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A novel method for the speciation and quantification of polysulfide anions and molecular sulfur in lithium polysulfide solutions in organic solvents is reported. The technique is based on hyphenation of highperformance liquid chromatography (HPLC) and inductively coupled plasma mass spectrometry (ICPMS). A sector-field mass-spectrometer was utilized which made it possible to quantify various sulfur compounds without the need for single component standards and conduct the direct detection of the main isotope of sulfur regardless of interferents such as highly abundant 16O2. Key aspects of separation and sample preparation were considered which allowed complete separation of derivatized polysulfide anions. Gradual adjustment of essential parameters and hardware is described. Variation of plasma settings allowed for obtaining chromatograms with desired analyte peak shapes. The optimized method was applied for the quantification of various lithium polysulfide mixtures in organic solvents showing the accessibility of the corresponding polysulfide distributions with this technique. [ABSTRACT FROM AUTHOR]

This is the 16th Atomic Spectrometry Update (ASU) to focus on advances in elemental speciation and covers a period of approximately 12 months from January 2023. This ASU review deals with all aspects of the analytical atomic spectrometry speciation methods developed for: the determination of oxidation states; organometallic compounds; coordination compounds; metal and heteroatom-containing biomolecules, including metalloproteins, proteins, peptides and amino acids; and the use of metal-tagging to facilitate detection via atomic spectrometry. As with all ASU reviews the focus of the research reviewed includes those methods that incorporate atomic spectrometry as the measurement technique. However, because speciation analysis is inherently focused on the relationship between the metal(loid) atom and the organic moiety it is bound to, or incorporated within, atomic spectrometry alone cannot be the sole analytical approach of interest. For this reason, molecular detection techniques are also included where they have provided a complementary approach to speciation analysis. The number of publications covered this year has increased since last year but remains relatively low compared to many of the years that this ASU has been published for. However, there is a good breadth of elements covered, over 20 this year, with the most popular elements still being As, Hg and Se whilst Ge and Tc both make their first appearances this year. Another item to note is the decreasing quality of the abstract for many of the papers, with detail on the methodology, key results with data included, conclusions and implications thereof missing. This is likely to lead to fewer researchers reading the article. [ABSTRACT FROM AUTHOR]

This review of 177 references covers developments in 'Atomic Spectrometry' published in the twelve months from December 2022 to November 2023 inclusive. It covers atomic emission, absorption, fluorescence and mass spectrometry, but excludes material on speciation and coupled techniques which is included in a separate review. It should be read in conjunction with the previous review1 and the other related reviews in the series.2–6 A critical approach to the selection of material has been adopted, with only novel developments in instrumentation, techniques and methodology being included. The integration of chip-based sample preparation and sample introduction devices has become more advanced, pointing the way to more highly automated methods for clinical analysis. Linked with miniaturisation this should also drive the development of field deployable devices. The analysis of nanoparticles and nanomaterials continues to be an important area of research given the topical concerns of these particles in the biosphere. The trend to nano-analysis is also reflected by developments in LA and LIBS analyses: e.g. spatially highly resolved bioimaging, analysis of nanoparticles or isotope ratios at extremely low concentrations and high precision. [ABSTRACT FROM AUTHOR]

A simple, low-cost and sensitive technique using infrared radiation for thermochemical vapor generation coupled with atomic spectrometry was developed for the determination of mercury species in biological matrices. Thermochemical vapor generation (TVG) of inorganic and methylmercury species can be achieved by heating samples of formic acid solubilized materials with and without the use of hydrogen peroxide, respectively, at temperatures of 165 to 285 °C. Power output from a 1000 W infrared lamp was regulated via temperature-controlled output measured with a thermocouple. A quartz tube was used to flow the sample through the TVG reactor. The impacts of formic acid and hydrogen peroxide concentration, temperature and carrier gas flow (N2) were evaluated in the system on response from inorganic and methylmercury in order to identify optimal conditions for thermochemical vapor generation efficiency. The accuracy of the method was validated using Certified Reference Materials NIST 1641d and NRC DORM-1 and DOLT-3. [ABSTRACT FROM AUTHOR]

This is the 15th Atomic Spectrometry Update (ASU) to focus on advances in elemental speciation and covers a period of approximately 12 months from January 2022. This ASU review deals with all aspects of the analytical atomic spectrometry speciation methods developed for: the determination of oxidation states; organometallic compounds; coordination compounds; metal and heteroatom-containing biomolecules, including metalloproteins, proteins, peptides and amino acids; and the use of metal-tagging to facilitate detection via atomic spectrometry. As with all ASU reviews the focus of the research reviewed includes those methods that incorporate atomic spectrometry as the measurement technique. However, because speciation analysis is inherently focused on the relationship between the metal(loid) atom and the organic moiety it is bound to, or incorporated within, atomic spectrometry alone cannot be the sole analytical approach of interest. For this reason molecular detection techniques are also included where they have provided a complementary approach to speciation analysis. This year the number of publications covered has fallen again along with the number of elements covered, most likely due to effects of the Covid-19 pandemic restricting laboratory access. The most popular elements remain as As, Hg and Se and the range of matrices under study is still broad with biological, environmental and foods being the most popular. [ABSTRACT FROM AUTHOR]

This review of 200 references covers developments in 'Atomic Spectrometry' published in the twelve months from December 2021 to November 2022 inclusive. It covers atomic emission, absorption, fluorescence and mass spectrometry, but excludes material on speciation and coupled techniques which is included in a separate review. It should be read in conjunction with the previous review1 and the other related reviews in the series.1–6 A critical approach to the selection of material has been adopted, with only novel developments in instrumentation, techniques and methodology being included. After several years of consolidation of research in the area of elemental tagging, with very similar variations on the same themes being published, this has now evolved to include detection at the cellular level. This is largely a result of advances in single particle-ICP-MS and LA-ICP-MS mapping, coupled with multiple tagging approaches. These combined methods are very useful for diagnostics and imaging and perhaps show the way forward for this type of analysis. A more comprehensive assessment of the range of factors affecting the accuracy of isotope ratio determinations of non-radiogenic isotopes has been in evidence. Where corrections could not be made, some studies specified a range of concentration or molarity in which results remained within tolerance. In the future, this type of assessment should lead to more robust uncertainty estimates and potentially reduce the possibility of samples with erroneous deviations in their stable isotopes measurements. [ABSTRACT FROM AUTHOR]

This update covers publications from the second half of 2021 to the middle of 2022. Advances in the application of atomic spectrometry techniques to clinical and biological materials, foods and beverages are reviewed in the text, highlighting their key features. Technical details of sample collection and preparation, as well as progresses with analytical techniques are considered and three tables complement the text, summarising details of a larger spectrum of publications. During this period, the trend toward the application of multi-element techniques, such as EDXRFS, ICP-MS and LIBS continued, in particular for food authenticity studies. Triple quadrupole ICP-MS is becoming increasing popular, as it is less affected by interferences, as well as LIBS and XRF, that require minimal sample preparation. However, AAS is still considered a valid alternative for single or a limited number of elements: as in previous years, numerous pre-concentration techniques were presented, some of which explored "greener" reagents. The interest in NPs continued, both as a potential exposure risk and for their application as tags of biological materials, and led to a wider application of spICP-MS. Chromium speciation in food received more attention than usual during this period, providing evidence that the carcinogenic species CrVI was not present. A number of studies covered the application of atomic spectrometry techniques for the indirect determination of biological macromolecules, including an interesting application of LIBS for the rapid detection of the immune response to SARS-CoV-2. [ABSTRACT FROM AUTHOR]

Speciation analysis of heavy metals in suspended particulate matter (SPM) in water helps evaluate health risks, understand pollution status, trace pollution sources, and select a remediation approach. In this study, electrochemical mass spectrometry (EC-MS), which combines extraction, reaction and electrolysis with in situ electrospray ionization mass spectrometry (ESI-MS), is established to directly analyze heavy metal speciations in SPM. The samples were first collected in a homemade electrolytic cell by filtration, followed by sequential extraction. Water and methanol were first used to extract water-soluble and organic metal speciations, respectively. EDTA-2Na was used to react with the insoluble metal to form a soluble EDTA-metal chelate. For elemental speciation, electrolysis was used to convert them into metal ions. The extracted speciations were online and transferred to ESI for ionization. Four kinds of speciations, including water-soluble, organic, insoluble, and elemental could be detected in 1 hour with high sensitivity. A proof-of-concept application was carried out to sequentially analyze metal speciation in the SPM in a lake. The experimental results indicated that the SPM from the lake water contained Zn, Cu, Mn, Pb, and Fe in a water-soluble state, Pb, Zn, Cu, and Ni were in an insoluble state, and no heavy metals in organic and elemental states were found. Compared with the traditional methods, this method featured no complex matrix separation process, less sample consumption, and high analysis throughput, offering unique possibilities for advanced applications in environmental monitoring and risk assessment. [ABSTRACT FROM AUTHOR]

This is the 14th Atomic Spectrometry Update (ASU) to focus on advances in elemental speciation and covers a period of approximately 12 months from December 2020. This ASU deals with all aspects of the analytical atomic spectrometry speciation methods developed for: the determination of oxidation states; organometallic compounds; coordination compounds; metal and heteroatom-containing biomolecules, including metalloproteins, proteins, peptides and amino acids; and the use of metal-tagging to facilitate detection via atomic spectrometry. As with all ASUs, the focus of the research reviewed includes those methods that incorporate atomic spectrometry as the measurement technique. However, because speciation analysis is inherently focused on the relationship between the metal(loid) atom and the organic moiety it is bound to, or incorporated within, atomic spectrometry alone cannot be the sole analytical approach of interest. For this reason, molecular detection techniques are also included where they have provided a complementary approach to speciation analysis. This year, the number of publications covered has fallen, quite possibly due to the SARS-CoV-2 pandemic restricting laboratory access, but the number of elements covered remains high at over 30. The most popular elements are still As, Hg and Se, whilst more workers are using some form of separation to reduce the dissolved ion signal when undertaking analysis for NPs. There has also been an increase in the number of papers reporting on field deployable miniaturised devices for elemental speciation, a trend which will surely continue as the associated technologies develop more robust and less power hungry portable excitation sources. [ABSTRACT FROM AUTHOR]

This work focuses on providing fast and reliable separations of arsenobetaine (AsB), trimethylarsine oxide (TMAO), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), arsenocholine (AsC), arsenite (As(III)), and arsenate (As(V)). Two different methods are presented: (1) a one-column method for the determination of AsB, DMA, MMA, AsC, As(III), and As(V) with a separation time of ∼2 minutes and (2) a two-column method for the determination of AsB, TMAO, DMA, MMA, AsC, As(III), and As(V) with a separation time of ∼4.5 minutes. Recovery of the two methods falls between 94 and 107%. Methods were evaluated for accuracy by analyzing proficiency samples from Centre de Toxicologie du Québec (CTQ) and New York Department of Health (NYDOH). Correlation between the measured values and reference values was very good, with a <4.5% difference in results. Limits of detection in a urine matrix ranged from 2.8–6.0 ng L−1 As and 4.1–9.1 ng L−1 As for the one- and two-column methods, respectively. [ABSTRACT FROM AUTHOR]

This review of 194 references covers developments in 'Atomic Spectrometry' published in the twelve months from November 2020 to November 2021 inclusive. It covers atomic emission, absorption, fluorescence and mass spectrometry, but excludes material on speciation and coupled techniques which is included in a separate review. It should be read in conjunction with the previous review 1 and the other related reviews in the series. 2–6 A critical approach to the selection of material has been adopted, with only novel developments in instrumentation, techniques and methodology being included. [ABSTRACT FROM AUTHOR]

This is the 13th Atomic Spectrometry Update (ASU) to focus on advances in elemental speciation and covers a period of approximately 12 months from December 2019. This ASU review deals with all aspects of the analytical atomic spectrometry speciation methods developed for: the determination of oxidation states, organometallic compounds, coordination compounds, metal and heteroatom-containing biomolecules, including metalloproteins, proteins, peptides and amino acids, and the use of metal-tagging to facilitate detection via atomic spectrometry. As with all ASU reviews, the focus of the research reviewed includes those methods that incorporate atomic spectrometry as the measurement technique. However, because speciation analysis is inherently focused on the relationship between the metal(loid) atom and the organic moiety it is bound to, or incorporated within, atomic spectrometry alone cannot be the sole analytical approach of interest. For this reason, molecular detection techniques are also included where they have provided a complementary approach to speciation analysis. This year the number of publications concerning As speciation remains similar to those covered last year, as do those for studies on Se speciation. The recent growth in work concerning Hg speciation has halted, although this is still a popular topic with the number of reports concerning Fe, halogen and sulfur speciation also rising. The number of elements covered this year reaches 30, showing the breadth of the elemental speciation field and how such work is now becoming more routine. [ABSTRACT FROM AUTHOR]

A novel sulfur-containing functional core–shell magnetic porous organic polymer (Fe3O4@BD-TpMA-S-SH MOP) was synthesized as a magnetic solid-phase extraction (MSPE) sorbent for mercury speciation followed by high-performance liquid chromatography (HPLC)-inductively coupled plasma mass spectrometry (ICP-MS) detection. The prepared Fe3O4@BD-TpMA-S-SH MOP possessed rich active adsorption sites (S: 25 wt%), high magnetism (39.2 emu g−1) and high adsorption capacity (636, 656, 649 and 366 mg g−1 for Hg2+, methylmercury (MeHg+), ethylmercury (EtHg+) and phenylmercury (PhHg+), respectively). Under the optimal conditions, the limit of detection (LOD) of the developed MSPE-HPLC-ICP-MS method was 0.43, 0.55, 0.69 and 1.1 ng L−1 for Hg2+, MeHg+, EtHg+ and PhHg+, respectively, with a high enrichment factor (EF) in the range of 346–383-fold. The accuracy of the method was validated, and it was successfully applied for trace/ultratrace mercury speciation in environmental water and fish samples. The developed method has high sensitivity, low LOD, high EF, fast adsorption/desorption dynamics and good matrix resistance ability, showing great applicability in real sample analysis with complex sample matrices. [ABSTRACT FROM AUTHOR]

In this study, a method based on liquid chromatography and dynamic reaction cell inductively coupled plasma mass spectrometry (DRC ICP-MS) for the simultaneous speciation of arsenic [As(III), As(V), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenobetaine (AsB)] and mercury [inorganic mercury [Hg(II)] and methyl mercury (MeHg)] in fish was developed. The separation was complete in less than 4.5 min with a ZORBAX SB-Aq C18 column in combination with 5 mmol L−1 1-octanesulfonate, 5 mmol L−1 acetate buffer and 1% (v/v) isopropyl alcohol (IPA) at pH 4.0 as mobile phase A and 2 mmol L−1 L -cysteine in 1% (v/v) IPA (pH 4) as mobile phase B. With O2 as a reactive gas in the DRC sensitivity of both arsenic and mercury was improved due to the measurement of the former as 75As16O+ at m/z 91 and collision damping for both. The detection limits were in the range 0.005–0.007 ng As mL−1 and 0.013–0.015 ng Hg mL−1. To determine the accuracy, a certified reference material (NRCC DORM-3 fish protein) was analyzed where the sum of the concentrations of individual species agreed with total certified concentrations of As and Hg. The developed method was applied on a variety of fish samples. The As and Hg species in fish were quantitatively extracted, into a solution of 1% (v/v) HCl and 0.1% (m/v) Protease XIV taken in a closed centrifuge tube and kept in a pool of water which was heated to 70 °C for 60 min in microwaves. The spike recovery of individual arsenic and mercury species was between 97% and 103%. The precision between sample replicates was better than 7% with the HPLC-DRC-ICP-MS method. [ABSTRACT FROM AUTHOR]

Synthetic solutions of Rh and Pt at near neutral pH, as well as spiked natural waters are subjected to an ageing effect, which means that over time the speciation of the PGEs will be changed from their original composition due to aquation and hydrolysis, forming various hydroxy and aqua complexes. Due to slow ligand exchange reactions equilibrium speciation may not be rapidly attained. Ageing may affect the reactivity of the PGE solutions towards chelating resins used in the analysis of PGEs by Diffusive Gradients in Thin films (DGT). The aim of the study was therefore to investigate the performance of the chelating resins (Purolite S914 and S920 with thiourea and isothiourea functional groups, and IONQUEST® MPX-317 with a phosphine oxide thiourea functional group) for their applicability as a binding resin for DGT applications for Pt and Rh in natural waters using 17-day aged spiked solutions. Uptake kinetics experiments revealed that the direct uptake of Pt on the resins from aged solutions was fast and quantitative, whereas only 30% of Rh was directly bound on the resin. Likewise, much lower apparent diffusion coefficients were obtained for Rh in aged spiked river water (70% decrease) which can be explained by the formation of Rh(OH)3(s) which is not taken up by the resin gel. The addition of dissolved organic matter results in an increased solubilisation of Rh(OH)3(s) and an increased DGT labile fraction. The formation of Rh(OH)3(s) is less pronounced in seawater. For Pt, no species are formed which are not DGT labile. Thus, DGT accurately measures labile metal species in solution, discriminating labile from inert metal species. [ABSTRACT FROM AUTHOR]

Stannous fluoride (SnF2) is an effective antimicrobial agent and fluoride carrier to dental enamel. However, stannous complexes are known to readily oxidize in presence of O2 and interact with a variety of ligands such as organic and inorganic compounds commonly present in toothpaste. Therefore, the stability of stannous species inside toothpaste remains an open question. Here we probe the speciation of Sn in solutions of known composition and in commercial toothpaste using Sn K-edge X-ray absorption spectroscopy. We show that the oxidation state of Sn and its chemical nature depends on both paste composition and time of opening, with Sn ultimately oxidizing into amorphous Sn(IV) hydroxide, Sn(OH)4. These results highlight the effect of paste composition and utilization on the speciation of active ingredients such as SnF2, and contribute to a rational design of toothpaste formulations that enhances the stability of stannous agents. [ABSTRACT FROM AUTHOR]

In this study a procedure based on liquid chromatography (LC) and dynamic reaction cell inductively coupled plasma mass spectrometry (DRC ICP-MS), coupled with ultrasonic nebulization, for chromium speciation in rice was reported. Chromium (Cr) containing species, including Cr(III) and Cr(VI), were well separated by reversed phase HPLC with a C18 column as the stationary phase and a solution containing 0.5 mmol L−1 tetrabutyl ammonium phosphate (TBAP), 0.1 mmol L−1 EDTA and 2% (v/v) methanol (pH 6.9) as the mobile phase using isocratic elution. The chromatographic separation was complete in 4.5 min. Ammonia gas was employed as the reactive gas in the DRC to minimize spectral interference due to 40Ar12C+ and 35Cl16OH+ and 40Ar13C+ and 35Cl18O+ ions on the signal of 52Cr+ and 53Cr+, respectively. The detection limits were in the range 0.011–0.012 ng Cr mL−1. To verify the accuracy, the developed procedure was applied on a certified reference material (NIST SRM 1573a Tomato Leaves) wherein the sum of the concentrations of individual species agreed with the total certified concentration of Cr. Species were extracted using microwave heating with 1% (v/v) HF and 2 mmol L−1 EDTA. After ensuring the accuracy, this procedure has been applied to determine various Cr compounds present in rice and rice cereal. Supernatants were injected directly into the LC-ICP-MS system after dilution. The spike recovery was in the range of 95–105% and precision between sample replicates was better than 5% for all determinations. The LC-ICP-MS results showed satisfactory agreement with the total Cr concentrations obtained by ICP-MS analysis. Both Cr(III) and Cr(VI) were present in the samples analyzed. An unknown Cr compound was found in all the rice samples analyzed. [ABSTRACT FROM AUTHOR]

The measurements of X-ray emission lines in atomic decay to the L-shell of thallium compounds were performed using a laboratory source-based conventional wavelength dispersive spectrometer. A large set of physical fundamental parameters such as X-ray transition energies, natural linewidths and relative transition probabilities were determined by robust spectral fitting trials. The current effort presents valuable intuition about the chemical effect in distinct thallium compounds, viz., pure Tl, TlX [X = (NO3)3, I, and Cl], and Tl2X (X = O3 and SO4) on the Lp (p = l, α, η, β) X-ray lines. The investigation of chemical effects is one of the highly pressing tasks in understanding the various physical fundamental parameters in distinct metal-compounds. The results illustrate that the Lp (p = l, α, η, β) X-ray lines emitted from various thallium targets show energy shifts of ∼0.03–3.39 eV relative to the pure thallium target. In general, the outcomes of this study are consistent with the published data associated with the framework of the atomic Hartree–Fock (AHF), relativistic many-body problems in atoms and semi-empirical procedure developed within intermediate coupling calculations. For the first time, several physical fundamental parameters of thallium compounds have been investigated in this work, which are likely due to the adoption of robust spectral fitting procedures. The abruptly deviating peak profile variations found in distinct thallium-based metal-compounds can be reflected in the viewpoint of the linewidth, different electronegativity values of adjacent ligands, effective charge, changes in the transition probability, mixed oxidation states of thallium and valence to core exchange interactions. Furthermore, in the current study, the possible connection among X-ray line shifts and parameters are systematically scrutinised. [ABSTRACT FROM AUTHOR]

The Li4Ti5O12 (LTO) compound has been investigated as an alternative negative electrode material for lithium ion batteries (LIBs), which are being used as energy storage devices in stationary systems as well as for electric vehicles due to their many interesting features. The LTO compound has shown remarkable Li-ion intercalation/de-intercalation reversibility, demonstrating also zero-strain volume change during the cycling process along with notable safety performance. Furthermore, LTO has a high voltage plateau in comparison with other negative material candidates, helping to avoid the deposition of metallic lithium in the dendrite form. Due to its performance and potential application in LIBs, a deep knowledge regarding the behavior of this LTO compound is of high interest. In this work, energy-dispersive resonant inelastic X-ray scattering (EDIXS) is used to fulfill this need. In addition, XANES measurements were carried out as complementary methodology. The results indicate that EDIXS can differentiate LTO chemical compounds (lithiated and de-lithiated) with high sensitivity, and is a reliable tool to perform chemical speciation analysis on such samples. In addition, the results confirm theoretical predictions regarding the composition of different oxidation states of titanium associated with different states of charge/lithiation of the LTO-spinel also. The proposed methodology can be easily applied to other lithium-based materials and beyond them, such as those based on sodium and novel technologies based on polyvalent cations including magnesium and aluminium. [ABSTRACT FROM AUTHOR]

Silicon speciation in light petroleum products through the hyphenation of gas chromatography with ICP-tandem mass spectrometry (GC-ICP-MS/MS) is described in the present work. Eleven silicon compounds (nine siloxanes, trimethylsilanol and triethylsilane) have been taken as model molecules. The carrier and optional gas flow rates as well as the hydrogen gas flow rate in the octopole reaction cell (ORC) were critical variables. They precluded both the sensitivity and the extent of the effects caused by the sample matrix and silicon nature. The optimization of the latter variable mitigated the m/z 28 interference (14N14N+ and 12C16O+). Moreover, under the optimized conditions, a universal response was found irrespective of the silicon chemical form and sample matrix. The analytical performances of the method have been evaluated. Thus, the ICP-MS/MS response was linear between 0 and 500 μg kg−1 with correlation coefficients up to 0.999, whereas the limit of quantification (LOQ) ranged from 8 to 60 μg kg−1. Moreover, no drift was found for quality control samples analysed along a given analytical run. Only, the most volatile compound, i.e., trimethylsilanol (TMSOH), induced a drop in sensitivity caused by its partial evaporation from the GC vial. The method was validated by the analysis of real samples and the results were compared with those obtained by inductively coupled plasma optical emission spectrometry (ICP-OES) and X-ray fluorescence. No significant differences in Si total content provided by the three methods were found. These results demonstrated that all silicon species were taken into account using GC-ICP-MS/MS as the speciation method. Real light petroleum products, especially coker naphtha samples, were analyzed and it was verified that they only contained cyclic siloxanes (D3–D6), mainly hexamethylcyclotrisiloxane (D3) and octamethylcyclotetrasiloxane (D4). [ABSTRACT FROM AUTHOR]

The transport of arsenic from soil through to edible crop is important when assessing the potential health risks from a food source. Samples of soil, irrigation water and the rice plant, Oryza sativa, were collected from an agricultural site in the Middle East. Total As, its speciation and DNA fractionation were evaluated using HPLC-ICP-MS in samples which included the root, stem, leaf and grain of the rice plant. Methodology was validated through the use of CRMs. The highest concentration of As was found in the root of the plant and the lowest in the grain. The concentrations found for As were: soil (aqua-regia extractable; 2.88 μg g−1), irrigation water (0.58 μg L−1), roots (8.28 μg g−1), stem (4.00 μg g−1), leaves (2.93 μg g−1) and grain (1.02 μg g−1). Levels of inorganic AsV and AsIII were identified in the soil and plant material, while organo-arsenic species (DMA, MMA) were below the limit of detection. The 'plant available' levels of As in the soil (14%) were determined as part of a full, validated BCR three-step sequential extraction procedure. Since As can behave as a phosphate analogue, a method was developed for the extraction of vegetative DNA to determine the different forms of As associated with, or integrated within, the DNA fractions. Measurement of As in the DNA extracts were above the LOD (0.019 μg kg−1) for the root, stem and leaf samples. The concentration of both weakly and strongly associated As with DNA obtained from the root, stem and leaf decreased with decreasing total As concentrations. A narrow, near-constant ratio for the strongly associated As value (As/total As DNA) in all root, stem and leaf DNA samples (41.3 ± 0.3%) was further evidence for the incorporation of As into the DNA. [ABSTRACT FROM AUTHOR]

This is the 12th Atomic Spectrometry Update (ASU) to focus on advances in elemental speciation and covers a period of approximately 12 months from December 2018. This ASU review deals with all aspects of the analytical atomic spectrometry speciation methods developed for: the determination of oxidation states; organometallic compounds; coordination compounds; metal and heteroatom-containing biomolecules, including metalloproteins, proteins, peptides and amino acids; and the use of metal-tagging to facilitate detection via atomic spectrometry. As with all ASU reviews the focus of the research reviewed includes those methods that incorporate atomic spectrometry as the measurement technique. However, because speciation analysis is inherently focused on the relationship between the metal(loid) atom and the organic moiety it is bound to, or incorporated within, atomic spectrometry alone cannot be the sole analytical approach of interest. For this reason molecular detection techniques are also included where they have provided a complementary approach to speciation analysis. This year the number of publications concerning As speciation has fallen by about half, as have studies on Se speciation. Growth areas continue to be Hg and 'biomolecules', with the number of reports concerning halogen and sulfur speciation also rising. The number of elements covered this year is again over 20, showing the breadth of the elemental speciation field. [ABSTRACT FROM AUTHOR]

A novel and simple interface used in a high-performance liquid chromatography-catalytic cold vapor-atomic fluorescence spectrometry (HPLC-CCV-AFS) hyphenated system without post-column digestion, based on the catalytic degradation of organic mercury by directly introducing Fe3+ into the carrier, was developed for the speciation of mercury. The synergy of Fe3+ with L -cysteine or mercaptoethanol reduces the Fe3+ concentration. The parameters influencing mercury separation and determination were optimized, including the content of Fe3+ in the carrier, the concentration of L -cysteine, KBH4 and HCl, and the flow rate of the carrier gas and shielding gas. Under the optimized conditions, the limits of detection (LODs) for monomethylmercury (MeHg), ethylmercury (EtHg) and Hg2+ (IHg), based on a 100 μL sample, were 0.06, 0.09, and 0.13 μg L−1, while the LODs of MeHg, EtHg and IHg in food samples, based on 0.2 g sample and 50 mL final sample volume, were 15, 23 and 33 μg kg−1, respectively. The proposed method with a simple interface, high sensitivity, low instrument and operation cost, easy operation, reduced damage to the instrument pipeline and reduced use of harmful and organic reagents was successfully applied to fish samples and is suitable for routine use. [ABSTRACT FROM AUTHOR]

Synchrotron hard X-ray spectroscopy with focussing optics allows recording X-ray fluorescence (XRF) maps at energies around element specific X-ray absorption edges. Stacking multiple XRF maps along the energy axis yields chemical images that contain spatially resolved information on the speciation of the absorber in the sample matrix at the micrometre scale. Short dwell times needed to keep measurement time and radiation-induced sample changes within acceptable limits result in spectral noise that affects the uncertainty in data analysis. In this study, we develop a model to quantify the uncertainty associated with the processing of XRF image stacks using Bayesian inference. To demonstrate the potential of our approach, the model is applied to stacks of XRF maps collected around the copper (Cu) K-edge (pixel size: 3 × 3 μm2, map sizes: 500 × 500 μm2). The investigated samples include digested sewage sludge spiked with either CuO nanoparticles (NP) or dissolved CuSO4 and their corresponding ashes obtained through incineration. The chemical imaging data reveal differences in species distribution between sludge spiked with CuO NP or dissolved Cu. These differences disappear during the incineration process and the resulting ashes exhibit almost identical Cu species distribution. The uncertainty analysis approach developed in this study can be used for data interpretation, but can also be used for the planning of chemical imaging experiments at synchrotron beamlines. [ABSTRACT FROM AUTHOR]

Brown seaweed such as Laminaria digitata is known to accumulate arsenic at a concentration of more than 100 mg kg−1. How the algae can tolerate such a high level of arsenic has traditionally been studied by arsenic speciation analysis using HPLC-ICPMS, but the knowledge of its molecular forms has not yet given any answers. Here we demonstrate for the first time that the combination of speciation analysis with high resolution imaging by NanoSIMS and TEM identifies not only the molecular structures of arsenic but also the location of arsenic in cells and cell substructures in a brown seaweed species. The majority of 117 mg kg−1 arsenic in L. digitata fronds was in the form of inorganic arsenic (53%) and arsenosugars (32%) and only 1.5% of total arsenic as arsenolipids (mainly as AsHC and AsPL). A lateral resolution of 300 nm and the concentration of arsenic were high enough for the localization of arsenic in the cells of the seaweed using NanoSIMS. The majority of arsenic was found in the cell walls and cell membrane, while the inside of the cell was almost arsenic free, which is not expected if the majority of arsenic species are hydrophilic. The NanoSIMS images question the integrity of the arsenic species during extraction for the speciation analysis and indicate that inorganic arsenic is unlikely to occur freely in the seaweed. Whether inorganic arsenic and the arsenosugars are bound directly to the polymeric carbohydrate alginates or fucoidans in the seaweed is unclear and needs further investigation. [ABSTRACT FROM AUTHOR]

A micro-solid phase extraction procedure based on the use of freshly prepared magnetic ferrite particles allows small amounts of silver in solution to be preconcentrated. Phase separation is carried out using a magnet. For a typical 10 mL water sample at a pH close to 8, the solid recovered phase (about 2 mg) is dissolved in 0.1 mL of a solution containing 8% v/v concentrated hydrofluoric acid and 4% v/v concentrated nitric acid and then introduced into an electrothermal atomizer to obtain the silver atomic absorption signal. The detection limit is 3 ng L−1 and the relative standard deviation for five measurements at the 50 ng L−1 silver level is 5.7%. Only silver(I) is retained. By repeating the procedure with another aliquot of sample after a suitable oxidation process, the discrimination between solid and dissolved silver can be achieved. The results are verified by analyzing reference water samples with a certified silver content. In addition to the application to water analysis, data for silver in items of clothing, sticking plasters and vegetables are given. The procedure is suitable for potable waters but not for seawater due to the interference caused by the high chloride concentration. [ABSTRACT FROM AUTHOR]

A von Hamos geometry based wavelength dispersive spectrometer combined with an in situ reactor cell has been developed to measure non-resonant sulfur Kα emission for the in situ speciation of low concentrations of sulfur. The spectrometer operates at 15 cm focusing radius, is equipped with a curved Si(111) crystal and a position sensitive detector, and is capable of achieving an energy resolution of 0.56 eV at 2.3 keV. We present the details of the spectrometer and dedicated sample-cell design to study chemical reactions in situ. The spectrometer capabilities are exemplified by an in situ study of sulfur speciation during H2S poisoning of SiO2 supported Ru nanoparticles performing CO methanation. [ABSTRACT FROM AUTHOR]

This is the 11th Atomic Spectrometry Update (ASU) to focus on advances in elemental speciation and covers a period of approximately 12 months from December 2017. This ASU review deals with all aspects of the analytical atomic spectrometry speciation methods developed for: the determination of oxidation states; organometallic compounds; coordination compounds; metal and heteroatom-containing biomolecules, including metalloproteins, proteins, peptides and amino acids; and the use of metal-tagging to facilitate detection via atomic spectrometry. The review does not cover fractionation, which is sometimes termed operationally defined speciation. As with all ASU reviews the focus of the research reviewed includes those methods that incorporate atomic spectrometry as the measurement technique. However, because speciation analysis is inherently focused on the relationship between the metal(loid) atom and the organic moiety it is bound to or incorporated within, atomic spectrometry alone cannot be the sole analytical approach of interest. Therefore, molecular detection techniques are also included where they have provided a complementary approach to speciation analysis. As in previous years, As speciation continues to dominate the current literature with a significant number of publications concerning Hg and Se speciation and 'biomolecules', in which category a number of papers covered in the Se section could also belong. The number of elements covered in these updates also continues to rise with the speciation analysis of over 20 elements reported this year. [ABSTRACT FROM AUTHOR]

Measuring chromium species in drinking water has become of particular interest due to daily environmental contamination that is caused by industrial processes. Agencies such as the US Environmental Protection Agency and the European Union continue to investigate the maximum to which Cr(vi) contaminant levels should be set; thus laboratories must seek more efficient ways of performing routine analyses. In this work a single platform, automated speciation and total metals method is presented for chromium speciation in drinking water, waste water, industrial waters, and recipient waters, and for total metals in sludges, soils, organic waste, ashes, biological samples, or paint. Samples were measured using a prepFAST IC system for Cr(iii) and Cr(vi) and the results were compared to the HPLC results. In addition, samples from the aqua regia total method were compared to those of the total metals method performed using the prepFAST IC. Sample comparisons resulted in linear regression plots with very good correlations, greater than 0.97 for total metals over a dynamic range of 0.010–100 000 μg L−1 for 63 elements and greater than 0.98 for Cr(vi) speciation. The limits of detection for Cr(vi) and Cr(iii) using the prepFAST IC and ICP-MS combination are 7 ng L−1 and 12 ng L−1, respectively. The new method resulted in an ∼43× improvement in detection limits as compared to the previous method employed in our laboratory. The accurate results for quality control samples of Cr(vi) were in good agreement with the historical values collected using the old method. [ABSTRACT FROM AUTHOR]

The accurate, stable and fast analysis of mercury species, such as Hg2+, MetHg and EtHg, in complicated aquatic animal matrices is an ongoing challenge. Herein, an efficient analytical method for Hg species was developed using a QuEChERS-like approach (QuEChERS is a sample preparation method for pesticide residue determination based on dispersive solid phase extraction which is quick, easy, cheap, effective, rugged and safe) followed by liquid chromatograph atomic fluorescence spectrometry (LC-AFS). For the first time, a novel concentric tube extraction cell consisting of an outer tube (o-tube), an inner tube (i-tube), a cap for the o-tube and a stopper for the i-tube with a series of PVDF membranes was designed as an integrated tool for extracting and purifying Hg species, where the membrane acts as a “valve” driven by centrifugal force vs. the membrane surface tension force. Here, the newly designed QuEChERS automated sample preparation system was used for shaking and centrifugation of the test samples. Aquatic animal samples were extracted with 10% HCl + 1% thiourea + 0.15% KCl solution in the o-tube by shaking at 800 rpm for 12 min; then, under the force arising from centrifugation at 4000 rpm for 5 min, the analyte solution containing Hg species penetrated the membrane into the i-tube; after shaking at 600 rpm for 3 min and centrifuging at 4000 rpm for 2 min, 0.5 mL chloroform pre-added to the i-tube separated the proteins and lipids from Hg species; finally, the upper layer extract in the i-tube was studied by LC-AFS. Under the optimum conditions, from 5 μg L−1 to 1000 μg L−1, the linear regression coefficient (R2) was ＞0.998; the spiked recoveries of Hg2+, MetHg and EtHg in aquatic animal samples were in the 88% to 104% range, and the method could achieve desirable limits of detection below 3 μg kg−1 (sample mass = 2 g). The relative standard deviations (RSD) were ＜10% for 10 μg kg−1 standards and real samples, including fish, lobster, scallop and carp; this precision was found to be acceptable. The whole sample pre-treatment duration can be controlled within 25 min, namely an average of ∼2 min per sample considering 12-sample throughput of the automated sample preparation system. The proposed QuEChERS-like LC-AFS method is suitable for Hg2+, MetHg and EtHg determination in aquatic animal samples, with advantages of simplicity, quickness, accuracy, high sensitivity and minimum personal error, to protect public health against mercury hazards. [ABSTRACT FROM AUTHOR]

Vanadium (V) exists in a number of oxidation states in the environment, potentially making it a useful chemical tracer of both modern and ancient redox conditions in Earth's oceans. However, the use of V as a redox tracer relies on a comprehensive understanding of V geochemistry in marine systems, which in turn requires the ability to accurately measure its solid-phase speciation in marine sediments. Here we report the first evaluation of both bulk and microfocused synchrotron X-ray spectroscopy to investigate the speciation of V in a modern coastal marine sediment. Semi-quantitative spectral analysis of pre-edge peak areas, extracted from bulk X-ray absorption near edge structure (XANES) spectra, determined the average oxidation state of V in the sediment samples to be ∼3.5, indicating a mixture of V(iii) and V(iv). Signal-to-noise ratios of XANES spectra were not sufficiently high to allow accurate quantitative analysis by commonly used linear combination fitting approaches. We also demonstrate that high-resolution element mapping by scanning X-ray fluorescence microscopy (SXFM) provides useful complementary geochemical information for resolving possible V host phases in sediments, but is limited in its ability to distinguish V and Ti due to the proximity of their fluorescence emission lines. This study highlights the practical limitations and opportunities of X-ray spectroscopy for investigating V speciation in marine sediments, and reinforces the importance of comprehensively evaluating X-ray spectroscopic techniques prior to applying them to investigating new elements or sample types. [ABSTRACT FROM AUTHOR]

Flay ash, cement and electric arc furnace (EAF) dust are frequently mixed in building composites. From them, chromium (Cr), arsenic (As), molybdenum (Mo) and vanadium (V) may be leached. Concentrations of V in leachates may be significantly higher than those of Cr, As and Mo, making simultaneous speciation analysis particularly difficult. In this work, a high performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS) procedure was used for simultaneous speciation of chromate, arsenate, molybdate and vanadate. First, the behaviour of Cr, As, Mo and V species in different oxidation states was studied during their separation under acidic (pH 5) and alkaline (pH 12) conditions. At alkaline pHs chromate, arsenate, molybdate and vanadate were simultaneously separated and eluted at retention times from 390 to 450 s, 230 to 270 s, 340 to 430 s and 270 to 380 s, respectively and detected on-line by ICP-MS, recording m/z 52, 75, 95 and 51, respectively. When V species were leached in significantly higher concentrations than Cr, Mo and As, their detection was possible at the low abundance (0.25%) 50V isotope, which is also the mass of the 50Cr isotope (abundance 4.345%), due to selective separation between V and Cr species. Good repeatability of measurement (RSD better than ±3.0%) and quantitative elution of elemental species (column recoveries 99–105%) were obtained. Finally, the procedure was applied in the simultaneous speciation analysis of chromate, arsenate, molybdate and vanadate in highly alkaline aqueous leachates from composites consisting of fly ash, cement and EAF dust that contained a wide range of concentrations of vanadate. [ABSTRACT FROM AUTHOR]

In this work, a novel analytical approach for the speciation of inorganic As (iAs) and inorganic Sb (iSb) by total reflection X-ray fluorescence based on the selective generation of arsine and stibine followed by trapping onto quartz reflectors containing immobilized palladium nanoparticles (Pd NPs) is developed. Pd NPs were synthesized by chemical reduction under mild conditions (i.e., a water : ethanol mixture was used as the reducing agent) and immobilized onto quartz substrates following the silanization strategy with 3-mercaptopropyltrimethoxysilane. For microextraction and preconcentration of iAs and iSb, volatile hydrides generated in a continuous flow system were flushed onto the immobilized Pd NPs for catalytic decomposition at ambient temperature. A 26−2III factorial fractional design was used for screening the effect of the variables involved in the hydride generation and preconcentration steps. Selective trapping of As(iii) and Sb(iii) was accomplished following arsine and stibine generation under different reaction conditions, i.e., selective determination of As(iii) in citric acid/citrate buffer medium (pH 4.5) and selective determination of Sb(iii) in a highly acidic medium (pH ＜ 2). In addition, As(v) and Sb(v) were pre-reduced to As(iii) and Sb(iii) with a KI–ascorbic acid mixture for simultaneous determination of total iAs and total iSb. The As(v) and Sb(v) contents were estimated by the difference between both measurements. Limits of detection (LODs) of 0.09, 0.10, 0.50 and 0.80 μg L−1 for As(iii), As(v), Sb(iii) and Sb(v) were obtained, respectively. Overall efficiencies of 75% for iAs and 80% for iSb were obtained. Speciation analysis of iAs and iSb in natural waters at the sub-ppb level is demonstrated. [ABSTRACT FROM AUTHOR]

Arsenic speciation in seafood after several culinary treatments was performed and AsB, As(iii), DMA, MMA and As(v) species were determined by liquid chromatography hyphenated to triple-quadrupole inductively coupled plasma mass spectrometry (LC-ICP-MS/MS) using O2 as the reaction gas for the conversion of 75As to 75As16O. The influence of culinary treatments (boiling, frying and sautéing) with or without the addition of spices (salt, lemon juice and garlic) on the As species in blacktip shark and Asian tiger shrimp was investigated. Arsenic species were extracted by using a 30 mmol L−1 HNO3 solution. Ammonium phosphate (10 mmol L−1) was used as the mobile phase. The influence of pH and the addition of 1% (v/v) methanol were investigated. Oil, water, butter and the spices used during cooking were analysed to perform a close mass balance of the total As. The speciation method was also employed for a certified reference material (CRM, DORM-3), and the accuracy was evaluated by statistical comparison between the certified value and the total As concentration determined by ICP-MS after acid digestion and also by a comparison of the sum of As species with the total As. It was demonstrated that the culinary treatments practically did not influence the stability of As species in uncooked seafood. On the other hand, significant analyte losses (from 15 up to 45%) were observed for boiled seafood. The speciation analysis method presented accuracy and robustness for both raw seafood and seafood after the culinary treatments. The limits of quantification were 4, 21, 4, 9 and 18 ng g−1 for AsB, As(iii), DMA, MMA and As(v), respectively. This study allowed the determination of As species in seafood after culinary treatments, thus offering additional information about the behaviour of species during cooking. [ABSTRACT FROM AUTHOR]

Total antimony and its +V and +III oxidation state species were determined in twelve spirit samples (Greek raki and tsipouro) stored in polyethylene terephthalate bottles. Reliable and reproducible results were obtained following direct analysis by using ICP-MS providing total Sb concentrations between 0.4–4 μg L−1. Antimony speciation analysis by LC-ICP-MS was also assessed, showing the presence of both inorganic Sb species along with an unknown Sb complex, which was the predominant species in all samples analysed. The structure of this complex was investigated by using liquid chromatography with high-resolution tandem mass spectrometry. The analysis gave evidence for an acetaldehyde–bisulphite pyruvate Sb complex with the formula: C7H14O12S2Sb. The proposed ligands are organic substances expected to be present in the raki matrix. In addition, the influence of high temperature storage conditions and extended exposure times up to two weeks, on Sb migration from PET bottles into raki samples was investigated. Total Sb and Sb species content was determined by ICP-MS and LC-ICP-MS, respectively. The concentrations determined were in the range of 5.6 to 28 μg Sb per L spirit after a week of storage at 60 °C. In which case, inorganic Sb(v) and Sb(iii) became the predominant species in comparison to the “novel” organic Sb complex. [ABSTRACT FROM AUTHOR]

An on-line UV-induced vapor generation method has been developed that allows simultaneous conversion of selenocyanate [SeCN−] and [Se(iv)] to volatile species for their subsequent determination by IC-ICPMS in petroleum refinery wastewater with improved detection limits. The species present in the sample were separated on an anion-exchange column using a step gradient with NaOH as the eluent, and were subsequently converted to their volatile forms by UV irradiation in the presence of a mixture of HCOOH–HNO3 followed by quantitative determination using an ICP-MS. Employing a 200 μL sample injection loop, the species separation was achieved within 7 min and with the best detection limits achieved at 0.01 μg L−1 and 0.06 μg L−1 for SeCN− and Se(iv) respectively while the reproducibilities achieved for retention times and peak areas in the chromatograms were better than 1.3% and 5.0% respectively. The method was successfully employed to study the quantitative speciation of selenium in three petroleum refinery wastewaters with accuracy of the results obtained validated by two independent methods. Further validation was carried out by a standard addition method and also by analysing a certified reference material BCR-713, wastewater effluent. Quantitative recoveries (＞95%) were observed for both Se(iv) and SeCN− in refinery wastewater. [ABSTRACT FROM AUTHOR]

Based on a novel green dielectric barrier discharge plasma induced chemical vapor generation (DBD plasma-CVG), an on-line hyphenation of high performance liquid chromatography (HPLC) with atomic fluorescence spectrometry (AFS) was developed for the speciation of inorganic mercury (Hg2+), methylmercury (MeHg) and ethylmercury (EtHg). Without the use of other chemical reagents, the decomposition of organic mercury species and the reduction of Hg2+ could be completed in one step with the DBD plasma-CVG system. The operating parameters of DBD plasma-CVG and HPLC were optimized. Separation of mercury species was accomplished in less than 14 min on a ZORBAX SB-C18 separation column with a mobile phase containing 0.01% (v/v) 2-mercaptoethanol, 10% (v/v) methanol and 0.06 mol L−1 NH4Ac at pH 6.8. The limits of detection of the method were found to be 1.6, 0.42 and 0.75 μg L−1 for Hg2+, MeHg and EtHg, respectively. The developed method was validated by determination of the main analytical figures of merit and applied to the analysis of the certified reference material GBW10029 (tuna fish). The on-line interfacing of HPLC with DBD plasma-CVG-AFS for the speciation of mercury is simple, environmentally friendly, and represents an attractive alternative to the conventional tetrahydroborate interface system. [ABSTRACT FROM AUTHOR]

A downsized wavelength dispersive X-ray spectrometer, employing a flat crystal and a CCD detector for use with focused ion beams has been constructed and employed to study ion beam induced chemical effects in Si K X-ray spectra from silicon and its selected compounds. By using ADP, PET and LiF(110) diffraction crystals, the spectrometer can measure X-rays in the energy range between 1.2 and 8.4 keV, with the energy resolution E/ΔE(FWHM) = 1850 on Al Kα and 1580 on Si Kα achieved with 2 MeV protons. This energy resolution enables the study of secondary effects in the K X-ray spectra of light elements, L-shell spectra of medium Z elements and M-shell spectra from heavy elements. The K X-ray spectra of silicon and selected silicon compounds were measured after excitation with 2 MeV protons and 20 MeV carbon ions focused to micrometer size. The results obtained for peak relative intensities were analyzed to study their dependence on the silicon oxidation states and effective charge on Si. The results were compared with the existing data obtained by proton, electron and photon induced ionization mechanisms, and clear differences between the ionization sources were observed. Si Kα multiple ionization satellites were studied with 20 MeV carbon ions on Si, SiO2 and SiC. The variation of apparent average L vacancy fraction pLx with effective charge on Si was studied. It has been shown that, for ionization by 20 MeV carbon ions, the relative KαL2 intensity is more sensitive to the chemical environment compared to pLx values. [ABSTRACT FROM AUTHOR]

Fish otoliths (“ear stones”) are major environmental indicators used in ecology and fisheries sciences. Otoliths consist of a biomineral material containing an organically-templated mineral calcium carbonate, normally aragonite, in which strontium is incorporated at trace to minor levels depending on water chemistry and individual physiology. Sr content and fluctuations inform on the life histories of ancient specimens and provide data for palaeoenvironmental reconstructions. Identifying the impact of post-mortem alteration is a critical question to assure the reliability of such work. A central parameter for the reliability of Sr content as a palaeoenvironmental proxy is whether the mode of incorporation can be considered as stable and homogenous at the microscale in otoliths over thousands of years. In addition, it is important to know whether a different kind of speciation of Sr is observed, especially at the outer surface of the sample in contact with the soil and local environment. Here, a novel combination of synchrotron microscale point analyses and raster-scanning X-ray absorption spectroscopy is implemented and used for the first time to study otoliths at different length scales, spanning from millimetres down to micrometres. Strontium is found in substitution for calcium in aragonite in all our analyses of five Holocene otoliths and their three modern counterparts; the first set of samples from the Peruvian coast, up to 11 000 years old, are studied for their potential as palaeoenvironmental proxies. The chemical environment of strontium in otoliths is independent of content of this element, location in the otolith, species, and archaeological age. This is shown with a high lateral resolution (about 10 μm) over wide fields of view, as a way to consolidate macro-scale approaches. To our best knowledge, this work is the first report of the chemical environment of strontium in ancient otoliths. Our work opens the way to new approaches to validate palaeoenvironmental studies of biocarbonate paleoproxies. [ABSTRACT FROM AUTHOR]

In this study, an analytical methodology based on a combination of dispersive liquid–liquid microextraction with laser-induced breakdown spectrometry was evaluated for simultaneous pre-concentration, speciation and detection of Cr. The microextraction procedure was based on the injection of appropriated quantities of 1-undecanol and ethanol into a sample solution containing the complexes formed between Cr(vi) and diethyldithiocarbamate (DDTC). The main experimental factors affecting the complexation and the extraction of metal (pH, DDTC concentration, extractant and volume of disperser solvents) were optimized using a multivariate analysis consisting of two steps: a Plackett–Burman design followed by a Circumscribed Central Composite Design (CCCD). Under optimum microextraction conditions, the analytical figures of merit of the proposed methodology were assessed. The method was finally applied to the analysis of a certified reference material hard drinking water (ERM® CA011a), yielding results in good agreement with the certified value. [ABSTRACT FROM AUTHOR]

A new enrichment nanosorbent based on mesoporous silica functionalized with 1,5-bis(2-pyridyl) methylene thiocarbohydrazide was synthesized and characterized. From the study of its adsorption capacity toward metal ions, it was observed that Hg2+ is one of the elements with higher adsorption capacity on the nanosorbent, 173.1 μmol g−1 at pH 5. Thus, a flow injection solid phase extraction and cold vapor generation method for its determination and speciation based on the use of this new chelating nanosorbent was optimized. The method developed has been shown to be useful for the automatic pre-concentration and sequential determination of mercury and methylmercury in environmental and biological samples. The system was based on chelating retention of the analytes on a mini-column filled with the new nanosorbent and their sequential elution by using two different eluents, 0.2% HCl for CH3Hg+ and 0.1% thiourea in 0.5% HCl for Hg2+. The determination was performed using inductively coupled plasma mass spectrometry. Under the optimum conditions and 120 s preconcentration time, the enrichment factors were 4.7 and 11.0, the detection limits (3σ) were 0.002 and 0.004 μg L−1, the determination limits (10σ) were 0.011 and 0.024 μg L−1, and the precisions (calculated for 10 replicate determinations at a 2 μg L−1 standard of both species) were 2.8 and 2.6% (RSD); for CH3Hg+ and Hg2+, respectively. Linear calibration graphs were obtained for both species from the determination limits to at least 70 μg L−1. For the quality control of the analytical performance and the validation of the newly developed method, the analyses of two certified samples, LGC 6016 estuarine water and SRM 2976 mussel tissue, were performed. The results showed good agreement with the certified values. Also the method was successfully applied to the speciation of mercury in sea-water samples collected in the Málaga Bay. [ABSTRACT FROM AUTHOR]

Inorganic arsenic species in ambient particulate matter (PM10 and PM2.5) have been determined in an urban area, in the vicinity of a metallurgical industrial plant. The developed high performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC/ICP-MS) method allows monitoring of particulate As(iii) and As(v)-species, with a limit of quantification of 0.34 ng m−3 As(iii) and 0.23 ng m−3 As(v), respectively. Good agreement was obtained between the sum of the concentrations of As(iii) and As(v) determined by HPLC/ICP-MS and the total As concentrations determined by XRF, indicating a complete extraction of the As species. During the measuring campaigns for PM10 and PM2.5, a significant conversion (oxidation) up to 54% of exogenous spiked As(iii) was observed. The total amount of the spiked As(iii) was well-recovered (PM10 and PM2.5 on average 108% and 101%, respectively). The extraction of the filter in combination with the sampled air matrix is likely to induce the As(iii) conversion. The average measured As concentration in PM10 during a 40-day monitoring campaign (30 ng m−3) at a hot spot location is above the European target value of 6 ng m−3. The measured As concentration in PM2.5 was half the value of the measured concentration in PM10 and no relative enrichment of total As was observed in either particulate matter fractions. However, in PM10, As(v) was the main component, while in PM2.5, As(iii) was the dominant species. During the monitoring campaign, the fraction of particulate As(iii) varied between 19 and 61% in PM10 and a trend towards a higher fraction of As(iii) with increasing concentration of total As was observed. XANES and XRD analyses were used for the identification of arsenic species in local PM sources and confirmed the presence of Ca3Sr2(AsO4)2.5(PO4)0.5(OH), As2O3 and As2O5 species. [ABSTRACT FROM AUTHOR]

The importance of measuring arsenic (As) species has been appreciated for a long time mainly because of the wide spread knowledge of arsenic's toxicity and its use as a poison. Increasingly health, environmental and food regulations have been written around As species rather than total concentrations. Knowledge of As speciation is important as the chemical form of As controls its bioavailability, toxicity, mobility and therapeutic benefits. Arsenic is present as inorganic (arsenate, arsenite, thioarsenates), complexed (arsenic glutathionines and phytochelatins), low molecular weight (monomethylarsonate, dimethylarsenate, arsenobetaine, arsenocholine etc.) and high molecular weight (arsenic hydrocarbons and arsenic phospholipids) species. In this review we cover the intergrity of As species during collection, storage, sample preparation and measurement by HPLC-ICPMS and HPLC-HG-AFS. It is essential to ensure that As species, especially in waters and sediments, are not artefacts of the preservation or extraction procedure. Most samples can be stored frozen (−20 °C), but the stability of water and sediment samples is matrix dependent and depends on preservation technique applied. Arsenic cannot be extracted from samples using a single set of conditions but must be optimised for each sample type. Methanol–water mixtures with microwave heating are commonly used to extract polar As species from tissues while As-lipids required a non-polar solvent. Dilute acid can be used to increase the efficiencies of extraction of hard to extract tissue As species. Freeze drying is suitable for the drying of biotic material while sediments should not be dried before analysis. Extraction efficiencies are critically dependent on particle size. Polar As species have a wide variety of ionic characteristics thus complimentary chromatographic approaches utilising ion-exchange or reverse phase columns with modifiers are needed to separate all the As species. Arsenic-lipids require the use of a reverse phase column and gradient elution with high concentrations of organic solvents and require compensation for carbon enhancement effects in the ICPMS. Care must be taken that chromatographic peaks are not misidentified and matrix interferences accounted for that may influence quantification. Finally, to ensure accurate results, mass balances and extraction and column recoveries need to be determined at all steps. Methods need to be evaluated using As spikes and certified reference materials to provide a means of assessing the quality of results. [ABSTRACT FROM AUTHOR]

This is the seventh Atomic Spectrometry Update (ASU) to focus on advances in elemental speciation and covers a period of approximately 12 months from December 2013. This ASU review deals with all aspects of the analytical speciation methods developed for: the determination of oxidation states; organometallic compounds; coordination compounds; metal and heteroatom-containing biomolecules, including metalloproteins, proteins, peptides and amino acids; and the use of metal-tagging to facilitate detection via atomic spectrometry and relating to elemental speciation. The review does not specifically deal with fractionation, sometimes termed operationally defined speciation. The focus of the research reviewed includes those methods that incorporate atomic spectrometry as the measurement technique. However, because speciation analysis is inherently focused on the relationship between the metal(loid) atom and the organic moiety it is bound to, or incorporated within, atomic spectrometry alone cannot be the sole analytical approach of interest. For this reason molecular detection techniques, such as mass spectrometry, fluorescence and ultra-violet spectroscopy are also included where they have provided a novel approach to speciation analysis. As in previous years, As and Se speciation continues to dominate the current literature, with many derivative type papers being published, exploring all facets of the established analytical protocols used in these areas. Once again there has been an increase in the number of publications in the area of macromolecular analysis, particularly work concerned with metallomics or metalloproteomics and also tagging or labelling of organic molecules to make them detectable by atomic spectroscopy techniques. The use of atomic and molecular mass spectrometry in combination, either simultaneously on-line or sequentially off-line, continues to offer the best main-stream approach for most conventional applications, particularly when standards for the species under investigation are not available and high mass accuracy MS instrumentation can be used for identification. [ABSTRACT FROM AUTHOR]

A new sensitive chromatographic method has been developed for As speciation determination in anoxic pore waters. Starting from aliquots of 25 μL, the different As species As(iii), As(v), MMAAV and DMAAV were separated in less than 4 min by HPIC-ICP-MS using the IonPac® AG7-AS7 anion-exchange column set and dilute HNO3 as mobile phase. The detection limits were below or equal to 0.25 μg L−1 for each As species, which makes the method efficient to determine As speciation in poorly-contaminated sediments. In addition, no precipitation of iron and manganese (hydr)-oxides was observed since the anoxic samples were systematically carefully manipulated under nitrogen atmosphere. Chlorides were eliminated by the chromatographic separation, thus making possible speciation analysis in estuarine or seawater samples. The use of internal standard was not necessary due to good signal stability (＜10%) at m/z 75 over 4 h of analysis. An environmental application has also been successfully performed in the Marque River (Northern France). Inorganic As species were detected in pore waters at low concentrations [below 1 and 10 μg L−1, for As(v) and As(iii) respectively]. Others As species, identified as thioarsenic species, were also detected. [ABSTRACT FROM AUTHOR]

A non-chromatographic automated system for the speciation and determination of inorganic and trimethylantimony (TMSb) exploiting multisyringe flow injection analysis (MSFIA) with hydride generation (HG) and atomic fluorescence spectrometry (AFS) is described. A cationic minicolumn was used for retaining the methylated forms of Sb which can generate hydrides, minimizing errors in the inorganic antimony speciation step. The optimization was performed in a multivariate way by employing a three-variable Box–Behnken design and a multiple response strategy. So, this method allows the quantification of Sb using the external calibration with aqueous standards. The method is suitable for monitoring drinking, surface and ground waters according to regulations established by the EU directives for antimony (5.0 μg L−1), and it was applied to the speciation of inorganic antimony and TMSb in several spiked water samples with recoveries close to 100%. The detection limits were 0.03 μg L−1 for Sb(iii) and Sb(v) and 0.13 μg L−1 for TMSb. The method was satisfactorily applied to the determination of Sb(iii), Sb(v) and TMSb in different water samples collected in Balearic Islands, Spain. [ABSTRACT FROM AUTHOR]

Arsenic is ubiquitous in nature appearing in various chemical forms. The toxicity, environmental mobility and accumulation of As in living organisms depends on the form in which the element exists, thus requiring techniques which can identify specific forms whilst retaining their integrity during extraction and pre-treatment prior to measurement. Both organic and inorganic arsenic species may be present in food staples of both terrestrial and marine origin as well as natural waters, at sub ng l-1 to high mg l-1 levels. In this review, the speciation steps (sample preparation, species speciation and detection) most commonly used for the determination of As in food are described. High performance liquid chromatography separation with plasma source mass spectrometry is often the technique of choice due to its versatility, robustness and good detection limits. However, detection systems such as atomic absorption spectroscopy, atomic fluorescence spectrometry, and atomic emission spectrometry are also widely used and covered in this review together with some less utilised techniques. [ABSTRACT FROM AUTHOR]

The role and impact of chromium (Cr) on the environment and living organisms depends primarily on its chemical form. High toxicity of hexavalent Cr is well documented, while trivalent Cr is an essential micronutrient. In the last decades numerous analytical procedures have been developed for the determination of Cr(VI) in different sample matrices. To obtain reliable speciation data it is important to preserve species integrity during the sample storage, pre-treatment, extraction and the determination of Cr species. Among different speciation methods combination of high performance liquid chromatography (HPLC) with atomic spectrometry techniques provides comprehensive information on the presence of Cr species in a variety of sample matrices, while hyphenation of HPLC to inductively coupled plasma mass spectrometry (ICP-MS) represents the most powerful and the most sensitive analytical tool for Cr speciation. Precise isotope ratio measurement enables the application of isotope dilution techniques for the quantification of trace amounts of individual Cr species in various environmental and biological samples. Furthermore, enriched stable isotopes can be introduced as tracers to investigations on the fate and role of Cr in the environment and living organisms or to monitor the species transformation during the analytical procedure. Despite general understanding of Cr chemistry, which is closely related to its trivalent and hexavalent oxidation states and knowledge on conditions that may influence species transformation, there are still open questions that should be addressed to obtain reliable speciation analysis data. So, this article is focused mostly to overview recent developments in methodological approaches for Cr speciation in different sample matrices by applying HPLC and spectrometric techniques. Different procedures for preparation of isotopically enriched Cr spike solutions are critically evaluated. The advantages of their use as tracers to follow and account for species transformation during sample preparation and for the quantification of Cr species by HPLC-ID-ICP-MS are discussed. The importance of the use of adequate analytical methodologies and speciation analysis in the determination of Cr(VI) is highlighted in order to avoid inadequate conclusions to be made based on wrongly applied analytical methodologies. An increasing need to develop speciation procedures for selective determination of Cr(III) species is also emphasized. [ABSTRACT FROM AUTHOR]

The effect of common arsenic species on the ICP-MS signal working at a low liquid flow rate was investigated, taking into account the influence of the analytical concentration and of the matrix, comparing various sample introduction systems. Significant decrease (up to 65%) in the relative sensitivity of arsenite compared to arsenate was found, while methylarsonate, dimethylarsinate and arsenobetaine gave the same response (within 6%) as arsenate, throughout the 20–1000 μL min−1 liquid flow rate range. The effect was independent of the analytical concentration in the 1–100 μg L−1 range, and it was ascribed to processes related to both the sample introduction system and the ion generation and transport. Ion defocussing due to dissimilar kinetic energy of the arsenic ions generated from arsenite and arsenate was ruled out. Results obtained by various micronebulizer/spray chamber configurations showed that the temperature of the spray chamber is relevant in determining the relative responses of the arsenic species: heating the spray chamber at 60 °C caused a decrease in relative sensitivity of arsenite and dimethylarsinate compared to arsenate, while the arsenite-to-arsenate signal ratio was improved by cooling at 4 °C. The relative response of arsenite and arsenate was also significantly influenced by the presence of ammonium phosphate, which mitigated the difference between the species using conventional sample introduction devices. The influence of the chemical species on the ICP-MS signal was also investigated for species of other elements, finding significant differences in sensitivity for Hg, Se and Sn compounds when working at a low liquid flow rate. The results proved to have an effect on the accurate quantification of total concentration, as well as for arsenic speciation analysis by μHPLC/ICP-MS. [ABSTRACT FROM AUTHOR]

This is the fifth Atomic Spectrometry Update (ASU) to focus specifically on developments in elemental speciation and covers a period of approximately 12 months from January 2012. The International Union for Pure and Applied Chemistry (IUPAC) have evaluated speciation and provided a definition as follows: “speciation analysis is the analytical activity of identifying and/or measuring the quantities of one or more individual chemical species in a sample; the chemical species are specific forms of an element defined as to isotopic composition, electronic or oxidation state, and/or complex or molecular structure; the speciation of an element is the distribution of an element amongst defined chemical species in a system”. This review therefore deals with all aspects of the analytical speciation methods developed for: the determination of oxidation states; organometallic compounds; coordination compounds; metal and heteroatom-containing biomolecules, including metalloproteins, proteins, peptides and amino acids; and the use of metal-tagging to facilitate detection via atomic spectrometry. As with all ASU reviews1–5 the coverage of the topic is confined to those methods that incorporate atomic spectrometry as the measurement technique. However, in the spirit of meeting the needs of the subject, material is incorporated that is not strictly “atomic spectrometry”. For the most part, such procedures are those in which some form of molecular MS is used for speciation measurements, often in parallel with an elemental detector. As the content of this Update shows, the field is now maturing as evidenced by the extent to which the speciation of particular elements or technique combinations have been the subject of review articles. However, it is becoming increasingly difficult to ascertain the analytical details of the methodologies applied in speciation analysis, particularly where the paper is published in an ‘application’ based journal. [ABSTRACT FROM AUTHOR]