Continuum Source Atomic Absorption Spectrometer Research Articles

Trace element bioaccumulation in the plumage of common blackbirds (Turdus merula Linnaeus, 1758) from Agigea, Romania

The purpose of this research was to establish the baseline concentrations of thirteen trace elements (Cd, Co, Cr, Cu, Ni, Pb, Fe, Mg, Na, K, Sr, Ca, and Zn) in feathers of the common blackbird Turdus merula (n=9) at the Natura 2000 site “Marine Dunes from Agigea” (ROSCI0073). Both remiges and rectrices were pooled, and the quantification of trace elements was accomplished using two spectrometry analysis methods: high-resolution continuum source atomic absorption spectrometer with a graphite furnace (HR-CS GF-AAS) and flame atomic absorption spectrometer (FL-AAS). The concentration of Ca was the highest of the thirteen trace elements, registering at 209.9146±192.4098 µg·g-1 w.w., while Cd had the lowest concentration levels in feathers, 0.0243±0.0158 µg·g-1 w.w., respectively. However, the results obtained were significantly lower than those in the relevant literature. These findings suggest that the bioavailability of the analysed trace elements is minimal in our study area. Thus, it is imperative to conduct further research on the impact of these trace elements' accumulation and effects on avifauna in the Natura 2000 site “Marine Dunes from Agigea”.

High-resolution continuum source atomic absorption spectrometry: a review of current applications

Atomic absorption spectrometry (AAS) is one of the most widely used and available methods for analysis of substances and materials. It allows one to determine about 70 elements from the periodic table and is characterized by rapidity, high accuracy and sensitivity, as well as simplicity of analytical techniques. A feature of AAS is simultaneous determination of only one element due to the use of a measurement design with a line source (hollow-cathode lamps, high-frequency electrodeless lamps, optical quantum generators, etc.). To make AAS more competitive, the first commercially available continuum source atomic absorption spectrometer was designed in 2004. Unique analytical capabilities of the new instruments found application first of all in the analysis of food, pharmaceuticals, waste and drinking water, oil and petrochemicals, biological objects, etc. This review covers publications on the application of continuum source AAS in analytical chemistry and provides a development outlook of the method.

Assessment of Ecologic Quality in Terms of Heavy Metal Concentrations in Sediment and Fish on Sakarya River and Dam Lakes, Turkey

ABSTRACTSakarya River with a length of 824 km is one of the most important lothic ecosystems of Turkey. Sarıyar, Gökçekaya and Yenice Dams were constructed on the Sararya River for the purpose of electric supply and utility water for agricultural and fishery activities. In this study, sediment samples were collected from 14 stations selected on areas seasonally (2015–2016). Also, cyprinidae species (Carassius gibelio (Bloch, 1782), Capoeta baliki Turan, Kottelat, Ekmekçi & Imamoglu 2006) were caught from Dam Lakes and Sakarya River. Cr, Ni, Cu, Zn, Pb levels in sediment samples and in tissues (liver, gill and muscle) of fish were analyzed in samples by Analytic Jena ContrAA 700 (high-resolution continuum source atomic absorption spectrometer). The data observed were evaluated with national and international quality criteria. According to the data in the study results, heavy metal accumulations in the gill and liver of fish were determined higher than muscle. Zn levels in muscle of C. gibelio caught from Yenice Dam Lake were higher than the permissible limit stated by Turkish legislation and FAO. Also, Cr and Ni levels in sediment samples especially during rainy seasons were higher to dry seasons and Cr and Ni levels were detected higher than sediment quality guidelines.

Mineral Content of Various Portuguese Breads: Characterization, Dietary Intake, and Discriminant Analysis.

The chemical composition and daily mineral intake (DMI) of six macro (calcium, magnesium, sodium, potassium, phosphorous, and chloride) and four microminerals (copper, iron, manganese, and zinc) were determined in four types of Portuguese breads (white wheat, maize, wheat/maize, and maize/rye breads). Samples were processed with microwave assisted digestion and mineral composition was determined with a high-resolution continuum-source atomic absorption spectrometer with flame and graphite furnace. Bread contributes to an equilibrated diet since it is rich in several minerals (0.21 mg/100 g of copper in wheat bread to 537 mg/100 g of sodium in maize/rye bread). Maize/rye bread presented the highest content of all minerals (except phosphorous and chloride), while the lowest levels were mainly found in wheat bread. Median sodium concentrations (422–537 mg/100 g) represented more than 28% of the recommended daily allowance, being in close range of the maximum Portuguese limit (550 mg/100 g). Maize/rye bread exhibited the highest DMI of manganese (181%), sodium (36%), magnesium (32%), copper (32%), zinc (24%), iron (22%), potassium (20%), and calcium (3.0%). A Principal Component Analysis (PCA) model based on the mineral content allowed the differentiation among white wheat, maize, and maize/rye bread. Zinc, magnesium, manganese, iron, phosphorus, potassium, copper, and calcium proved to be good chemical markers to differentiate bread compositions.

Determination of heavy metals in olive fruits as an indicator of environmental pollution

ABSTRACT Characterization of olive fruits according to their heavy metal composition was carried out with a chemometric approach. The concentrations of Pb, Cd, Cr, Mn, Fe, Ni and Co in the olive samples were determined by high-resolution continuum source atomic absorption spectrometer (HR-CS AAS). Heavy metal contamination in twenty-three olive samples collected from different regions (industrialized and non-industrialized) of Hatay province in Turkey was evaluated. Analytical performance and reliability of the method were checked by validation parameters. The results demonstrated that the mean content of heavy metals in the olive samples were ranged between 0.046 and 17.229 mg kg−1. The analytical data was examined by principal component analysis (PCA) and cluster analysis (CA) for the classification studies. The olive samples were classified into three groups reflecting the groups of unpolluted, industrial polluted and non-industrial polluted stations. This model can be a useful tool for the olive industry to emphasize product quality and naturalness.

Application of Solid Sampling for the Determination of Total Fluorine in Fish and Seafood by High-Resolution Continuum Source Graphite Furnace Molecular Absorption Spectrometry

ABSTRACTTotal fluorine concentrations in some fish species and seafood such as mussels, squid (calamary), and shrimp were determined using the molecular absorption of calcium monofluoride (CaF) generated in a graphite furnace using a high-resolution continuum source atomic absorption spectrometer and direct solid sampling. The fish fillets and seafood were dried at 110°C, minced finely, put on the platform using masses less than 1.2 mg, and introduced to the graphite furnace with 20 µg of calcium by a solid sampling accessory. The effects of CaF wavelength, graphite furnace program, amount of sample introduced to the furnace, the use of modifier on the determination of fluorine were investigated and optimized. The absolute limit of detection and characteristic mass of the method were 0.28 and 0.14 ng of fluorine, respectively. By applying the optimized parameters, the concentrations of fluorine in various fish species and seafood were determined.

Method development for the determination of chlorine by high-resolution graphite furnace molecular absorption spectrometry via GaCl

In this study, a method was developed for the determination of chlorine via molecular absorption of GaCl at 249.060 nm generated in a graphite furnace of a high-resolution continuum source atomic absorption spectrometer. For this purpose, 25 μg of Ga and standard solutions or samples were mixed on the platform. The optimized pyrolysis and vaporization temperatures were 500 and 1100 °C, respectively, which were uncommonly low compared to other diatomic molecules between chlorine and molecule forming reagents of chlorine and non-metals. The limit of detection for the method was 2.3 ng which was sufficient to determine chlorine in samples to be analyzed in this study as well as in many matrices. The Cl concentration was determined in uncertainty limits of a certified wastewater sample. Finally, Cl concentrations in some milk and mineral water samples were determined using aqueous standards for calibration. The results were compared with those found by analyte addition technique and no significant difference was found.

Determination of silicon in biomass and products of pyrolysis process via high-resolution continuum source atomic absorption spectrometry

Thermochemical processes can convert the biomass into fuels, such as bio-oil. The biomass submitted to pyrolysis process, such as fibers, are generally rich in silicon, an element that can lead to damages in an engine when there is high concentration in a fuel. High-resolution continuum source atomic absorption spectrometry (HR-CS AAS) is an interesting alternative for Si determination in the products and byproducts of the pyrolysis process because, besides the flame (F) and graphite furnace (GF) atomizers, it has enhanced the application of direct analysis of solid samples (SS) within GF. This study aimed the development of methods to determine Si in biomass samples, their products and byproducts using HR-CS AAS. A high-resolution continuum source atomic absorption spectrometer contrAA 700 equipped with F and GF atomizers was used throughout the study. HR-CS F AAS (λ = 251.611nm, 1 detection pixel, N2O/C2H2 flame) was used to evaluate Si content in biomass and ash, after a microwave-assisted acid digestion with HNO3 and HF. HR-CS GF AAS (Tpyr = 1400°C, Tatom = 2650°C) has evaluated Si in pyrolysis water and bio-oil at 251.611nm, and in peach pit biomass and ash at 221.174nm using SS, both wavelengths with 1 detection pixel. Rhodium (300μg) was applied as permanent modifier and 10μgPd + 6μg Mg were pipetted onto the standards/samples at each analysis. Three different biomass samples were studied: palm tree fiber, coconut fiber and peach pit, and three certified reference materials (CRM) were used to verify the accuracy of the methods. The figures of merit were LOD 0.09–20mgkg–1, and LOQ 0.3–20mgkg–1, considering all the methods. There were no significant differences between the CRM certified values and the determined ones, using a Student t-test with a confidence interval of 95% (n = 5). Si concentration ranged from 0.11–0.92% mm–1, 1.1–1.7mgkg–1, 3.3–13mgkg–1, and 0.41–1.4%mm–1, in biomass, bio-oil, pyrolysis water and ash, respectively. Si remained mostly in the ash, leading to a mass fraction of up to 103%, even when the Si loss is not considered. Silicon concentration in bio-oil was below 1.7mgkg–1, which is suitable for its application as a fuel. The developed methods using HR-CS AAS are suitable for Si determination in biomass, bio-oil, pyrolysis water, and ash. The application of bio-oil as an alternative fuel would be possible evaluating its Si content due to its low levels. The mass balance for Si has proved to be an important tool in order to evaluate the correct disposal of pyrolysis process byproducts.

Speciation of chromium in bread and breakfast cereals

Bread and breakfast cereals are a major constituents of the human diet, yet their Cr(VI) content is not known. Chromium(VI) was determined in these products by high resolution continuum source atomic absorption spectrometer (HR-CS AAS) after leaching Cr(VI) with 0.10molL−1 Na2CO3.The results showed that 33–73% of total Cr (58.17±5.12μgkg−1–156.1±6.66μgkg−1) in bread exist as Cr(VI) and the highest total Cr content was found in brown bread. It was shown that Cr(III) is oxidized to Cr(VI) during toasting of bread.Chromium(VI) content in breakfast cereals ranged between 20.4±4μgkg−1 and 470.4±68μgkg−1. Therefore, it can be concluded that bread and breakfast cereals contains Cr(VI) which does not exceed maximum acceptable concentration (MAC) of 0.003mgkg−1bw−1day−1 through daily consumption of half a bowl (65g) of breakfast cereal and four slices of toasted (122g) or untoasted bread (160g).

Determination of fluorine in Turkish wines by molecular absorbance of CaF using a high resolution continuum source atomic absorption spectrometer

Fluorine contents of different types of wines produced in Turkey were determined by the molecular absorption of calcium mono-fluoride (CaF) using a high resolution continuum source graphite furnace atomic absorption spectrometer (HR-CS GFAAS). For this purpose, 2000 μg mL−1 of calcium was co-injected to the graphite furnace with diluted wine samples. In order to increase the sensitivities and reduce the limit of detection (LOD) and characteristic mass, summation of the absorbances for CaF at 606.440 nm and 606.231 nm were evaluated. Graphite furnace program was optimized for best accuracy and 700 °C for pyrolysis, 2250 °C for molecule forming temperature was selected. Quantification was made by linear calibration, standard addition technique by HR-CS-AAS and the results were also compared with ISE method and no significant difference was found. The range of F contents for 20 red and white wine samples varies between LOD and 0.38 mg L−1. The limit of detection and characteristic mass of the method were 0.18 and 0.058 ng of F, respectively which are appropriate to detect the fluorine concentrations in most of the wine samples. The method is simple, fast, accurate and sensitive.

Direct and Sequential Determination of Six Metal Elements in Cooking Wine by HR-CS GFAAS

The aim of this work was to develop a sensitive, simple and direct procedure for the determination of Cu, Cd, Cr, Pb, Mn and Al in the cooking wine by HR-CS GFAAS with a minimum sample pre-treatment. The analyses of the six metal elements were conducted using a high resolution continuum source atomic absorption spectrometer. The cooking wine as sample was just diluted in ultrapure water with 1.0% (v/v) HNO3and the analytical lines of the six metal elements were selected scientifically. The correlation coefficients better than 0.99 were obtained and the limits of detection were 0.86, 0.08, 0.28, 0.81, 0.61 and 1.54 μg/L for Cu, Cd, Cr, Pb, Mn and Al, respectively. Recoveries varied form 96.1% to 105.7%. The proposed method was applied to the determination of the six metal elements in the cooking wine and the results showed that the mass concentrations of Cu, Cd, Cr, Pb, Mn and Al were 2.10, 0.177, 7.98, 1.86, 22.3 and 217.2 μg/L, respectively. There was a good agreement between the proposed method and the microwave digestion-HR-CS GFAAS method, and F-test and t-test at 95% of confidence had no significant difference. Therefore, the proposed method was accurate and stable with a high practical value. It provided scientific basis for quality control in food industries.

Determination of fluorine in milk and water via molecular absorption of barium monofluoride by high-resolution continuum source atomic absorption spectrometer

This study describes the determination of fluorine evaluating the molecular absorption of barium monofluoride (BaF) at the rotational lines of 495.088 and 495.263nm simultaneously using a high-resolution continuum source electrothermal atomic absorption spectrometer. Upon pipetting of samples together with Ba as its nitrate, BaF was generated in the gas-phase of the atomizer. All experiments were performed using pyrolytically coated graphite tubes/platforms and applying 900°C for pyrolysis and 2200°C for vaporization. In the presence of 50μg of Ba, a perfect linearity up to 0.1μg of F was maintained. The limit of detection and characteristic mass of the method were 0.105ng and 0.055ng of F, respectively. The F concentration of a standard waste water sample was found in the uncertainty limits of its certified value as well as spike additions were quantitatively recovered. Finally, F concentrations in various water and milk samples sold in markets were determined.

Quantitative determination of sulfur by high-resolution graphite furnace molecular absorption spectrometry

In this paper a new procedure for quantitative determination of sulfur, which is based on the molecular absorption of tin sulfide at a wavelength of 271.578nm, is described. For that purpose a commercially available high-resolution continuum source atomic absorption spectrometer with a transversely heated graphite tube furnace is used. The temperature program is optimized and the measurements are accomplished with a Zr-coated graphite tube without platform.A limit of detection of 0.16ngS absolute is achieved. Furthermore, the accuracy of the procedure is verified by the recovery rate of both an inorganic and an organic compound. Several water samples from rivers and ponds, three mineral waters with a concentration range from 3 to 370mg/LS, and one certified reference material are analyzed, too. The results are consistent with the measured values of ion chromatography and gravimetric analysis. The non-spectral interelement effect of Ni has displayed a signal loss. With a 1:1 relation of metal to analyte a loss of 11% of the absorption signal has appeared. This effect is very seldom in natural environment, so the procedure is robust and there are no spectral interelement effects. In addition, this procedure is faster and more easy-to-handle than other methods at this point of time, and resulting in the improved limit of detection.

A fast and accurate method for the determination of total and soluble fluorine in toothpaste using high-resolution graphite furnace molecular absorption spectrometry and its comparison with established techniques

A fast and reliable method has been developed for the determination of total and soluble fluorine in toothpaste, important quality control parameters in dentifrices. The method is based on the molecular absorption of gallium mono-fluoride, GaF, using a commercially available high-resolution continuum source atomic absorption spectrometer. Transversely heated platform tubes with zirconium as permanent chemical modifier were used throughout. Before each sample injection, a palladium and zirconium modifier solution and a gallium reagent were deposited onto the graphite platform and thermally pretreated to transform them into their active forms. The samples were only diluted and introduced directly into the graphite tube together with additional gallium reagent. Under these conditions the fluoride was stable up to a pyrolysis temperature of 550 °C, and the optimum vaporization (molecule formation) temperature was 1550 °C. The GaF molecular absorption was measured at 211.248 nm, and the limits of detection and quantification were 5.2 pg and 17 pg, respectively, corresponding to a limit of quantification of about 30 μg g −1 (ppm) F in the original toothpaste. The proposed method was used for the determination of total and soluble fluorine content in toothpaste samples from different manufactures. The samples contained different ionic fluoride species and sodium monofluorophosphate (MFP) with covalently bonded fluorine. The results for total fluorine were compared with those obtained with a modified conventional headspace gas chromatographic procedure. Accuracy and precision of the two procedures were comparable, but the proposed procedure was much less labor-intensive, and about five times faster than the latter one.

Optimization of fluorine determination via the molecular absorption of gallium mono-fluoride in a graphite furnace using a high-resolution continuum source spectrometer

The determination of fluorine using the molecular absorption of gallium mono-fluoride (GaF) at the 211.248 nm rotational line has been optimized using a commercially available high-resolution continuum source atomic absorption spectrometer with a transversely heated graphite tube furnace. The electron excitation spectrum of GaF was generated by adding 500 μg Ga per injection into the graphite tube as molecule forming reagent. Best results were obtained by applying Zr as a permanent modifier and a mixed Pd/Zr modifier, thermally pretreated before each sample injection together with the Ga reagent at 1100 °C. The use of sodium acetate and Ru(III) nitrosyl nitrate as additional modifiers injected together with the sample further improved the performance. This way a maximum pyrolysis temperature of 550 °C could be used, and the optimum molecule forming temperature was 1550 °C. Several drinking water samples, a mineral water sample, and two certified reference materials were analyzed using the standard calibration technique; the absence of potential matrix effects was verified by measuring different dilutions and spiking with known fluorine mass. The results were in good agreement with the certified values and those measured by ion selective electrode; the recovery rate for the spiking experiments was between 97% and 106%. The results show that there was no matrix influence for that kind of samples containing relatively high concentrations of Ca, Mg and chloride, which are known to cause interference in GaF molecule absorption. The limit of detection and the characteristic mass of the method were 5.2 and 7.4 pg F, respectively, and were both about a factor of two better than recently published values.

Investigation of phosphorus atomization using high-resolution continuum source electrothermal atomic absorption spectrometry

The atomization of phosphorus in electrothermal atomic absorption spectrometry has been investigated using a high-resolution continuum source atomic absorption spectrometer and atomization from a graphite platform as well as from a tantalum boat inserted in a graphite tube. A two-step atomization mechanism is proposed for phosphorus, where the first step is a thermal dissociation, resulting in a fast atomization signal early in the atomization stage, and the second step is a slow release of phosphorus atoms from the graphite tube surface following the adsorption of molecular phosphorus at active sites of the graphite surface. Depending on experimental conditions only one of the mechanisms or both might be active. In the absence of a modifier and with atomization from a graphite or tantalum platform the second mechanism appears to be dominant, whereas in the presence of sodium fluoride as a modifier both mechanisms are observed. Intercalation of phosphorus into the graphite platform in the condensed phase has also been observed; this phosphorus, however, appears to be permanently trapped in the structure of the graphite and does not contribute to the absorption signal.

Determination of sulfur by molecular absorption of carbon monosulfide using a high-resolution continuum source absorption spectrometer and an air-acetylene flame

A standard air-acetylene flame, attached to a high-resolution continuum source atomic absorption spectrometer, was used to determine sulfur via measurements of selected rotational lines of carbon monosulfide (CS) formed in the flame. The lines are part of the strong molecular absorption system around 258 nm. Their half-widths in the order of a few picometers are comparable to common atomic lines. The analytical method is characterized by simplicity, rapidity, reliability, and robustness. Potential chemical and spectral interferences were tested using nitric, hydrochloric, perchloric and hydrofluoric acids at concentrations up to 5% (v/v), and solutions of Al, Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, and Pb at concentrations up to 2000 mg L −1. The only serious spectral interference occurred with Pb at concentrations higher than 200 mg L −1, which is due to the formation of lead sulfate in the solution. The limit of detection achieved for sulfur was 2.4 mg L −1, using the CS line at 258.056 nm and a measurement time of 5 s. A linear dynamic range of more than 3 orders of magnitude was obtained. The analytical results were verified by means of standard reference materials, yielding good precision and accuracy.

Determination of cobalt in biological samples by line-source and high-resolution continuum source graphite furnace atomic absorption spectrometry using solid sampling or alkaline treatment

Two procedures for the determination of Co in biological samples by graphite furnace atomic absorption spectrometry (GF AAS) were compared: solid sampling (SS) and alkaline treatment with tetramethylammonium hydroxide (TMAH) using two different instruments for the investigation: a conventional line-source (LS) atomic absorption spectrometer and a prototype high-resolution continuum source atomic absorption spectrometer. For the direct introduction of the solid samples, certified reference materials (CRM) were ground to a particle size ≤50 μm. Alkaline treatment was carried out by placing about 250 mg of the sample in polypropylene flasks, adding 2 mL of 25% m/v tetramethylammonium hydroxide and de-ionized water. Due to its unique capacity of providing a 3-D spectral plot, a high-resolution continuum source (HR-CS) graphite furnace atomic absorption spectrometry was used as a tool to evaluate potential spectral interferences, including background absorption for both sample introduction procedures, revealing that a continuous background preceded the atomic signal for pyrolysis temperatures lower than 700 °C. Molecular absorption bands with pronounced rotational fine structure appeared for atomization temperatures >1800 °C probably as a consequence of the formation of PO. After optimization had been carried out using high resolution continuum source atomic absorption spectrometry, the optimized conditions were adopted also for line-source atomic absorption spectrometry. Six biological certified reference materials were analyzed, with calibration against aqueous standards, resulting in agreement with the certified values (according to the t-test for a 95% confidence level) and in detection limits as low as 5 ng g −1.

Investigation of interferences in the determination of thallium in marine sediment reference materials using high-resolution continuum-source atomic absorption spectrometry and electrothermal atomization

A high-resolution continuum-source atomic absorption spectrometer with a xenon short-arc lamp as the radiation source, a compact double echelle monochromator with a focal length of 302 mm and a spectral resolution of λ/Δλ≈110 000, and a UV-sensitive charged-coupled device (CCD) array detector was used to investigate the spectral interferences found with a conventional line-source atomic absorption spectrometer in the determination of thallium in marine sediment reference materials. A transversely heated graphite furnace was used as the atomizer unit, and the samples were introduced in the form of slurries. A strong iron absorption line at 276.752 nm, which was observed at atomization temperatures >2000 °C in the vicinity of the thallium resonance line at 276.787 nm, could be responsible for some of the interferences observed with low-resolution continuum-source background correction. The outstanding feature at atomization temperatures <2000 °C was the electron excitation spectrum of the gaseous SO 2 molecule that exhibited a pronounced rotational fine structure, and is for sure the main reason for the observed spectral interferences. The molecular structures could be removed completely by subtracting a model spectrum recorded during the atomization of KHSO 4, using a least squares algorithm. The same results, within experimental error, were obtained for thallium in a variety of marine sediment reference materials using ammonium nitrate as a modifier, ruthenium as a permanent modifier in addition to ammonium nitrate, and without a modifier, using aqueous standards for calibration, demonstrating the ruggedness of the method. A characteristic mass of 15–16 pg Tl was obtained, and a limit of detection of 0.02 μg g −1 Tl was calculated from the standard deviation of five repetitive determinations of HISS-1, the sediment with the lowest thallium content.

Continuum source-atomic absorption spectrometry using a two-dimensional charge coupled device

A single element continuum source-atomic absorption spectrometer (CS-AAS) using a two-dimensional charge coupled array detector (2D-CCD) was assembled for use with graphite furnace atomization. The two-dimensional CCD was a split-frame transfer array, was thinned and back-illuminated for high quantum efficiency at approximately 200 nm, and was capable of an 80-Hz frame rate with a read noise of <15 electrons. The transfer of charges from the integrating arrays to the storage arrays took 0.65 ms, less than 4% of the frame period (16.42 ms). The transfer of charges to the storage array was perpendicular to the wavelength axis, eliminating source flicker noise, and was implemented without masking, producing vertical smearing. The smearing was manifested as a continuum background and was corrected using pixels between orders. The two-dimensional array, in conjunction with the high-resolution echelle spectrometer, allowed measurement of absorbance with respect to wavelength and height in the furnace. Computed absorbances were corrected for stray radiation and non-specific background absorption. Detection limits were equal to those for line source AAS, with the exception of As (193.7 nm) and Se (196.0 nm).