Speciation analysis of inorganic antimony in soil using HPLC-ID-ICP-MS

Stimulated leaching of metalloids along 3D-printed fractured rock vadose zone

Fractured rock aquifers are susceptible to contamination, with metal(loid)s rapidly migrating from poorly developed overburden to the fractured rock vadose zone and thus into groundwater. Compared to typical porous aquifers, retention effects within the rock matrix are small, and rapid advection along fractures leads to a higher risk of groundwater contamination. However, the highly complex anisotropic pathways of natural fractures hinder research in this field. To construct reproducible fractures, this study used 3D printing following Computed X-ray Microtomography (μCT) scans of a fractured rock collected in a natural limestone aquifer. Stimulated metalloid release was observed in the fractured rock during column leaching, and the leachate concentrations of arsenic (As) and antimony (Sb) increased by up to 17.5 and 36.4 times, respectively, compared with the porous vadose zone. Fluctuations in fracture metalloid release patterns in dissolved and adsorbed phases were attributed to retention and filtration effects induced by soil particles within fractures. Geophysical properties of the porous overburden, especially the aggregation characteristics, greatly affected the non-equilibrium leaching behavior of As, but had a limited effect on the near-equilibrium leaching of Sb, which was explored by modifying the surficial soil layer with either montmorillonite clay or charcoal. The results of this study provide a novel method and useful information for modeling and risk assessment of fractured rock aquifers.

Simple and Fast Two-Step Fully Automated Methodology for the Online Speciation of Inorganic Antimony Coupled to ICP-MS

A very simple, fast and non-chromatographic methodology for inorganic antimony speciation based on Multisyringe Flow Injection Analysis (MSFIA) employing online hydride generation (HG) ICP-MS was developed. The fully automated analysis is performed in two steps: firstly, Sb(III) is quantified by ICP-MS after chemical vapor generation; then, total antimony is determined in the presence of potassium iodide as a pre-reducer of Sb(V) to Sb(III). The Sb(V) concentration is quantified by the difference between the total antimony and Sb(III) concentrations, reaching an analysis frequency of 30 h−1. The optimization was performed using a Box Behnken design. The MSFIA-HG-ICP-MS system allows the antimony speciation analysis with a detection limit of 0.016 µg L−1 for Sb(III), working in a linear range of 0.053 to 5.0 µg L−1. This method was applied for the determination of Sb(III) and Sb(V) in water samples from Maiorca Island, Spain, and the concentrations found varied from 0.10 to 0.14 µg L−1 for Sb(III) and from 0.12 to 0.28 µg L−1 for Sb(V). The results were validated by addition/recovery tests, obtaining recoveries between 90 and 111% in both cases. Furthermore, a good precision was achieved, 1.4% RSD, and sample and reagent consumption were reduced to a few mL, with the consequent decrease in waste generation. Thus, the proposed method is a good tool for the speciation of inorganic antimony at ultra-trace levels in waters, allowing its risk assessment.

Analytical Methodologies for Agrometallomics: A Critical Review

Agrometallomics, as an independent interdiscipline, is first defined and described in this review. Metallic elements widely exist in agricultural plants, animals and edible fungi, seed, fertilizer, pesticide, feedstuff, as well as the agricultural environment and ecology, and even functional and pathogenic microorganisms. So, the agrometallome plays a vital role in molecular and organismic mechanisms like environmetallomics, metabolomics, proteomics, lipidomics, glycomics, immunomics, genomics, etc. To further reveal the inner and mutual mechanism of the agrometallome, comprehensive and systematic methodologies for the analysis of beneficial and toxic metals are indispensable to investigate elemental existence, concentration, distribution, speciation, and forms in agricultural lives and media. Based on agrometallomics, this review summarizes and discusses the advanced technical progress and future perspectives of metallic analytical approaches, which are categorized into ultrasensitive and high-throughput analysis, elemental speciation and state analysis, and spatial- and microanalysis. Furthermore, the progress of agrometallomic innovativeness greatly depends on the innovative development of modern metallic analysis approaches including, but not limited to, high sensitivity, elemental coverage, and anti-interference; high-resolution isotopic analysis; solid sampling and nondestructive analysis; metal chemical species and metal forms, associated molecular clusters, and macromolecular complexes analysis; and metal-related particles or metal within the microsize and even single cell or subcellular analysis.

Determination of antimony compounds in waters and juices using ion chromatography-inductively coupled plasma mass spectrometry

A method was developed by coupling ion chromatography (IC) and inductively coupled plasma mass spectrometry (ICP-MS) for the speciation of antimony. In this study, antimony species such as antimonite [Sb(III)], antimonate [Sb(V)] and trimethyl antimony(V) (TMeSb) were separated in less than 8min using anion exchange chromatography with a Hamilton PRP-X100 column as the stationary phase. Mobile phase A was 20mmolL^-1 ethylenediaminetetraacetic acid (EDTA), 2mmolL^-1 potassium hydrogen phthalate (KHP) in 1% v/v methanol (pH 5.5) and 20mmolL^-1 EDTA, 2mmolL^-1 KHP, 40mmolL^-1 (NH₄)₂CO₃ in 1% v/v methanol (pH 9.0) formed mobile phase B. Detection limits and relative standard deviations (RSD) were 0.012-0.032ngmL^-1 and 2.2-2.8% respectively. This method was applied to bottled waters and fruit juices purchased in Kaohsiung, Taiwan. In water samples, Sb(V) was the major species where as in juices organometallic Sb species were also present.

Effect of cropping systems on heavy metal distribution and mercury fractionation in the Wanshan mining district, China: implications for environmental management

The authors studied the concentration of heavy metals and mercury fractionation in contaminated soil in 2 agricultural land use systems (paddy rice and dry land) at the Wanshan mercury mine in China. The average concentrations of chromium, lead, copper, nickel, and zinc were generally lower in paddy rice soil relative to corn field soil. Soil under corn field production was slightly contaminated with lead (22-100 mg/kg), copper (31-64 mg/kg), and nickel (22-76 mg/kg) and moderately contaminated with zinc (112-635 mg/kg). In both soils, correlation of these metals with the titanium concentration in the soil indicates a geogenic origin for each metal (lead, r = 0.48; copper, r = 0.63; nickel, r = 0.47; zinc, r = 0.48). The mercury and antimony concentration in soil was high under both cropping systems, and future remediation efforts should consider the potential environmental risk presented by these metals. The concentration of bioavailable mercury in soil ranged from 0.3 ng/g to 11 ng/g across the 2 cropping systems. The majority of mercury (>80%) was associated with organic matter and the residual fraction. However, soil under paddy rice production exhibited a significantly lower concentration of Fe/Mn oxide-bound mercury than that under corn field production. This may be a function of the reduction of Fe/Mn oxides in the paddy rice soil, with the subsequent release of adsorbed metals to the soil solution. Sequential change from corn field to paddy rice production, as practiced in Wanshan, should therefore be avoided. Mercury adsorbed to Fe/Mn oxides in corn field soil potentially could be released into the soil solution and be made available for biomethylation under the flooded water management conditions of a rice paddy.

Application of hyphenated techniques in speciation analysis of arsenic, antimony, and thallium

Due to the fact that metals and metalloids have a strong impact on the environment, the methods of their determination and speciation have received special attention in recent years. Arsenic, antimony, and thallium are important examples of such toxic elements. Their speciation is especially important in the environmental and biomedical fields because of their toxicity, bioavailability, and reactivity. Recently, speciation analytics has been playing a unique role in the studies of biogeochemical cycles of chemical compounds, determination of toxicity and ecotoxicity of selected elements, quality control of food products, control of medicines and pharmaceutical products, technological process control, research on the impact of technological installation on the environment, examination of occupational exposure, and clinical analysis. Conventional methods are usually labor intensive, time consuming, and susceptible to interferences. The hyphenated techniques, in which separation method is coupled with multidimensional detectors, have become useful alternatives. The main advantages of those techniques consist in extremely low detection and quantification limits, insignificant interference, influence as well as high precision and repeatability of the determinations. In view of their importance, the present work overviews and discusses different hyphenated techniques used for arsenic, antimony, and thallium species analysis, in different clinical, environmental and food matrices.

Identification of Sb(V) Complexes in Biological and Food Matrixes and Their Stibine Formation Efficiency during Hydride Generation with ICPMS Detection

Several studies have described the synthetic preparation of Sb(V) complexes with organic ligands, but only recently was such a complex identified to exist in beverages stored in PET containers. In the present study, we have investigated by using HPLC-ICPMS and HPLC-ES-MS(/MS), the formation of Sb(V) complexes in various biological (urine) and food matrixes (yoghurt and juice) spiked with noncomplexed inorganic Sb(V). Our results show that Sb(V) complex formation is matrix dependent and that several Sb(V) complexes form to a considerable extent in these matrixes. The results also suggest that the existence of Sb(V) complexes in natural samples may have previously been overlooked due to analytical method limitations, mainly chromatographic, but also detection limitations when hydride generation is used. To overcome some of these limitations, we have developed chromatographic methods suitable for preserving Sb-organic ligand complexes during their separation. When applying this mild nondestructive chromatographic method, we were able to identify novel Sb complexes in yoghurt spiked with inorganic Sb(V), i.e., 1:1 Sb(V)-citrate, 1:1 Sb(V)-lactate, 1:2 Sb(V)-lactate, and other Sb(V)-lactate complexes. This is the first characterization of Sb(V)-lactate complexes. Detailed studies on the hydride generation (HG) efficiency of Sb(V) complexes showed that Sb(V) complexes of high stability, such as Sb(V)-citrate, Sb(V)-(adenosine)n and Sb(V)-(lactate)n (n = 1 or 2), are nondetectable by HG-ICPMS. Furthermore, Sb(V) complexes formed in natural biological and food matrixes were only partly detectable by HG-ICPMS, confirming limitations of analytical methods based on HG volatilization and subsequent stibine detection in natural samples containing complexing ligands with affinity toward Sb(V).

Antimony speciation in soil samples along two Austrian motorways by HPLC-ID-ICP-MS

Distribution of antimony and its inorganic species in soil samples along two traffic routes (A14, Rankweil and S36, Knittelfeld) in Austria was determined, since vehicle emissions are an important anthropogenic source of Sb in soil. The samples were taken along three parallel lines at about 0.2, 2 and 10 m distances from the edge of the road and in two depths range (0-5 and 5-10 cm from the soil surface). The optimized extraction was carried out using 100 mmol L(-1) citric acid at pH 2.08 applying an ultrasonic bath for 45 min at room temperature. Speciation analyses were done using on-line isotope dilution after a chromatographic separation of Sb species. Results of the two traffic routes confirmed significant accumulations of Sb at surface (0-5 cm depth) exceeding the natural background values by more than ten times at the S36 or four times at the A14. Concentrations of the extractable inorganic species decreased to natural background levels within a few meters from the edge of the traffic lane. The predominant Sb species was Sb(V). The Sb(III) concentrations at 5-10 cm depths range are nearly constant with distance from the edges of the two roads. Magnetic susceptibility data of all soil samples show the same distribution pattern as Sb and Sb(V) concentrations along the two traffic roads with an excellent correlation. This is an evidence for an anthropogenic source of Sb such as abrasions of motor vehicles surfaces or braking linings. The input of Sb and its inorganic species at one of the sampling sites (Knittelfeld) in samples taken in 2002 and in those taken recently (2005) was monitored. An increase in Sb (>or=30%), Sb(v)(>or=51%) and Sb(iii)(>or=10%) concentrations was only observed near the edge (<or=2 m) of the road.