HR-CS GF AAS Research Articles

Analysis of nanomaterials based on indium and zinc oxides by high resolution continuum source atomic absorption spectrometry

The properties of nanostructured materials based on zinc and indium oxides can be modified by adding alloying elements to obtain the necessary electrical or optical properties. For example, the specificity of the chemical properties of ZnO and In 2 O 3 for the determination of toxic gases is achieved by immobilizing Au, Ag, etc. nanoparticles on their surface. Control of the material composition plays an important role in determining the dependence between the dopant content and functional properties of the materials. The study is aimed at the development of a methodical approach to the multi-element determination of catalytic dopants (Ag, Au) and matrix elements in nanostructured tin and indium oxides atomic using continuum source graphite furnace atomic absorption spectrometry (HR CS GFAAS). The matrix of the synthesized nanostructured materials (NM) is formed by the corresponding oxide with possible oxygen deficiency occurred due to the temperature conditions of synthesis (300 – 700°C), and the content of additives (Ag, Au) being varied from 1 to 3 % wt. Pyrolysis and atomization conditions for sequential multi-element atomic absorption analysis are determined. The most suitable pyrolysis temperatures upon HR CS GFAAS determinations of Ag and Au (for both In and Zn oxides), are 1000, 1600, 1200 and 900°C, respectively. The most suitable atomization temperatures for ETAA-NIS determinations of Ag, Au (for indium oxide based NM, Au (for zinc oxide based NM), In, and Zn are 1800, 2200, 2100, 2200, and 1500°C, respectively. The accuracy of analyte determination reached 1 – 4 % rel. The correctness of the results was proved by inductively coupled plasma mass spectrometry. The developed method provides control of the composition of synthesized nanostructured materials for their more efficient use in photovoltaics, as well as in production of chemical sensors for detection of harmful compounds like CO, NO 2 , NH 3 .

Simultaneous Determination of Chromium and Iron in Powdered Milk Using High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry

This work proposes the simultaneous determination of chromium and iron in powdered milk samples using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) and sample digestion in microwave oven using nitric acid and hydrogen peroxide. The method was established using the primary line (357.869 nm) for chromium and the adjacent secondary line (358.120 nm) for iron while employing aluminum as the chemical modifier. The absorbance signals were measured by peak area using three pixels for both elements. Chromium and iron can be determined in powdered milk samples by the external calibration technique with limits of quantification of 28 ng g−1 for chromium and 19 μg g−1 for iron. The precision was evaluated by using a milk sample with chromium and iron concentrations of 0.76 μg g−1 and 151.3 μg g−1, respectively. The results expressed as relative standard deviation (n = 10) were 2.6% for iron and 3.9% for chromium. The method accuracy was confirmed by the analysis of a milk sample by a comparison of results obtained by the proposed method and those found by employing inductively coupled plasma mass spectrometry (ICP-MS). Five samples were analyzed, and the analyte concentrations found varied from 408 to 805 ng g−1 for chromium. Among the five samples, three had an iron concentration lower than 19 μg g−1 and in the other two samples, the iron concentrations varied from 151 to 199 μg g−1.

Effective and High-Throughput Analytical Methodology for the Determination of Lead and Cadmium in Water Samples by Disposable Pipette Extraction Coupled with High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry (HR-CS GF AAS)

A new procedure for the preconcentration of trace amounts of free Pb and Cd by disposable pipette extraction (DPX) is proposed herein. Recycled cork is used as a biosorbent and the procedure is completely free of organic solvents. The cork was reduced to a powder and characterized by scanning electron microscopy. Several parameters that influence the preconcentration of Pb and Cd with DPX-cork, such as the sample pH, number of extraction cycles, biosorbent mass, and percentage of acid in the desorption step, were studied. The tolerance of DPX-cork with respect to 10 potential interfering ions was also evaluated. Coupled with the high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) technique, the sample preparation method allowed the analytical limits required for quality control (according to the permitted limits established by legislation) to be obtained. The limits of detection for the extraction of a 3.5-mL water sample were 200 ng L−1 for Pb and 100 ng L−1 for Cd. The relative standard deviations were around 7.5% for Pb and 8.0% for Cd. The optimized method was successfully applied to the determination of Cd and Pb in two certified reference materials (water and wastewater) and five water samples (collected from a mangrove, a creek, and the sea).

Simultaneous determination of Co, Fe, Ni and K with HR CS GFAAS

In this work, a method for simultaneous determination of four different elements, Co, Fe, Ni and K with high resolution continuum source graphite furnace atomic absorption spectrometry was developed. For this purpose less sensitive lines of four elements were selected (344.364 nm for Co, 344.388 nm for Fe, 344.626 nm for Ni and 344.641 nm for K). The pyrolysis and atomization temperatures were of 1000 and 2000 °C, respectively, and no chemical modifier was necessary. Calibration against aqueous standards lead to good agreement between certified or informed values and the determined values, at a statistical confidence level of 95%; recovery tests were performed for real samples, resulting in recoveries ranging from 90 to 110%. Limit of quantification for 0.050 mg L−1 Co, 0.173 mg L−1 Fe, 0.267 mg L−1 Ni and 0.629 mg L−1 K have been obtained, which are adequate for the purpose.

Determination of arsenic in agricultural soil samples using High-resolution continuum source graphite furnace atomic absorption spectrometry and direct solid sample analysis

Soils around coal-fired thermal power plants based on coal combustion can present high concentrations of arsenic. This fact has a direct effect on the food chain. Arsenic can be absorbed by plants and vegetables through the soil, which will then serve as food for different animals, spreading the contamination. A method has been developed using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS) for direct determination of arsenic in solid soil samples. Different chemical modifiers were tested to suppress the matrix effects observed. Among them, the modifier that showed the best results was the Zr, used as a permanent modifier. The optimized pyrolysis and atomization temperatures were 1000 °C and 2200 °C, respectively. A calibration curve was established using aqueous standard solutions which was linear up to 16 ng of arsenic. The characteristic mass and limit of detection were 22 pg and 73 pg As, respectively. The accuracy of the method was verified using two certified reference materials and comparison with results obtained for samples after microwave-assisted digestion. Eleven soil samples were collected around the power plant Complex Jorge Lacerda–Tractebel Suezin, in the south of Santa Catarina, Brazil. The concentration of As ranged from 3.4 mg kg−1 to 9.7 mg kg−1, which is within the limits allowed by Brazilian legislation.

Patterns of toxic metals bioaccumulation in a cross-border freshwater reservoir

In freshwater ecosystems toxic metals can follow different routes of bioaccumulation in the organisms' body mass, routes that are similar to electronic circuits, but far more complex due to their hierarchy levels. Reservoirs located on river courses have positive impacts on economic and social development because they concentrate large water volumes used for electrical energy production, water supply, irrigation, industry, aquaculture, providing ecosystems for migratory birds and aquatic species. The aim of the study was to assess the contamination with copper (Cu), cadmium (Cd), lead (Pb), chromium (Cr) and nickel (Ni) of a cross-border reservoir located on River Prut (border between Romania and Republic of Moldova) in a temperate climate zone. Several aspects were considered: seasonal variation of water parameters and toxic metals, bioconcentration in eight fish species and transfer from prey to predator through the food chain, bioaccumulation by two freshwater molluscs separated in size groups and their role as bioindicators of toxic metals pollution. Metals concentrations were measured with an atomic absorption spectrometer (HR-CS GF-AAS). Cadmium, lead, nickel and chromium concentrations limits in water samples were below the detection limits (0.005 μg L−1Cd, 0.013 μg L−1Pb and 0.011 μg L−1Cr) during the monitoring period, suggesting that anthropogenic contamination was insignificant in the studied ecosystem. Fish liver and kidney had specific selectivity for copper (0.9–55.56 μg g−1) and cadmium (0.097–1.031 μg g−1) in case of pike-perch and bighead carp. The separation of molluscs in size groups did not prove that toxic metals increase in concentration with the organism age.

Multivariate optimization of ultrasound-assisted extraction using Doehlert matrix for simultaneous determination of Fe and Ni in vegetable oils by high-resolution continuum source graphite furnace atomic absorption spectrometry

A method for simultaneous determination of Fe (232.036 nm) and Ni (232.195 nm) in vegetable oil samples by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) after an acid extraction of the analytes is proposed. In the extraction step, hydrochloric, nitric and acetic acid solutions were tested. The optimization of the procedure was performed by applying Doehlert matrix, and multiple response was used for simultaneous evaluation of the performance of the extraction. The optimum conditions were: extraction time of 17 min, extraction temperature of 39 °C and sonication amplitude of 42%, employing 0.5 mol L−1 HCl as the extracting solvent. The limits of quantification were 60 and 160 ng g−1 for Fe and Ni, respectively. The method was applied to the analysis of vegetable oil samples and the results were compared with a method employing inductively coupled plasma optical emission spectrometry (ICP OES).

Low cost adsorbents in ultrasound-assisted dispersive micro solid-phase extraction for simultaneous determination of indium and nickel by high-resolution continuum source graphite furnace atomic absorption spectrometry in soils and sediments

In this study, the analytical potential of USA DMSPE with bentonite clay as a low cost adsorbent combined with HR-CS GF AAS in the simultaneous determination of In and Ni was evaluated.

Sequential determination of gallium, indium, and thallium in environmental samples after preconcentration on halloysite nanotubes using ultrasound-assisted dispersive micro solid-phase extraction

A preconcentration procedure for gallium, indium, and thallium using HNTs was developed prior to their sequential determination by HR-CS GFAAS.

Determination of gold and cobalt dopants in advanced materials based on tin oxide by slurry sampling high-resolution continuum source graphite furnace atomic absorption spectrometry

A novel approach is developed for the determination of Co and Au dopants in advanced materials based on tin oxide using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR CS GFAAS) with direct slurry sampling. Sodium carboxylmethylcellulose (Na-CMC) is an effective stabilizer for diluted suspensions. Use Na-CMC allows to transfer the analytes into graphite furnace completely and reproducibly. The relative standard deviation obtained by HR CS GFAAS was not higher than 4%. Accuracy was proven by means inductively coupled plasma mass spectrometry (ICP-MS) in solutions after decomposition as a comparative technique. To determine Au and Co in the volume of SnO2, the acid decomposition conditions (HCl, HF) of the samples were suggested by means of an autoclave in a microwave oven.

Simultaneous determination of rhodium and ruthenium by high-resolution continuum source graphite furnace atomic absorption spectrometry

In the present paper a fast, simple and sensitive analytical method for simultaneous determination of rhodium and ruthenium by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS) was developed. Among six pairs of absorption atomic lines of Rh and Ru, which are close enough to enable their simultaneous detection, two pairs were selected for further studies. Best results were obtained for measurements of the resonance line of rhodium at 343.489nm and the adjacent secondary line of ruthenium at 343.674nm (23% intensity of this line). For evaluated lines, the absorbance values were obtained using three pixels. The pyrolysis and atomization temperatures were 1200°C and 2600°C, respectively. Under these conditions the limits of detection achieved for Rh and Ru were found to be 1.0μgL−1 and 1.9μgL−1, respectively. The characteristic mass was 12.9pg for Rh and 71.7pg for Ru. Repeatability of the results expressed as a relative standard deviation was typically below 6%.The trueness of the method was confirmed by analysis of the certified reference material – platinum ore (SARM 76). The recovery of Rh and Ru from the platinum ore was 93.0±4.6% and 90.1±2.5%, respectively. The method was successfully applied to the direct simultaneous determination of trace amounts of rhodium and ruthenium in spiked river water, road runoff, and municipal sewage. Separation of interfering matrix on cation exchange resin was required before analysis of road dust and tunnel dust (CW-7) by HR-CS GFAAS.

Determination of Co and Cr in wet animal feeds using direct solid sample analysis by HR-CS GF AAS

The present study proposes the determination of Cr and Co in wet animal feeds for employing direct solid sample analysis (SS) and high resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). For determination of Cr and Co, the analytical lines 357.8687nm and 240.7254nm were used, respectively. The pyrolysis temperatures were 1500 and 1400°C and atomization temperatures were 2500 and 2400°C for Cr and Co, respectively. The limits of quantification (LoQ) obtained for Cr was 0.03μgg−1 and 0.17μgg−1 for Co. The characteristic masses (m0) also obtained were 2.2pg for Cr and 2.9pg for Co. The accuracy of the proposed methods was performed by analysis of standard reference materials (SRM) of tomato leaves (NIST 1573), bovine muscle powder (NIST 8414) and apple leaves (NIST 1515) for Cr and bovine liver (NIST 1577b) for Co. The trueness obtained were between 102±9 and 116±7% for Cr and 94±8% for Co for analyzed of the SRM. Precision, expressed as relative standard deviation (RSD), was better than 8.7% for Cr and 8.3% for Co (n=5). Thirteen wet animal feed samples for dogs and cats were analyzed. The concentrations values found for Cr in the samples ranged from 0.17±0.01 to 0.59±0.06μgg−1 with an average of 0.36±0.13μgg−1 (n=13). On the other hand, the obtained concentrations for Co ranged between <0.18 and 12.57±1.11μgg−1, with an average of 5.92±3.19μg. The optimized analytical methods were simple, fast, efficient, precise and accurate for determination of Cr and Co in wet animal feeds for cats and dogs by HR-CS SS-GF AAS. Additional advantage of the method was no dissolution of the samples, no use of harmful reagents and consequently no generation of residues, besides the use of an effective analytical technique that allows optimization of fast and reliable screening procedures.

Investigation of chemical modifiers for the determination of cadmium and chromium in fish oil and lipoid matrices using HR-CS GF AAS and a simple ‘dilute-and-shoot’ approach

This work presents simple and reliable methods for the determination of Cd and Cr in fish oil and lipoid samples by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). Only a simple dilution using 1-propanol was adopted as sample preparation for the determination of Cd and Cr in order to reduce the high viscosity of the lipoid samples. Pt was employed as permanent chemical modifier and Pd was used as chemical modifier in solution, added over the sample for the determination of Cd for a better performance and sensitivity. Cr was determined without a chemical modifier. The accuracy of the proposed methods was evaluated by comparison with microwave-assisted digested samples and determination by HR-CS GF AAS, showing good agreement between 2% and 13% for both elements without statistical difference (confidence interval of 95%). The limits of detection for Cd and Cr were 0.5pg and 7pg, respectively, corresponding to 0.15ngg−1 and 2ngg−1, respectively. The developed methods can be described as clean, fast and accurate, which did not require any sample pre-treatment stages, such as digestion or matrix oxidation, and could be extended to different lipoid matrices, demonstrating their robustness.

Alternative method for chromium determination in pharmaceutical drugs by HR-CS GF AAS and direct analysis of solid samples

High-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) was used to develop an analytical method for chromium determination in pharmaceutical drugs through direct analysis of solid samples. The limit of detection and quantification were, respectively, 2.9μgkg−1 and 9.7μgkg−1 and the characteristic mass was 2.0pg. Eighteen pharmaceutical drugs and three excipients were analyzed. The encapsulated samples were opened and only its powder content was analyzed; the tablet samples were grinded before the analysis. The results obtained from the direct analysis of the solid samples were in agreement with those found after total digestion of samples using a closed-vessel microwave oven device, with a confidence level of 95%. The Cr concentration obtained for the different capsules and tablets investigated varied between 0.05 and 1.92mgkg−1. The proposed method is fast, reliable and simple for routine pharmaceutical analysis.

Toxic metals in tissues of fishes from the Black Sea and associated human health risk exposure.

The anthropogenic activities in the Black Sea area are responsible for toxic metal contamination of sea food products. In this study, several toxic metals: cadmium, lead, nickel, chromium, and copper were quantified in different tissues (digestive tract, muscle, skeleton, skin) of nine fish species (Neogobius melanostomus, Belone belone, Solea solea, Trachurus mediterraneus ponticus, Sardina pilchardus, Engraulis encrasicolus, Pomatomus saltatrix, Sprattus sprattus, Scorpaena porcus) by using atomic absorption spectrometer with a high-resolution continuum source and graphite furnace technique (HR-CS GF-AAS), and the risk of fish meat consumption by the young human population was evaluated. These metals are used in high amounts in industries located near the coastline such as shipyard construction and industrial plants. Toxic metal accumulation depends on fish feeding behavior, abiotic conditions, metal chemistry, and animal physiology. For instance, cadmium was measured in the muscle of the investigated species and average values of 0.0008-0.0338mgkg-1 were obtained. The lowest average value of this metal was measured at benthic species N. melanostomus and the highest at the pelagic predator T. mediterraneus ponticus. Generally, the highest metal concentration was measured in the digestive tract that has the role of biofilter for these contaminants. The risk of contamination is significantly reduced by avoiding the consumption of certain fish tissues (digestive tract and skin for copper and skeleton for nickel). An estimation of the dietary metal intake to young consumers was realized for each of the studied species of fish from Romanian, Bulgarian, and Turkish waters, during the period 2001-2014 in order to evaluate the risks of chronic exposure in time due to metal toxicity. This estimation is important for the prevention of chronic exposure due to metal toxicity. Food exposure to studied metals showed a negative trend for Romania, Turkey, and Bulgaria based on the data provided by this study. The young consumers were highly exposed to these elements during the 2001-2006 period as proven by the results from this study.

Direct mercury determination in blood and urine by means of high-resolution continuum source graphite furnace atomic absorption spectrometry using gold nanoparticles as a chemical modifier

The use of Au nanoparticles as a chemical modifier permits the direct Hg determination in urine and blood samples by HR CS GFAAS.

Development of analytical methods for the determination of copper and manganese in infant formula using high resolution continuum source graphite furnace atomic absorption spectrometry and direct solid sample analysis

Two fast, simple and reliable methods for the determination of Cu and Mn in infant formula were developed by HR-CS GF AAS.

A novel extraction-based procedure for the determination of cadmium in marine macro-algae using HR-CS GF AAS

This work proposes a simple method for the determination of Cd in macro-algae by high-resolution continuum source graphite furnace atomic absorption spectrometry.

Determination of heavy metals in cigarettes using high-resolution continuum source graphite furnace atomic absorption spectrometry

Quantitative determination of toxic metals in tobacco, smoke, ash and butts of cigarettes using HR-CS GFAAS.

Direct Determination of Trace Elements in Meat Samples via High-Resolution Graphite Furnace Atomic Absorption Spectrometry

This work presents a direct and straightforward approach for the determination of trace elements in fish muscle, oyster, and bovine liver via direct solid sample analysis (SS) using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). The preliminary studies revealed the presence of spectral interferences at the analytical line of Ni at 231.096 nm, which could be corrected subtracting the spectrum of SiO and PO from the sample spectra using least-squares background correction. Moreover, all meat samples were proven homogeneous according to the homogeneity factor (H e) (all values were <10 mg½). Pyrolysis (Tp) and atomization (Ta) temperatures were studied and optimized as 800 °C (Tp) and 2500 °C (Ta) for Mn, 700 °C (Tp) and 2600 °C (Ta) for Ni, and 600 °C (Tp) and 2500 °C (Ta) for Rb. Calibration against aqueous standards was proven feasible for Mn determination, whereas Ni and Rb required calibration against solid standards for their quantification. The detection limits achieved were demonstrated adequate for application to food analysis (0.005 μg g−1 for Mn, 0.002 μg g−1 for Ni, and 0.1 μg g−1 for Rb). The developed method was successfully applied for the elemental analysis of fish muscle, oyster, and bovine liver and three certified reference materials, demonstrating good agreement with the certified values and with the reference technique at a 95 % statistical confidence level.