Hydride Generation Research Articles

PAN-templated synthesis of layered Co3O4 nanosheets for rapid reduction of 4-NP to 4-AP: Improved formation of unique Co3+-rich (440) facet on the crystal lattice of Co3O4

The efficient reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) using Co3O4 in NaBH4(aq) requires the precise control of hydride (Hδ-) and protic hydrogen (Hδ+) generation. Currently, this is achieved using (311) facet-dominated Co3O4 with Co2+-rich edges that favor Hδ- activation leading to poor performance. Herein, we employ the ladder-like structure of oxidized polyacrylonitrile (PAN) to fine-tune the growth of the (311)-to-(440) facets in layered Co3O4 nanosheets. This yields a balanced distribution of Co3+/Co2+ edge sites, leading to enhanced catalytic activity. Our catalyst is prepared by air-annealing a mixture of cobalt acetate (Co(OAc)2) and PAN at 500 °C. The mass ratio of Co(OAc)2 to PAN dictates the (311)/(440) facet ratio (i.e., Y). Specifically, a ratio of 0.25/0.4 (P-0.25–500) gives Y= 1.12. Meanwhile, at ratios of 0.05/0.4 (P-0.05–500) and 0.5/0.8 (P-0.5–500), Y increases to 1.25 and 1.27, respectively. XPS analysis confirms that the surface Co3+/Co2+ distribution (X) on P-0.25–50, P-0.05–500, and P-0.5–500 is 0.43, 0.41, and 0.39, respectively, highlighting a direct relationship between the (440) exposure and Co3+ concentration. The rate of 4-NP reduction (i.e., kapp) on P-0.25–500, i.e., ∼2.84 × 10−2 s−1 is 3.1x and 3.6x faster than P-0.05–500 (∼9.16 ×10−3 s−1) and P-0.5–500 (∼7.81 ×10−3 s−1), respectively. P-0.25–50's performance is comparable to that of state-of-the-art noble metal catalysts and higher than commercial Co3O4, and it maintains a decent catalytic retention of 88.84% after six recycles, demonstrating high stability. Our research presents a simple yet highly effective method for achieving balanced Hδ+ and Hδ- activation edges in Co3O4, resulting in superior 4-NP reduction activity.

The effect of selenium co-ingestion on mercury bioaccessibility in contaminated fish of the Amazon region

Mercury (Hg) is a toxic element that contaminates humans by consuming fish with high concentrations due to biomagnification in the food chain. This situation primarily impacts the riverside population in the Amazon region, as fish is their staple food. The interaction between selenium (Se) and Hg is well known due to their respective conceptual Pearson (soft-soft) characteristics. However, there needs to be more understanding of the impact of Se co-ingestion on Hg bioaccessibility. This scenario has prompted the investigation into the effects of consuming Se-rich food on the potential bioaccessibility of Hg when simultaneously ingesting contaminated fish. Cold vapor atomic absorption spectrometry (CV-AAS) measured Hg, and a hydride generator (HG-AAS) was used for Se. The results indicated that the piscivorous species Cichla sp. (Tucunaré fish) exhibited a Hg concentration over twice the limit established by the European Commission: 2.94 ± 0.21 μg g−1 for raw fish and 2.64 ± 0.16 μg g−1 for cooked fish. Concomitant ingestion of beans can reduce the potential bioaccessibility of Hg by 42% (68.4 to 25.8), and Brazil nuts co-ingestion can be reduced by 45% (68.4 to 23.1). However, due to the high fish consumption in the riverside population's diet, the Hazard Index (HI) and Target Hazard Quotient (THQ) values, including beans and Brazil nuts, exceeded the safe limit, even though THQ had decreased by 55%, and 66% with adding beans and Brazil nuts, respectively. These findings underscore the significant potential of Se in reducing Hg bioaccessibility through co-ingestion of foods containing this element. Additionally, it highlights the importance of considering regional dietary habits when assessing potential health risks. The results also sound like a warning about the food safety of the local communities.

Novel Palladium Coated Tungsten Coil Atom Trap for Ultra-Trace Determination of Selenium by Hydride Generation Atomic Absorption Spectrometry (HGAAS)

A new ultra-sensitive method was developed for selenium (Se) determination by combining a Pd-coated W-coil atom trap with hydride generation atomic absorption spectrometry (HGAAS). Firstly, gaseous hydrogen selenide, generated using a hydride generation system, was transported to an externally heated atom trap for in-situ preconcentration, where it was accumulated at 210 °C. Subsequently, the atom trap temperature was adjusted to 930 °C for revolatilization, resulting in the acquisition of a transient analyte signal within a very short time. The detection limit of 2.6 ng L−1 Se for a 90 s collection and a relative standard deviation of 2.4% for 0.01 µg L−1 Se (n = 14) were obtained. The devised trapping technique exhibited a remarkable 38-fold increase in sensitivity when compared to the conventional HGAAS method, as indicated by the characteristic concentration (C 0). The surface morphology was examined using scanning electron microscopy and energy dispersive spectroscopy. The proposed technique was validated by the analysis of certified reference materials (CRMs) and employed in the assessment of tap water samples. Statistical analysis using a t-test was conducted on CRMs and water samples, and the results showed no significant error.

Development of a New and Highly Sensitive Method for Arsenic Determination in Drinking Water Samples Using Au‐Coated W‐Coil Atom Trap Hydride Generation Atomic Absorption Spectrometry

AbstractA novel ultra‐sensitive gold‐coated tungsten‐coil atom trap coupled with HGAAS was developed for the first time for the determination of arsenic. The analytical methodology was based on transporting and in‐situ trapping of arsine produced by the hydride generation system onto a gold‐coated W‐coil trap for preconcentration via Ar and H2 gases. The trap surface was examined using scanning electron microscopy and energy‐dispersive X‐ray spectroscopy. SEM images revealed that the surface is covered with hexagonal and pentagonal structures on a micro scale with gold. The experimental parameters were optimized for both trap and non‐trap method. The enhancement factor for the characteristic concentration (C0) was determined to be 15.3 when compared with the non‐trap methods. For the trapping time of 120 s using the developed method, the limit of detection (LOD) and the precision were determined as 4.8 ng L−1 and 3.6 %, respectively. The interference effects of various hydride‐forming ions were examined in detail. The accuracy of this ultrasensitive methodology was successfully verified by analysis of certified reference materials and some drinking water samples.. t‐test was implemented to the water samples, the added and measured concentrations exhibited no statistically meaningful distinction at the 95 % confidence level.

A novel block copolymer containing gadolinium oxide nanoparticles in ultrasound assisted-dispersive solid phase microextraction of total arsenic in human foodstuffs: A multivariate optimization methodology

A new poly(3-hydroxy butyrate)-b-poly(dimethyl amino ethyl methacrylate) amphiphilic block copolymer containing gadolinium oxide nanoparticles (PHB-PDMAEMA-Gd2O3-NPs) were synthesized and used as composite adsorbent for extraction of total arsenic. Characterization of the composite adsorbent material PHB-PDMAEMA-Gd2O3-NP was studied using spectroscopic techniques. Plackett-Burman design and central composite design were employed to screening and optimization of the experimental parameters. This composite adsorbent was utilized in ultrasound assisted-dispersive solid phase microextraction (UA-dSPµE) for the determination of total inorganic arsenic in foodstuffs through hydride generation atomic absorption spectrometry (HG-AAS). It demonstrates a linear relationship across arsenic concentration range of 0.07–1.12 µg/L with a correlation coefficient (0.996). It’s showed an enrichment factor of 128 and a limit of detection 0.02 µg/L for total inorganic arsenic determination. Accuracy of the developed method was confirmed through the analysis of certified reference materials with 96.0–98.5% recovery. It proved to be significantly useful UA-dSPµE method for determining total inorganic arsenic in different foodstuffs.

Ultrasensitive determination of selenium in water and food samples by ICP-MS: UiO-66-NH2 for preconcentration and direct slurry hydride generation

BackgroundSelenium is an indispensable microelement for humans and food is the main source of selenium intake. As one of the best techniques for the determination of selenium, inductive coupling plasma-mass spectrometry (ICP-MS) features some unique advantages, such as wide linear range and high sensitivity. Nevertheless, it still remains a challenge to achieve the accurate and high sensitivity determination of ultra-trace selenium in food samples by ICP-MS owning to the high first ionization energy of selenium and interferences from sample matrices as well as isobaric interferences. ResultsIn this work, UiO-66-NH2 (metal organic framework, MOF) was fast synthesized by microwave method and employed for the preconcentration of ultra-trace selenium with an adsorption efficiency of nearly 100%. The selenium-adsorbed MOF was collected by filtration, and then simply converted to slurry for in situ hydride generation (HG) for sensitive detection of selenium by ICP-MS. Various factors affecting the adsorption of selenium by the MOF (including pH, adsorption time, and amount of MOF) together with main parameters of hydride generation (including concentrations of HCl and NaBH4) were carefully evaluated. Experimental results show that effective matrix separation can greatly reduce interference, with an excellent detection limit of 1 ng/L. The practicability and accuracy of this method were successfully confirmed by the determination of trace selenium in several food samples. SignificanceUiO-66-NH2 (MOF) was used as an effective adsorbent for the preconcentration of selenium prior to direct slurry sampling HG-ICP-MS determination. Direct slurry sampling avoided additional elution procedures and was conducive to eliminating matrix and isobaric interferences. High sensitivity and anti-interference determination were achieved for determination of ultra-trace Se in complex food samples.

Photoinduced NiH Catalysis with Trialkylamines for the Stereodivergent Transfer Semi-Hydrogenation of Alkynes.

We report a selectivity-switchable nickel hydride-catalyzed methodology that enables the stereocontrolled semi-reduction of internal alkynes to E- or Z-alkenes under very mild conditions. The proposed transfer semi-hydrogenation process involves the use of a dual nickel/photoredox catalytic system and triethylamine, not only as a sacrificial reductant, but also as a source of hydrogen atoms. Mechanistic studies revealed a pathway involving photo-induced generation of nickel hydride, syn-hydronickelation of alkyne, and alkenylnickel isomerization as key steps. Remarkably, mechanistic experiments indicate that the control of the stereoselectivity is not ensuing from a post-reduction alkene photoisomerization under our conditions. Instead, we demonstrate that the stereoselectivity of the reaction is dependent on the rate of a final protonolysis step which can be tuned by adjusting the pKa of an alcohol additive.

Possibilities and Limitations of ICP-Spectrometric Determination of the Total Content of Tin and Its Inorganic and Organic Speciations in Waters with Different Salinity Levels-Part 2: Separate Determination of Inorganic and Organic Speciations of Tin.

In this study, determination of the inorganic and organic forms of tin in waters of different salinities is considered. The possibility of the separation of speciations of tin using liquid-liquid extraction (LLE); precipitation with fluorides, iodides, ammonia, and iron (III) chloride; and sorption of organotin compounds (OTCs) was studied. The LLE and analyte precipitation methods proved to be ineffective. Inorganic and organic forms of tin were separated by the sorption of OTCs using silica gel sorbent Diapak C18. Under optimized conditions, a technique for the separate determination of the forms of tin in natural waters was developed. The technique combines hydride generation and microwave mineralization of solutions followed by ICP spectrometry. The inorganic forms of tin were determined after their solid-phase separation from organotin compounds. The lower limits of analyte quantification were 0.03 μg/L (ICP-MS) and 0.05 μg/L (ICP-OES), which provide separate determinations of inorganic and organic forms of tin in waters with different salinities. The content of OTCs in water was determined by subtracting the inorganic concentration from the total concentration of tin. The technique will allow a comprehensive assessment of the toxicological impact of tin speciations on the aquatic ecosystem.

UV-photochemical vapor generation coupled to hydride generation AAS in the study of dietary intake of Se, Hg, Cd, and Pb from fish

The consumption of fish by pregnant and lactating women is at the center of attention both from the point of view of ensuring healthy nutrition for fetal and neonatal development, and from the toxicological point of view. This research included a questionnaire survey on the frequency of fish consumption and the particular fish species consumed by 180 pregnant and lactating women in the Czech Republic, as well as the determination of Se, Hg, Cd, and Pb in the most commonly consumed species available on the Czech market. For this purpose, an analytical method for the determination of total selenium in biological samples using UV-photochemical vapor generation coupled to hydride generation atomic absorption spectrometry (UV-PVG-HG-AAS) was developed. This unique UV-photoreactor enables accurate and precise determination of Se with a detection limit of 0.007 mg/kg. Fish consumption by female respondents was generally low compared to the EU average. The determined Se contents in samples indicate a low intake of Se from fish in the Czech Republic; one third of the samples had Se contents below the detection limit. The highest Se contents were observed in the species Scomber scombrus, Sander lucioperca, and Thunnus albacares. The Hg content in fish samples did not exceed the EU maximum permissible values for mercury and methylmercury. The Tolerable Weekly Intake (TWI), which is 1.3 μg/kg of body weight per week, was not exceeded by any of the respondents. The maximum permissible value for Cd given by the European Commission was exceeded in the case of one sample of Scomber scombrus. Most of the samples had Cd content below the detection limit (0.002 mg/kg). The content of Pb in the analyzed samples was below the detection limit (0.013 mg/kg).

Rice Water—More a Source of Nutrition Elements or Toxic Arsenic? Multi-Element Analysis of Home-Made (Natural) Rice Water and Commercialized Rice-Based Products Using (HG)-ICP OES

Although rice is a well-known source of nutrients, it unfortunately accumulates As the most compared to other cereal plants. Due to the growing interest in rice-based cosmetics, the aim of the work was the multi-element analysis of various home-made (natural) rice waters and commercialized ready-to-use rice-based cosmetics for skin/hair. The total concentrations of Al, As Ca, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb, and Zn in raw rice and rice products were determined using inductively coupled optical emission spectrometry (ICP OES) after wet sample decomposition in the presence of concentrated HNO3. In the case of As, the hydride generation (HG) technique was used as a sample introduction system to the ICP OES instrument. Five different procedures, including washing/rinsing, soaking, boiling, and fermentation steps, and three rice types, i.e., white, brow, and jasmine, were used for this purpose. The effects of the water temperature, the contact time of rice grains with water, and the type of rice on the water-soluble concentrations of elements were examined and compared. A significant difference in the solubility of elements was observed depending on the type of rice, with the lowest percentage of extraction noted for brown rice. The best option was soaking unwashed rice grains in a six-fold excess of cold water for 30 min. The selection criterion was to preserve the highest content of essential elements (Ca (0.76–1.2 mg kg−1), Cu (9.2–43 ng k−1), Fe (0.096–0.30 mg kg−1), Mg (6.9–11 mg kg−1), Mn (0.16–10.32 mg kg−1), and Zn (0.083–0.25 mg kg−1)) with reduced to a minimum As level, i.e., <5 ng g−1 (2.8–4.8 ng g−1), making this water safe for consumption. In contrast, regularly drinking water after boiling or soaking rice grains in hot water carries the risk of consuming an excessive amount of this element due to As content exceeding the permissible value, i.e., 10 ppb. Finally, these home-made products were compared with commercialized cosmetics for skin/hair, with satisfactory results.

Fractionation of selenium isotopes during biofortification of Saccharomyces cerevisiae and the influence of metabolic labeling with 15N.

Isotope fractionation of metals/metalloids in biological systems is an emerging research area that demands the application of state-of-the-art analytical chemistry tools and provides data of relevance to life sciences. In this work, Se uptake and Se isotope fractionation were measured during the biofortification of baker's yeast (Saccharomyces cerevisiae)-a product widely used in dietary Se supplementation and in cancer prevention. On the other hand, metabolic labeling with 15N is a valuable tool in mass spectrometry-based comparative proteomics. For Se-yeast, such labeling would facilitate the assessment of Se impact on yeast proteome; however, the question arises whether the presence of 15N in the microorganisms affects Se uptake and its isotope fractionation. To address the above-mentioned aspects, extracellularly reduced and cell-incorporated Se fractions were analyzed by hydride generation-multi-collector inductively coupled plasma-mass spectrometry (HG MC ICP-MS). It was found that extracellularly reduced Se was enriched in light isotopes; for cell-incorporated Se, the change was even more pronounced, which provides new evidence of mass fractionation during biological selenite reduction. In the presence of 15N, a weaker preference for light isotopes was observed in both, extracellular and cell-incorporated Se. Furthermore, a significant increase in Se uptake for 15N compared to 14N biomass was found, with good agreement between hydride generation microwave plasma-atomic emission spectrometry (HG MP-AES) and quadrupole ICP-MS results. Biological effects observed for heavy nitrogen suggest 15N-driven alteration at the proteome level, which facilitated Se access to cells with decreased preference for light isotopes.

Determination and speciation of inorganic As in homeopathic medicines by HG-ICP OES method with no or minimal sample treatment before measurements

The analysis of homeopathic medicines for the content of total inorganic As by hydride generation (HG) hyphenated with the ICP OES detection was presented. Various forms of medicaments (sugar pellets, tablets, alcohol-based drops), containing Arsenicum album or Arsenicum iodatum in several potencies (C9–200, D6–10), as well as different sample preparation approaches (wet digestion, extraction, dissolution, dilution, direct analysis) before spectrometric measurements were studied. The influence of the undecomposed sample matrix (mainly sugar and alcohol) on the HG process of As was examined in detail. Under optimal conditions found, simplified sample preparation procedures for the determination of As traces were proposed. The suitable sensitivity, the limit of detection of As < 0.1 ng g−1, the precision within 0.31–7.4 % (as RSD), and the adequate trueness (94.9–113 % as confirmed by the recovery test) were achieved. Using the species-selective HG conditions and the developed direct analysis method, the speciation of As in arsenic drops without any prior chromatographic separation of As(III) and As(V) was carried out. The applicability of the developed strategies was demonstrated by the determination of As in 13 homeopathic products available on the Polish market.

Cellular uptake and biotransformation of arsenate by freshwater phytoplankton under salinity gradient revealed by single-cell ICP-MS and CT-HG-AAS

Environmental context Freshwater phytoplankton are involved in the biogeochemical cycling of arsenic within aquatic ecosystems via uptake processes. Rather than determining the mean arsenic content in a population of freshwater phytoplankton, we investigate the heterogeneity of arsenic uptake by single-cell ICP-MS. Our data show that arsenic distribution within a cell population may be highly heterogeneous, measured at the femtogram per cell level, and are affected by species and salinity. Rationale An advanced technique has been developed for analysing intracellular elements at the single-cell level using single-cell inductively coupled plasma mass spectrometry (SC-ICP-MS). Compared with conventional inductively coupled plasma mass spectrometry (ICP-MS) analysis, SC-ICP-MS provides uptake data with greater biological relevance. In this study, the use of SC-ICP-MS enabled the quantification of metal concentrations on an individual cell basis down to the femtogram (fg) per cell level. Methodology Three freshwater phytoplankton cells, namely Staurastrum paradoxum (S. paradoxum), Pediastrum duplex (P. duplex) and Scenedesmus acutus (S. acutus), were incubated in 0.1 µmol L−1 arsenate (AsV) solution for 14 days at varying salinity. Cold trap hydride generator atomic absorption spectrometry (CT-HG-AAS) was used to investigate the biotransformation of arsenate under varying salinity conditions. Results The results reveal that cellular arsenic levels decreased as salinity increased in P. duplex and S. paradoxum but increased in S. acutus. The SC-ICP-MS data, which show uptake of AsV by freshwater phytoplankton, were in good agreement with those produced using ICP-MS analysis. Various arsenic management strategies were seen in the phytoplankton species: P. duplex converted it to methylated forms; S. acutus produced organoarsenicals; and S. paradoxum reduced arsenate (AsV) to arsenite (AsIII) and excreted it. Our study also showed changes in the physiological status of phytoplankton following salt stress and arsenic exposure. Discussion Our results confirm the efficacy of SC-ICP-MS in precisely determining arsenic distribution at the single-cell level and reveal differences in intraspecies mechanisms for arsenic cycling in freshwater ecosystems.

Chemical vapor generation of tungsten for atomic spectrometric determination: Homogeneous sensitizer and mechanism study

BackgroundInductively coupled plasma-mass spectrometry (ICP-MS) is one of the most powerful instrumental techniques for the determination of tungsten for its low detection limit and wide linear range, while it remains challenging since the analytical performance can be affected by complicated sample matrix. Chemical vapor generation (CVG) harbors the potential to be an alternative to conventional solution nebulization for sample introduction to reduce matrix effect. However, the CVG of tungsten was low in efficiency. It is clear that green and homogeneous enhancement for CVG of tungsten is desired and the mechanism is worth in-depth investigation. ResultsTwo green and homogeneous enhancement systems for CVG of tungsten were studied, including photochemical vapor generation (PVG) and hydride generation (HG) with sensitizers, Fe3+ and DDTC, respectively. Under optimal conditions, the limits of detection (LODs) were 0.02 μg L−1 for the PVG and 0.003 μg L−1 for the HG, respectively. For PVG, the Fe3+/Fe2+ cycling, free radical species, gaseous product, and the chemical speciation evolution of W in the PVG process were studied in detail. Photo-Fenton effect, generated reductive radical ·CO2−, gaseous product Fe(CO)5, and the mixed valence of W5+/W6+ in the PVG process were found to be crucial for the enhancement. As for HG, the complexation between W(VI) and DDTC might be conducive to the enhanced HG efficiency. SignificanceThis work not only in-depth expands the element scope of CVG, but also investigates the enhancement mechanisms experimentally, which might render a deep insight into the CVG processes and foreshadow new guidelines for screening green and efficient homogeneous sensitizers for CVGs of more elements in the future.

New Ultrasound-Assisted Extraction Sample Preparation Procedure for the Fast Determination of Total Sn in Canned Tomatoes by HG-ICP OES

An analytical method with no need for laborious sample preparation before determining the total Sn in canned tomatoes by hydride generation (HG) coupled to inductively coupled plasma optical emission spectrometry (ICP OES) was developed. The ultrasound-assisted extraction with various reagents (acidic media: HCl, HNO3, CH3COOH or aqua regia and alkaline: TMAH) that could replace the traditional wet sample digestion in the presence of a concentrated HNO3-H2O2 mixture was tested and compared. Tin hydride was generated directly from the prepared sample solution in the reaction with 1% NaBH4 or via prior acidification with a 1 mol L−1 HCl. The effect of the sample pretreatment before HG-ICP OES measurements on the Sn signal was also examined. The best results were obtained with aqua regia as the extraction medium, followed by a simple two-fold dilution of the sample extract combined with the addition of L-cysteine. The developed method was characterized by a detection limit of Sn at 0.74 ng g−1, a precision of better than 6%, and a trueness, verified by the analyte spike-and-recovery test, of 98.4–104%. Its usefulness was demonstrated by the determination of Sn in seven canned tomatoes.

Possibilities and Limitations of ICP-Spectrometric Determination of the Total Content of Tin, Its Inorganic and Organic Speciations in Waters with Different Salinity Levels-Part 1: Determination of the Total Tin Content.

This paper considers the features of determining the total tin content in waters with different salinity. Direct ICP-spectrometric analysis of sea waters with a salinity of more than 6‱ significantly reduced the analytical signal of tin by 70% (ICP-MS) and 30% (ICP-OES). The matrix effect of macrocomponents was eliminated by generating hydrides using 0.50 M sodium borohydride and 0.10 M hydrochloric acid. The effect of transition metals on the formation of tin hydrides was eliminated by applying L-cysteine at a concentration of 0.75 g/L. The total analyte concentrations, considering the content of organotin compounds, were determined after microwave digestion of sample with oxidizing mixtures based on nitric acid. The generation of hydrides with the ICP-spectrometric determination of tin leveled the influence of the sea water matrix and reduced its detection limit from 0.50 up to 0.05 µg/L for all digestion schemes. The developed analysis scheme made it possible to determine the total content of inorganic and organic forms of tin in sea waters. The total content of tin was determined in the waters of the Azov and Black seas at the levels of 0.17 and 0.24 µg/L, respectively.

A portable piezoelectric transformer microplasma optical emission spectrometry for the determination of mercury

Miniaturization of microplasma-based optical emission spectrometry (OES) has gained great attention due to the advantages of simplicity, compactness, and cost-effectiveness. However, the energy feed-in affects the generation, maintenance and excitation capability of discharge microplasma, which also limits the potential of microplasma for portable OES. Herein, we report that a piezoelectric transformer-driven microplasma (PTM) was first utilized as an excitation source of miniature OES for quantitative analysis of mercury (Hg). A piezoelectric transformer (PT) can directly convert mechanical energy into electrical energy and emanate plasma at the wire of the output distal end, which provides a path to construct microplasma devices without an extra high voltage power supply. A syringe needle acted as another ungrounded electrode, which was hung a proper distance below the PT output, to generate glow discharge. Hg was effectively converted into volatile species by hydride generation (HG) and transferred into PTM through the syringe needle by carrier gas (argon). Under the optimized experimental conditions, Hg was detected in the range of 10–1000 μg/L, with a limit of detection (LOD) of 2.8 μg/L by using the analytical line of Hg 253.65 nm. The accuracy and practicability of the proposed method were validated by analyzing the Certified Reference Materials (CRMs, dogfish liver and soil) and real water samples with satisfied results. In addition to no need of high voltage power supply and closed circuit, this HG-PTM-OES system features low power consumption, small size, light weight, sturdiness and high safety, which would be beneficial to fabricate a miniaturized and portable device for on-site environmental monitoring.

Speciation of Inorganic Arsenic in Retorted Oil Shale Slurry by Hydride Generation Atomic Absorption Spectrometry (HG AAS) after Ultrasound-Assisted Acid Extraction

An analytical method for determination of inorganic arsenic species in retorted oil shale slurry by atomic absorption spectrometry coupled to hydride technique with ultrasound assisted acidic extraction is reported. Trivalent arsenic measurement employed sample stabilization with a pH 4.5 prior to reaction with the reducing agent and analysis. In contrast, total inorganic As depended upon the pre-reduction of As(V) to As(III) with KI and ascorbic acid in 6.0 M HCl and of As(V) was estimated by the difference of the total inorganic As and As(III) concentrations. The limit of quantification was 3.7 mg kg−1 for As(III) and 1.3 mg kg−1 for itAs.

Spray assisted preconcentration method combined with HPLC – Continuous flow hydride generation – FAAS for inorganic arsenic speciation in olive oil samples

Speciation analysis of arsenic in edible oils is an important topic in terms of the assessment of its risks for human health and the quality of edible oils. In this study, high performance liquid chromatography – continuous flow hydride generation – flame atomic absorption spectrometry (HPLC-CFHG-FAAS) system after vortex assisted reverse phase spray-based fine droplet formation liquid phase microextraction (VA-RP-SFDF-LPME) method was proposed to qualify/quantify arsenite and total arsenic. Limit of detection (LOD) and limit of quantification (LOQ) for arsenite were calculated as 2.86 µg kg–1 (as As) and 9.52 µg kg–1 (as As), respectively. After the extraction/preconcentration process, a prereduction was carried out in the presence of 0.010 mol/L HCl (containing 0.39% L-cysteine) with heat (90 ± 5 oC) for the determination of total arsenic content while arsenite was directly determined via the developed system. Recovery for arsenite and total inorganic arsenic were in the range of 91.5 – 120.4% and 90.0 – 104.4%, respectively. The developed method is proposed for the analysis of olive oil samples containing inorganic arsenic species. This is the first study to carry out the inorganic arsenic speciation in olive oil by HPLC-CFHG-FAAS system after the preconcentration of the species by the VA-RP-SFDF-LPME system. For the matrix including arsenite and arsenate, the developed method can be safely used to find the concentration of both species accurately.

Given the high intake of potatoes by the world population, reliable methodologies with very low limits of detection are needed for the determination of highly toxic elements such as arsenic. For that purpose, graphite furnace atomic absorption spectrometry could be considered one of the techniques of choice; notwithstanding the matrix effect prevented its application in arsenic determination in potatoes as

Given the high intake of potatoes by the world population, reliable methodologies with very low limits of detection are needed for the determination of highly toxic elements such as arsenic. For that purpose, graphite furnace atomic absorption spectrometry could be considered one of the techniques of choice; notwithstanding the matrix effect prevented its application in arsenic determination in potatoes as the analytical signal was absolutely depleted. The potential interferent was searched among the mineral content. As a result, it was found that the interference presumably could be attributed to phosphate. Attempts to overcome the matrix interference by different sample digestion methodologies, chemical modification and temperature variation in the graphite furnace ashing and ashing / atomization stage respectively, were unsuccessful. Consequently, an alternative methodology for determining arsenic in potatoes using hydride generation microwave induced plasma optical emission spectrometry was developed. Limit of detection was 0.0030 mg kg-1 in fresh potatoes. The developed method is a robust, simple and low cost alternative for total arsenic safe monitoring of this highly consumed worldwide vegetable.