internal peat reference materials were analyzed using all four analytical approaches, generally showing good agreement for both elements. Method detection limits for As and Sb provided by all procedures were approximately 5 and 2 ng g⁻¹ which is sufficiently low for the reliable quantification of both elements in ancient, pre-anthropogenic peat samples. A comparison of As and Sb concentrations in a set of peat samples determined by INAA, HG-AAS and SF-ICP-MS revealed that INAA underestimated the values in a systematic manner, whereas HG-AAS and SF-ICP-MS data agreed very well. Best precision of the results was obtained by analytical procedures involving HG-AAS or Q-ICP-MS and varied from 3.6 to 4.3% and 7.1 to 7.5% for As (at about 0.5 μg g⁻¹) and Sb (at about 0.1 μg g⁻¹), respectively. The highest sample throughput (40 samples per run accomplished in 2 h) combined with low risk of sample contamination could be realized in the high-pressure microwave autoclave. The amount of sample required by all approaches was 200 mg, except for INAA which needed at least 25 times more sample mass to achieve comparable detection limits. For the quantification of As and Sb, inductively coupled plasma-mass spectrometry (ICP-MS) was preferred over INAA and HG-AAS, mainly because (a) less sample is needed and (b) As and Sb can be determined simultaneously. In addition, ICP-MS offers the possibility to measure concurrently a wide range of other elements which also are of environmental interest.     

Determination of inorganic antimony species in seawater by differential pulse anodic stripping voltammetry: stability of the trivalent state

A simple method is described for the rapid and reliable determination of ultratrace concentrations of Sb(III) and Sb(V) in seawater by differential pulse anodic stripping voltammetry. It is based on the well-known dependence of Sb(III)/Sb(V) voltammetric response on acidity conditions. Under our optimised conditions (0.5 mol l⁻¹ HCl for Sb(III) and 5 mol l⁻¹ HCl for total Sb, respectively): (i) a detection limit of 11 ng l⁻¹ is obtained for a 10 min deposition time; (ii) no prior elimination of organic matter is needed; and (iii) antimony can be determined in the presence of natural copper levels. Particular care has been taken in order to understand the chemical processes taking place in all the solutions and reactions involved in the sampling and measuring procedures. Our results revealed the need to consider (i) the effect of photooxydation of synthetic and seawater samples on Sb speciation; and (ii) the stability of Sb(III) both in seawater samples and in the analytical solutions.