Hydride Generation Atomic Absorption Spectrometry Research Articles

Optimization of vortex-assisted ionic liquid dispersive liquid–liquid microextraction by experimental design prior to hydride generation atomic absorption spectrometry for determination of selenium species in food, beverage and water samples

We applied novel vortex-assisted ionic liquid dispersive liquid-liquid microextraction (VA-IL-DLLME) method to preconcentration and extraction of Se(IV) ions from water, beverage and food samples. The method was optimized using central composite design combined with the response surface analysis. After extraction, inorganic selenium species (total Se, Se(IV) and Se(VI)) were determined by hydride generation atomic absorption spectrometry. 1-n-Octyl-3-methylimidazolium bis(trifluoromethane)-sulfonamide [C8mim NTf2] and tetrahydrofuran were used as the extraction and dispersive solvents, respectively. Applied vortex assisted the extractant dispersion and accelerated the mass transfer process. Obtained optimum conditions for microextraction procedure are as follows: mass of [C8mim NTf2], pH, extraction time and THF volume should be equal to 85 mg, 6.8, 15 min and 730 μL, respectively. Under these conditions, we observed linear range, limit of detection and enrichment factor equal to 5−500ng L−1, 1.5 ng L−1 and 120, respectively. We also fount linear regression coefficients in the dependence between Absorbance and Se(IV) concentration: Absorbance = 0.0652 CSe(IV) + 0.0185. We added 200 μg kg−1 of Se(IV) to selected food samples and 100 ng L−1 of Se(IV) to selected waters and beverages. Relative standard deviations and recovery values were within the ranges of 2.4–3.5 % and 92.7÷103.4 %, respectively. The optimized VA-IL-DLLME method reported here provides high extraction efficiency, fast extraction and lower detection limit without a heating step than alternative microextraction methods. This method also requires environmental solvents for determination and preconcentration of trace Se species in the selected samples. In addition, the reported VA-IL-DLLME procedure is the first method which use [C8mim NTf2] as extraction solvent for the preconcentration and separation of Se(IV) ions.

Interference-free determination of arsenic in urine by atomic absorption using two-stage probe atomization in a graphite furnace

Inductively coupled plasma mass spectrometry, hydride generation atomic absorption spectrometry and graphite furnace atomic absorption spectrometry are presently used to determine total arsenic in urine, but after labor consuming sample pretreatment. Therefore, we proposed a new approach to solve this problem using two-stage probe atomization. High-resolution continuum source graphite furnace atomic absorption spectrometer was equipped with the probe accessory for that. The sample consisting of 15 μL urine and 20 μg Pd-modifier was dried on the furnace bottom at smooth heating up to 120 оС and atomized at 2300 оС with internal Ar flow. The resulting vapors of As condensed on a tungsten probe installed above the dosing hole. At the same time, Ar flow removed an essential part of the matrix components without condensation. At the second atomization stage at 2300 оС and interrupted internal gas flow, the probe was lowered into the furnace and heated by electric current to accelerate condensate evaporation. This procedure fully separates the analytical signal from the finely structured molecular background. Matrix interference disappears due to significantly different rates of As and urinary phosphates binding with Pd at temperature of 120 °C and distillation on the probe. The limit of As detection in urine is 1.5 μg L−1 and quantification range is 50–1000 μg L−1 that almost covers the entire patients' urine concentration range of interest for environmentalists and physicians.

The Total Antioxidant Status, Serum Selenium Concentrations and the Ultrasound Assessment Carotid Intima Media Thickness in Patients with Arterial Hypertension

The objective of the study was to establish the correlation between serum selenium concentrations, total antioxidant status, and the carotid intima media thickness in ultrasound assessment in patients with arterial hypertension. A group of 76 people suffering from arterial hypertension was qualified to participate in the study. The mean age of the respondents was 53.48 ± 12.78. Serum selenium concentrations (Se-S) and total antioxidant status (TAS) were determined in all respondents. Se-S were determined by hydride generation atomic absorption spectroscopy (HGAAS). The antioxidant status was assessed by the enzyme-linked immunosorbent assay (ELISA). In addition, an ultrasound exam of the carotid arteries was performed, and the intima media thickness (cIMT) was measured. In the study group, Se-S and TAS were 89.73 ± 18.99 µg/L and 1.18 ± 0.35 mM. However, the cIMT measured using ultrasound was 0.68 ± 0.15 mm. cIMT was significantly greater in patients with arterial hypertension with Se-S < median in comparison to patients with arterial hypertension with Se-S ≥ median (0.73 ± 0.19 mm vs. 0.65 ± 0.10 mm, p < 0.05), as well as in patients with arterial hypertension with TAS < median than in patients with arterial hypertension with TAS ≥ median (0.79 ± 0.18 mm vs. 0.56 ± 0.13 mm, p < 0.05). In regression analysis, older age, higher BMI, smoking, and lower serum selenium concentrations were independently correlated with the greater cIMT. Higher BMI and smoking were independent risk factors for the lower TAS, and the use of ACE inhibitors, β-blockers, and higher Se-S were independent factors of protection against the lower TAS. In patients with arterial hypertension, the lower total antioxidant status due to lower serum selenium concentrations may be correlated with an increase of the carotid intima media thickness measured using ultrasound.

Optimized preconcentration method using magnetic dispersive solid-phase microextraction with GO–γFe2O3nanoparticles for the determination of Se in fish samples by FIA-HG-AAS

Magnetic nanoparticles of GO–γ-Fe2O3were applied for the preconcentration of Se in fish samples and determination by hydride generation atomic absorption spectrometry and flow injection analysis.

Assessment of Arsenic in Groundwater of Southwestern Haryana, India and Chemical Body Burden Caused by its Ingestion

Abstract This study was undertaken to quantify the naturally occurring arsenic in the groundwater and chemical body burden caused by its ingestion at some villages of Fatehabad district, Haryana, India. The arsenic levels in groundwater were quantified by hydride generation atomic absorption spectrometry (HG-AAS). Arsenic concentration in the groundwater was found to be in the range of &amp;lt;0.05 to 4.53 μg L–1 which is within WHO and BIS acceptable limits (10 μg L–1). The significant positive correlation between pH - As (r=0.38**; P&amp;lt;0.01) showed that arsenic is more soluble in water at higher pH values. Oral arsenic exposure via groundwater ingestion ranged from &amp;lt;0.003 to 0.31 μg kg–1 day–1 which is significantly lower than WHO and BIS acceptable level (0.68 μg kg–1 day–1). The calculated non-cancer health risk was &amp;lt;1.0 which indicated that chemical burden caused by arsenic through drinking water in the study area is not a cause of concern. The calculated carcinogenic health risk was in the range of &amp;lt;5.06E-06 - 4.59E-04 which is slightly higher than acceptable limits.

First Extensive Polyphenolic Profile of Erodium cicutarium with Novel Insights to Elemental Composition and Antioxidant Activity.

Erodium cicutarium is known for its total polyphenolic content, but this work reveals the first highly detailed profile of E. cicutarium, obtained with UHPLC-LTQ OrbiTrap MS4 and UHPLC-QqQ-MS/MS techniques. A total of 85 phenolic compounds were identified and 17 constituents were quantified. Overall, 25 new compounds were found, which have not yet been reported for the Erodium genera, or the family Geraniaceae. Along with methanolic extracts, the so far poorly investigated water extracts exhibited in vitro antioxidant activity according to all performed assays, including the ferric reducing/antioxidant power assay (FRAP), 2,2-diphenyl-1-picrylhydrazyl assay (DPPH), 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) assay (ABTS) and cupric ion reducing antioxidant capacity assay (CUPRAC). Elemental composition analysis performed with inductively coupled plasma atomic emission spectrometry (ICP-AES) and, additionally, hydride generation atomic absorption spectrometry (HydrEA-ETAAS) showed six most abundant elements to be decreasing as follows: Mg>Ca>K>S>P>Na, and gave first data regarding inorganic arsenic content (109.3-248.4 ng g-1 ). These results suggest E. cicutarium to be a valuable source of various phenolic compounds with substantial potential for further bioactivity testing.

Survey of Arsenic Contents in Shell-Medicament Used as Chinese Medicine

The shells of mollusks such as Concha Haliotidis (Shijueming), Concha Arcae (Walengzi), Concha Ostreae (Muli) and Pearl are used as ingredients in certain Chinese medicines. Such shells can accumulate heavy metals. Because arsenic is toxic to humans, an investigation of arsenic content in these medicaments is necessary to protect the health of humans. The shells of mollusks were digested with diversified acids, and then surveyed by hydride generation atomic absorption spectrometry. The arsenic content was 4.45, 3.41, 1.93 and 5.28 ppm in Pearl, Muli, Shijueming, and Walengzi respectively. All were below the announced levels of safe and adequate daily dietary intake for humans.

Determination of inorganic arsenic in Argentinean rice by selective HGAAS: Analytical performance for paddy, brown and polished rice

Inorganic As (iAs) species require strict monitoring in foodstuff due to their toxicity. Rice is of particular concern, with recent legislations establishing limits for these species. In this work we develop a method based on selective hydride generation atomic absorption spectrometry (HGAAS) for the determination of iAs in different types of rice (polish, parboiled, brown and paddy rice). The multivariate design of experiments used for optimization showed interactions between different factors involved in hydride generation. Matrix effects were systematically studied, where the flow rate of the carrier gas proved to be a critical parameter for the minimization of matrix interferences. Nevertheless, matrix-matching was found to be necessary for accurate quantification of paddy rice samples. Comparison of the iAs concentrations obtained by HGAAS and HPLC-ICP-MS showed non-significant differences between the methods. Analysis of 86 rice samples from the province of Entre Ríos showed relatively low concentrations of iAs (<282 μg kg−1 for paddy rice and <120 μg kg−1 for polished rice), regardless of total As concentrations (which ranged from 63 μg kg−1 to 932 μg kg−1), suggesting that the rice analyzed tends to accumulate As in its organic forms.

Speciation of arsenic in wastewater samples based on pyributicarbamate /ionic liquids by dispersive liquid-liquid microextraction

A simple and applied method based on O-3-Tert-butylphenyl N-(6-methoxy-2-pyridyl)-N-methylthiocarbamate (Pyributicarbamate; TBMPMTC) was used for arsenic speciation (AsIII and AsV) in urine and water samples by dispersive liquid-liquid microextraction (DLLME) procedure. The concentrations of arsenic in the liquid phase were determined by hydride generation atomic absorption spectrometry in the presence of flame accessory (HG-AAS). By procedure, a mixture of ionic liquid (0.1 g, [APMIM][PF6]@[HMIM][PF6]), acetone (0.2 mL) and pyributicarbamate was injected into wastewater sample containing arsenic (AsIII and AsV) ions, which were already extracted by pyributicarbamate at the optimized pH. The task-specific ionic liquid (TSIL) of 1-3-aminopropyl)-3-methyl-imidazoliumhexafluorophosphate [APMIM][PF6] was chemically synthesized and used for increasing of As(V) extraction in the liquid phase. As(III) was extracted based on the sulfur bond of pyributicarbamate at pH=5.3. As (V) can be extracted by amine group of TBMPMTC and [APMIM][PF6] at pH=3.0 (As(V) --- : NH2). The influence of parameters was studied.

Alcohol-DES based vortex assisted homogenous liquid-liquid microextraction approach for the determination of total selenium in food samples by hydride generation AAS: Insights from theoretical and experimental studies

This research article proposes a simple, quick, green and cheap approach for the determination of total selenium in food samples using alcohol-DES based vortex-assisted homogenous liquid-liquid microextraction (alcohol-DES-VA-HLLME) combination with hydride generation atomic absorption spectrometry (HG AAS). Analyte, complexing agent and working pH were Se(IV), Sudan-II and pH 4.0, respectively. In order to analyze the nature of the chemical interaction between Se(IV) ion and Sudan-II ligand, experimental results were supported with computational chemistry tools calculating quantum chemical descriptors like frontier orbital energies, hardness, softness, electronegativity, electrophilicity, nucleophilicity, transferred electron from the ligand to ion, electron donating power, electron accepting power, complexation energy, molecule-ion interaction energy. In addition, the alcohol-DES-VA-HLLME method was earned a good detection limit of 3.5 ng L−1 and a wide calibration curve in the concentration range of 12–300 ng L−1 (r: 0.9981). The validity of the method was evaluated by analyzing the two standard reference material (SRMs). The recoveries and relative standard deviations for 25 and 100 ng L−1 of Se(IV) (N:5) were in the range of 1.2–2.5% and 92.1–103.7% respectively, which proved acceptable. The analytical results showed that the proposed method had important features such as cheapness, green, quick extraction and reuse, which made it attractive for the determination and efficient extraction of total selenium in the food samples.

Speciation of Antimony in Injectable Leishmanicidal Drugs by Lowering Citric Acid Concentration Used in Hydride Generation Atomic Absorption Spectrometry Analysis

This study proposes a procedure for speciation of antimony by hydride generation atomic absorption spectrometry in pentavalent antimony drugs. The SbIII content was determined by selective generation of SbH3 in medium with higher SbV concentration using 4 to 20-fold lower citric acid solutions than recommended in the available literature. The multivariate optimization of the methods was performed through factorial design followed by a central composite design (CCD). The limit of detection (LOD) and limit of quantification (LOQ) were calculated at 0.15 and 0.05 µg L-1 and 0.48 and 0.17 µg L-1, for total Sb and SbIII, respectively. The relative standard deviation (RSD) values ranged from 3.1 to 19.6% and 9.1 to 20.1%, while recovery ranged from 95.6 to 102.3% and 89.1 to 108.1%, for total Sb and SbIII, respectively. This method was applied for the analysis of meglumine antimoniate samples. Total Sb and SbIII concentrations ranged from 79.2 to 101.1 mg mL-1 and 0.08 to 0.41 mg mL-1, respectively.

Analysis of total arsenic content in purchased rice from Ecuador

Natural and anthropogenic sources contribute to arsenic contamination in water and human food chain in Andean countries. Human exposure to arsenic via rice consumption is of great concern in countries where this crop is the dominant staple food, and limited information is available on the arsenic contamination on rice in Ecuador. This work was to contribute to the lack of knowledge analysing total arsenic by hydride generation-atomic absorption spectrometry in the samples of white, brown and parboiled rice purchased in Ecuadorian markets and produced in the two main rice wetlands in Ecuador, Guayas and Los Ríos, were carried out. For the samples from Guayas, arsenic concentration in white, brown and parboiled rice were 0.174 ± 0.014, 0.232 ± 0.021, and 0.186 ± 0.017 mg/kg respectively, whereas samples of white rice from Los Ríos showed a total arsenic level of 0.258 ± 0.037 mg/kg. This last arsenic concentration exceeds recommended maximum permissible limit by the FAO/WHO. Obtained data have available to estimate the Ecuadorian dietary exposure revealing serious health risk for population.

Speciation of arsenic (III,V) based on methyltrioctylammonium mercaptobenzoate and centrifuging dispersive liquid-liquid microextraction in water and blood samples

A novel analytical method based on centrifuging dispersive liquid-liquid microextraction (CD-LLME) procedure for pre-concentration of As (III) has been developed prior to determine by hydride generation atomic absorption spectrometry (HG-AAS). In this method, 0.1 g of a task-specific ionic liquids (methyltrioctylammonium 2-mercaptobenzoate; TOMAS; TSIL) as the extracting and complexing solvent and acetone as dispersant solvent were rapidly added into the water and blood samples at pH 4.5. The As (V) is simply calculated by difference between total concentration and inorganic forms As (III) in liquid samples. By optimizing parameters, the enrichment factor (EF) was obtained 9.8 and 49.6 for blood and water samples, respectively. The limit of detection (LOD) of 22.4 ngL-1 and 4.3 ngL-1 were achieved for 10 mL and 50 mL of As(III) in blood and water samples, respectively (RSD&lt;%5). The real samples were validated by certified reference material (CRM) by proposed procedure.

Speciation analysis of inorganic As and Sb in urban dust using slurry sampling and detection by fast sequential hydride generation atomic absorption spectrometry.

In this work, a methodology for chemical speciation analysis of inorganic As and Sb in urban dust using slurry sampling and detection by fast sequential hydride generation atomic absorption spectrometry is proposed. Doehlert design and desirability function were used to find the optimum conditions for hydride generation (1.0molL-1 HCl and 0.9%mv-1 NaBH4). The accuracy of the analytical method was evaluated by analysis of reference material fly ash (BCR 176R), addition and recovery tests for inorganic As species, and comparison of independent methods for Sb determination in urban dust samples. The determination of the total concentrations of As and Sb and their inorganic species presented good accuracy, between 80 ± 1 and 101 ± 6%. Precision was expressed as the relative standard deviation and was better than 4.7% (n = 3). The limit-of-quantification values were 0.23 and 1.03mgkg-1 for As and Sb, respectively. The methodology was applied to eight samples of dust collected in an urban area of Salvador and Jaguaquara cities, Bahia, Northeast, Brazil, with an aerodynamic size lower than 38μm. Concentrations of pentavalent inorganic species (iAs5+ and iSb5+) in relation to trivalent species (iAs3+ and iSb3+) were found in urban dust collected in the city of Salvador, which are regarded as more toxic for both elements. The enrichment factor and geoaccumulation index (Igeo) values showed that for some samples, the concentrations of iAs and iSb presented strong enrichment and, and regarding environment, strong to moderately polluted by iAs and iSb, with an indication of anthropogenic contributions. The occurrence of these inorganic constituents in the urban area of Salvador can be related with intense industrial activities and vehicular traffic.

Evaluation of arsenic field test kits for drinking water: Recommendations for improvement and implications for arsenic affected regions such as Bangladesh

Arsenic field test kits are widely used to measure arsenic levels in drinking water sources, especially in countries like Bangladesh, where water supply is highly decentralized and water quality testing infrastructure is limited. From a public health perspective, the ability of a measurement technique to distinguish samples above and below relevant and actionable drinking water standards is paramount. In this study, the performance of eight commercially available field test kits was assessed by comparing kit estimates to hydride generation atomic absorption spectroscopy (HG-AAS) analyses. The results of tests that control for user-dependent color matching errors showed that two kits (LaMotte and Quick II kits) provided accurate and precise estimates of arsenic, four kits (Econo-Quick, Quick, Wagtech and Merck kits) were either accurate or precise, but not both, and two kits (Hach and Econo-Quick II kits) were neither accurate nor precise. Tests were performed for arsenic concentration ranges commonly found in natural waters and treated waters (such as community drinking water filter systems), and also on laboratory generated arsenic standards in DI water. For those kits that did not perform well, test strips often produced colors too light compared to manufacturer-provided arsenic color calibration charts. Based on these results, we recommend stakeholders carefully re-consider the use of poorly performing field test kits until better quality control of components of these kits is implemented. In addition, we recommend that field test kit manufacturers provide suitable internal standards in every kit box for users to verify the veracity of manufacturer provided color charts.

Levels of mercury and arsenic contamination in popular fish and shrimp brands consumed in Saudi Arabia

ABSTRACT . Fish and shrimp are public sources of healthy protein for a large fragment of the Saudi population. Therefore, the present work was conducted to assess the level of possible arsenic (As) and mercury (Hg) con­tamination of these sea foods. Eight species of fish and two species of shrimp were collected from the local mar­kets of Eastern Province, Saudi Arabia. Mercury and arsenic concentration of samples was determined by hydride generation atomic absorption spectrometry (HG-AAS). Highest average concentration of total Hg was found in Siganus canaliculatus (0.54 ± 0.06 µg/g) while the lowest level was detected in Lethrinus miniatus (0.24 ± 0.07 µg/g). For shrimp species, the levels varied from 0.13 to 0.91 µg/g for mercury and 0.19 to 0.53 µg/g for arsenic. The rank order of shrimp species based upon mercury level was Penaeus semisulcatus > Penaeus indicus ; whereas based upon arsenic level it was almost similar. Mean levels of both Hg and As in all the species studied are lower than the limits set by international health agencies; 0.550 µg/g for mercury and 6.0 µg/g for arsenic. KEY WORDS : Arabian Gulf, Fish, Shrimp, Arsenic, Mercury Bull. Chem. Soc. Ethiop. 2019 , 33(3), 573-578. DOI: https://dx.doi.org/10.4314/bcse.v33i3.17

Ultrasonic-assisted micro solid phase extraction of arsenic on a new ion-imprinted polymer synthesized from chitosan-stabilized pickering emulsion in water, rice and vegetable samples.

Pickering emulsion polymerization has been employed for the Ultrasonic assisted-micro solid phase extraction (UA-µSPE) of ultra trace arsenic species by a new magnetic ion imprinted polymer (MIIP) prior to hydride generation atomic absorption spectrometry. 2-acetyl benzofuran thiosemicarbazone (2-ABT) as a new chelating agent and core- shell hydrophobic magnetic nanoparticles was synthesized and the polymerization was carried out at the presence of arsenic - ligand complex, crosslinker, monomer, initiator, stabilizing agent and water-oil emulsion magnetic carrier. In second step, the nanoparticles and polymers were characterized. The analytical parameters such as pH, amount of polymer and ultrasonic time were selected and optimozed by Plackett-Burman and Box-Behnken designs respectively. Linear dynamic range, detection limit and relative standard deviation were 0.01-85.000 µg·L-l, 0.003 µg·L-l, and 3.21%, respectively. The proposed preconcentration procedure was successfully applied to the determination of arsenic ion in a wide range of food samples with different and complex matrixes.

U.S. Food and Drug Administration’s Total Diet Study: How improved analytical methods affect monitoring data

In 2014, the U.S. Food and Drug Administration’s (FDA) Total Diet Study (TDS) began updating the digestion/extraction and the determinative methods for nutrient and toxic elements. The analytical methods for iodine, manganese, and selenium were all updated to inductively-coupled plasma mass spectrometry (ICP–MS) from colorimetric determination, inductively-coupled plasma atomic emission mass spectrometry (ICP–AES), and hydride generation atomic absorption spectrometry (HGAAS), respectively. With updates in digestion/extraction and determinative methods, new limits of detection (LODs) and limits of quantitation (LOQs) were determined. The changes in methods for iodine, manganese, and selenium analysis were evaluated by determining the proportion of results above the LOQ, below the LOD (non-detects or NDs), and between the LOD and LOQ (trace values), in data generated before and after the changes. Selenium showed little change in the proportion of NDs, higher proportions of trace values, and lower proportions of results above the LOQ. Iodine and manganese had lower proportions of NDs and trace values and higher proportions of results above the LOQ. Updating methods can have various effects on data and potentially how data are utilized. These results indicate that these new methods are an improvement on the old methods and validate the changes made to the methodology.

Formation of functionalized silica-based nanoparticles and their application for extraction and determination of Hg (II) ion in fish samples

An isonicotinic acid hydrazide (INAH) chemically modified fumed silica, as a novel adsorbent, was designed for the preconcentration and determination of Hg (II) ions in fish samples via the solid phase extraction followed by the hydride generation atomic absorption spectrometry (HG-AAS). In this work, the efficiency of the synthesized adsorbent was investigated to determine its ability for the extraction of the Hg (II) ions from the aqueous solutions. The extraction efficiency was investigated by optimizing of different experimental conditions, such as pH, sample volume, flow rate, adsorbent dosage, and eluent type. Under the optimal conditions, a linear calibration curve for the solid phase extraction method was obtained in the range of between 0.12 and 16.5 μg L−1. The obtained detection limit and preconcentration factor were 0.018 μg L−1 and 25, respectively (RSD > 3%). The proposed optimized method was successfully applied to fish samples.

Determination of arsenic, copper and lead in the water of villages of Chalkidiki, Greece

Arsenic, copper and lead metals are serious contaminants for human health. These metals are all toxic above a minimum concentration. In the present study twenty two water samples (eleven sites - non and acidified) from villages Nea Silata, Nea Triglia, Eleochoria, Nea Plagia, Tenedos and Sozopolis, municipality of Poligiros, prefecture of Chalkidiki, Greece were collected for quantitatively determination of arsenic, copper-65 and lead-208 by Hydride Generation - Atomic Absorption Spectroscopy (HG-AAS) and Inductively Coupled Plasma - Mass Spectrometry (ICP-MS). The kinds of water were categorized as: drinking water, irrigation water and geothermal water. The results exhibited normal levels for all the three heavy metals under examination apart from geothermal water at Eleochoria village and in some cases for irrigation water at Nea Triglia and Tenedos villages for which the levels of arsenic were a little elevated. Drinking water samples from Nea Plagia and Nea Triglia villages showed lower heavy metal levels than the official Maximum Contaminant Levels (MCL) and therefore the water at these villages is considered to be potable.