High-resolution Continuum Source Graphite Furnace Research Articles

Development of a method for the sequential determination of cadmium and chromium from the same sample aliquot of yerba mate using high-resolution continuum source graphite furnace atomic absorption spectrometry

A simple, fast and sensitive method for the sequential determination of cadmium and chromium from the same sample aliquot of yerba mate and leaves of yerba mate is proposed using high-resolution continuum source graphite furnace atomic absorption spectrometry and direct solid sample analysis. The measures were made using the analytical line at 228.802nm for cadmium and 357.869nm for chromium, and three pixels each for evaluation. The reference material NCS ZC73014 (trace elements in tea) has been analyzed and the results were in agreement with the certified values. A characteristic mass of 0.37pg and 2.4pg was obtained for cadmium and chromium, respectively. The limits of detection were 0.25ng for cadmium and 0.72ng for chromium, and the precision, expressed as relative standard deviation, was around 10%. Thirteen commercial samples and five leave samples were analyzed and the concentration of cadmium varied between 0.28 and 2.06μgg−1 and that of chromium between 0.27 and 2.37μgg−1. The process of infusion preparation resulted in a leaching of around 25% for cadmium and 60% for chromium.

Simultaneous determination of iron and nickel in fluoropolymers by solid sampling high-resolution continuum source graphite furnace atomic absorption spectrometry

This paper reports the development of a method of simultaneous determination of iron and nickel in fluoropolymers by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) with direct solid sampling. In order to carry out simultaneous measurements, both the main resonance line of nickel (232.003nm) and the adjacent secondary line of iron (232.036nm) were monitored in the same spectral window. The proposed method was optimized with a perfluoroalkoxy (PFA) sample and was applied to the determination of iron and nickel in fluorinated ethylene propylene (FEP) and modified polytetrafluoroethylene (PTFE-TFM) samples. Pyrolysis and atomization temperatures, as well as the use of Pd and H2 (during pyrolysis) as chemical modifiers, were carefully investigated. Compromise temperatures for pyrolysis and atomization of both analytes were achieved at 800 and 2300°C, respectively, using only 0.5Lmin−1 H2 as chemical modifier during pyrolysis. Calibration curves were performed with aqueous standards by using a single solution which contained both analytes. Limits of detection were 221 and 9.6ngg−1 for iron and nickel, respectively. Analyte concentrations in all samples ranged from 3.53 to 12.4µgg−1 for iron and from 37 to 78ngg−1 for nickel, with relative standard deviation less than 19%. Accuracy was evaluated by comparing these results with those obtained by inductively coupled plasma mass spectrometry after sample digestion by microwave-induced combustion and no significant statistical difference was observed.

Direct and Simultaneous Determination of Copper and Iron in Flours by Solid Sample Analysis and High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry

In this work, a simple, fast, and robust method was developed for the direct and simultaneous determination of copper and iron in flours using solid sample analysis and high-resolution continuum source graphite furnace atomic absorption spectrometry. The secondary lines at 217.894 and 217.812 nm were used for all simultaneous measurements of copper and iron, respectively. The pyrolysis and atomization temperatures were of 1400 and 2400 °C, respectively, and no chemical modifier was necessary. The slope of calibration curve obtained, using the rice flour certified reference material (NIST 1568a) as solid standard, presented no significant difference when compared with the slope of external calibration curve using aqueous standard, at 95 % confidence level. Under these conditions, the limits of quantification obtained were 0.38 (Cu) and 0.11 (Fe) mg kg−1, respectively. The relative standard deviations (RSD) varied from 0.5 to 14 % for copper and from 4.9 to 17 % for iron. The method accuracy was confirmed by analysis of two certified reference materials, rice flour NIST 1568a and wheat flour NIST 1567a, and the results were in agreement with the certified values, at 95 % confidence level. The proposed method was applied for the analysis of flour samples (corn, wheat, and white bean), both of conventional and organic cultivation. The concentration values varied in the range of 0.6–5.9 mg kg−1 for copper and of 2.6–50.4 mg kg−1 for iron. The iron concentrations in all samples analyzed were not in agreement with the value established by the Brazilian legislation, which is of 42 mg of iron per kilogram of flour.

Fast and direct screening of copper in micro-volumes of distilled alcoholic beverages by high-resolution continuum source graphite furnace atomic absorption spectrometry

HR-CS-GFAAS methods were developed for the fast determination of Cu in domestic and commercially available Hungarian distilled alcoholic beverages (called pálinka), in order to decide if their Cu content exceeds the permissible limit, as legislated by the WHO. Some microliters of samples were directly dispensed into the atomizer. Graphite furnace heating programs, effects/amounts of the Pd modifier, alternative wavelengths (e.g., Cu I 249.2146nm), external calibration and internal standardization methods were studied. Applying a fast graphite furnace heating program without any chemical modifier, the Cu content of a sample could be quantitated within 1.5min. The detection limit of the method is 0.03mg/L. Calibration curves are linear up to 10–15mg/L Cu. Spike-recoveries ranged from 89% to 119% with an average of 100.9±8.5%. Internal calibration could be applied with the assistance of Cr, Fe, and/or Rh standards. The accuracy of the GFAAS results was verified by TXRF analyses.

Separation and preconcentration of platinum-group metals from spent autocatalysts solutions using a hetero-polymeric S, N-containing sorbent and determination by high-resolution continuum source graphite furnace atomic absorption spectrometry

This paper describes the potential of high-resolution continuum source graphite furnace atomic absorption spectrometry for determination of Pt, Pd and Rh after separation and concentration by original in-house developed heterochain polymer S, N-containing sorbent. The methods of sample preparation of spent ceramic-based autocatalysts were considered, two of which were used: autoclave decomposition in mixture of acids HCl:HNO3 (3:1) and high-temperature melting with K2S2O7. Both methods anyway limit the direct determination of analytes by HR CS GFAAS. Using the first method it is an incomplete digestion of spent autocatalysts samples, since the precipitate is Si, and the rhodium metal dissolves with difficulty and partially passes into solution. In contrast to the first method, the second method allow to completely transfer analytes into solution, however, the background signal produced by the chemical composition of the flux, overlaps the analytical zone.It was found, that Pt, Pd and Rh contained in the spent ceramic automotive catalysts could be effectively separated and concentrated by heterochain polymer S, N-containing sorbent, which has high sorption capacity, selectivity and resistant to dilute acids. The chosen HR CS GFAAS analysis conditions enable us to determine Pt, Pd and Rh with good metrological characteristics. The concentrations of Pt, Pd and Rh in two samples of automobile exhaust catalysts were found in range of 0.00015–0.00050; 0.170–0.189; 0.0180–0.0210wt%, respectively. The relative standard deviation obtained by HR CS GFAAS was not more than 5%. Limits of detection by HR CS GFAAS achieved were 6.2·10−6wt% for Pt, 1.8·10−6wt% for Pd, and 3.4·10−6wt% for Rh. Limits of determination achieved by HR CS GFAAS were 1.1·10−5wt% for Pt, 6.9·10−5wt% for Pd, and 8.3·10−5wt% for Rh.To control the accuracy of PGM in sorption concentrates by HR CS GFAAS method, it was appropriate to conduct an inter-method comparative experiment. The researches on the application of atomic-emission spectroscopy method with inductively coupled plasma as a comparative method were conducted. In addition, the trueness control of the obtained results is confirmed by added-found method.

Determination of lead, cadmium and nickel in hennas and other hair dyes sold in Turkey

The concentrations of lead, nickel and cadmium in various hennas and synthetic hair dyes were determined by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS). For this purpose, 1 g of sample was digested using 4 mL of hydrogen peroxide (30%) and 8 mL of nitric acid (65%). The digests were diluted to 15 mL and the analytes were determined by HR-CS GFAAS. All determinations of Pb and Cd were performed using NH4H2PO4 as a modifier. The analytes in hair certified reference materials (CRMs) were found within the uncertainty limits of the certified values. In addition, the analyte concentrations added to hair dye were recovered between 95 and 110%. The limits of detection of the method were 48.90, 3.90 and 12.15 ng g−1 for Pb, Cd and Ni, respectively and the characteristic concentrations were 8.70, 1.42 and 6.30 ng g−1, respectively. Finally, the concentrations of the three analytes in various synthetic hair dyes with different brands, shades and formulae as well as in two henna varieties were determined using aqueous standards for calibration. The concentrations of Pb, Cd and Ni in hair dyes were in the ranges of LOD-0.56 μg g−1, LOD-0.011 ng g−1 and 0.030–0.37 μg g−1, respectively, whereas those in the two hennas were 0.60–0.93 μg g−1, 0.033–0.065 ng g−1 and 0.49–1.06 μg g−1, respectively.

Determination of Pb and Cr in sunscreen samples by high-resolution continuum source graphite furnace atomic absorption spectrometry and direct analysis

A method has been developed for the determination of Cr and Pb in sunscreen samples by high-resolution continuum source graphite furnace atomic absorption spectrometry and direct analysis (HR-CS DS-GF AAS). Eleven commercial samples of different brands and different factors of sun protection sunscreen were analysed. For optimisation of the furnace temperature programme, pyrolysis and atomisation curves with M1 sunscreen sample were performed using a chemical modifier (0.05% Pd+0.03% Mg+0.05% Triton X-100) for Pb and without a modifier for Cr. The figures of merit obtained were: characteristic mass of 10pg and 2.5pg and limit of detection (LOD) of 3.0μgkg−1 and 1.0μgkg−1 for Pb and Cr, respectively, based on a sample mass of 4.5mg. Relative standard deviation (RSD) values were lower than 9%, which are acceptable for direct analysis. For assessment of the accuracy of the method, sunscreen samples were digested. The results obtained with direct determination of Pb and Cr in sunscreen samples and with acid digestion were statistically accordant, using the calibration with aqueous standards, showing that this calibration method is suitable for this application. The method developed for the analysis of sunscreen samples is accurate, simple, fast and suitable for routine application.

Optimization and Application of a Slurry Sampling Method for the Determination of Total Fluorine in Flour Using a High-Resolution Continuum Source Graphite Furnace Molecular Absorption Spectrometer

A slurry sampling method was described for the determination of total fluorine in flour via molecular absorption of calcium monofluoride (CaF) at 660.440 nm using a high-resolution continuum source graphite furnace atomic absorption spectrometer (HR-CS GF AAS). The slurries were prepared in 1 % Triton X-100, kept in an ultrasonic bath for 15 min, mixed in a shaker for 5 min (750 rpm), and then vortexed for 30 s shortly before sampling. The samples were mixed with 40 μg of Ca in the graphite furnace, pyrolyzed at 900 °C, and the absorbances for CaF were measured at 2200 °C. The LOD and characteristic mass of the method were 0.22 and 0.16 ng, respectively. The F concentrations of certified reference bush branches and leaves were determined in the uncertainty limits of the certified values. Finally, the F concentrations of different types of flours were determined applying the optimized conditions.

Cobalt internal standard for Ni to assist the simultaneous determination of Mo and Ni in plant materials by high-resolution continuum source graphite furnace atomic absorption spectrometry employing direct solid sample analysis

A new method is proposed for the simultaneous determination of Mo and Ni in plant materials by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS), employing direct solid sample analysis (DSS) and internal standardization (IS). Cobalt was used as internal standard to minimize matrix effects during Ni determinations, enabling the use of aqueous standards for calibration. Correlation coefficients for the calibration curves were typically better than 0.9937. The performance of the method was checked by analysis of six plant certified reference materials, and the results for Mo and Ni were in agreement with the certified values (95% confidence level, t-test). Analysis was made of different types of plant materials used as renewable sources of energy, including sugarcane leaves, banana tree fiber, soybean straw, coffee pods, orange bagasse, peanut hulls, and sugarcane bagasse. The concentrations found for Mo and Ni ranged from 0.08 to 0.63ngmg−1 and from 0.41 to 6.92ngmg−1, respectively. Precision (RSD) varied from 2.1% to 11% for Mo and from 3.7% to 10% for Ni. Limits of quantification of 0.055 and 0.074ng were obtained for Mo and Ni, respectively.

Determination of Mercury in Istanbul Airborne Particles Using Solid Sampling High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry

ABSTRACTA method for the determination of mercury in airborne particles by solid sampling high-resolution continuum source graphite furnace atomic absorption spectrometry is reported. Fine urban airborne particles were collected every month on quartz filters using a high-volume sampler (500 L/min) in Istanbul, Turkey. The filters loaded with airborne particles were directly introduced into the graphite furnace so that analyte losses during digestion were eliminated. Moreover, to prevent analyte losses in the furnace, no pyrolysis step was taken and silver and gold nanoparticles were used as novel modifiers. The effects of graphite furnace program, pyrolysis and atomization temperature, and mass of sample introduced into the furnace were characterized. The limits of detection in the absence of any modifier, in the presence of silver nanoparticles, and in the presence of gold nanoparticles were 0.52, 0.38, and 0.19 µg/L, respectively. The mercury concentrations in the air particulates were between 0.74 ± 0.10 and 3.65 ± 0.33 µg/L.

Simultaneous determination of cadmium, iron and tin in canned foods using high-resolution continuum source graphite furnace atomic absorption spectrometry

A method was established to simultaneously determine cadmium, iron and tin in canned-food samples using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). The quantification step has been performed using the primary line (228.802nm) for cadmium and the adjacent secondary lines (228.725nm and 228.668nm) for iron and tin, respectively. The selected chemical modifier was an acid solution that contained a mixture of 0.1% (w/v) Pd and 0.05% (w/v) Mg. The absorbance signals were measured based on the peak area using 3 pixels for cadmium and 5 pixels for iron and tin. Under these conditions, cadmium, iron and tin have been determined in canned-food samples using the external calibration technique based on aqueous standards, where the limits of quantification were 2.10ngg−1 for cadmium, 1.95mgkg−1 for iron and 3.00mgkg−1 for tin, and the characteristic masses were 1.0pg for cadmium, 0.9ng for iron and 1.1ng for tin. The precision was evaluated using two solutions of each metal ion, and the results, which were expressed as the relative standard deviation (RSD%), were 3.4–6.8%. The method accuracy for cadmium and iron was confirmed by analyzing a certified reference material of apple leaves (NIST 1515), which was supplied by NIST. However, for tin, the accuracy was confirmed by comparing the results of the proposed method and another analytical technique (inductively coupled plasma optical emission spectrometry). The proposed procedure was applied to determine cadmium, iron and tin in canned samples of peeled tomato and sardine. Eleven samples were analyzed, and the analyte concentrations were 3.57–62.9ngg−1, 2.68–31.48mgkg−1 and 4.06–122.0mgkg−1 for cadmium, iron and tin, respectively. In all analyzed samples, the cadmium and tin contents were lower than the permissible maximum levels for these metals in canned foods in the Brazilian legislation.

High-resolution continuum source graphite furnace atomic absorption spectrometry for the monitoring of Au nanoparticles

This article demonstrates the potential of HR CS GFAAS for establishing the presence of NPs and their average size.

Sequential and simultaneous determination of four elements in soil samples using high-resolution continuum source graphite furnace atomic and molecular absorption spectrometry

An analytical method has been developed for the determination of Cd, Cr, Fe and Al (via the AlH molecule) in soil samples using direct solid sample analysis.

Fast sequential determination of manganese and chromium in vegetable oil and biodiesel samples by high-resolution continuum source graphite furnace atomic absorption spectrometry

HR-CS GF AAS was used for the sequential determination of Mn and Cr in vegetable oil and biodiesel samples.

Determination of Chlorine in Crude Oil by High-Resolution Continuum Source Graphite Furnace Molecular Absorption Spectrometry Using AlCl, InCl, and SrCl Molecules

In this work, high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS) using AlCl, InCl, and SrCl molecules was proposed for direct Cl determination in crude oil. Crude oil analysis was performed by pipetting masses of crude oil directly on the graphite platform. Calibration was performed using aqueous standard solutions containing chlorine. A solution containing Sr2+ ions should be used to increase the sensitivity for AlCl and InCl molecules. For SrCl, only Sr2+ solution was used and the graphite platform should be covered with a Zr permanent modifier. Accuracy was evaluated using certified reference material (NIST 1634c, fuel oil) and also by comparison of results obtained with HR-CS GF MAS to those obtained by microwave-induced combustion (MIC), microwave-assisted extraction (MAE), ASTM D6470-99, and neutron activation analysis (NAA). Significant differences were not observed by comparison of results obtained by HR-CS GF MAS to the certified reference value and...

Solid sampling determination of lithium and sodium additives in microsamples of yttrium oxyorthosilicate by high-resolution continuum source graphite furnace atomic absorption spectrometry

Solid sampling high resolution continuum source graphite furnace atomic absorption spectrometry (SS-HR-CS-GFAAS) methods were developed and studied for the fast and sensitive quantitation of Li and Na additives in microsamples of cerium-doped yttrium oxyorthosilicate (Y2SiO5:Ce) scintillator materials. The methods were optimized for solid samples by studying a set of GFAAS conditions (i.e., the sample mass, sensitivity of the analytical lines, and graphite furnace heating programs). Powdered samples in the mass range of 0.099–0.422mg were dispensed onto graphite sample insertion boats, weighed and analyzed. Pyrolysis and atomization temperatures were optimized by the use of single-element standard solutions of Li and Na (acidified with 0.144mol/L HNO3) at the Li I 610.353nm and Na I 285.3013nm analytical lines. For calibration purposes, the method of standard addition with Li and Na solutions was applied. The correlation coefficients (R values) of the calibration graphs were not worse than 0.9678. The limit of detection for oxyorthosilicate samples was 20μg/g and 80μg/g for Li and Na, respectively. The alkaline content of the solid samples were found to be in the range of 0.89 and 8.4mg/g, respectively. The accuracy of the results was verified by means of analyzing certified reference samples, using methods of standard (solution) addition calibration.

Multiwalled carbon nanotubes as solid sorbent in dispersive micro solid-phase extraction for the sequential determination of cadmium and lead in water samples

The combination of dispersive micro solid-phase extraction (DMSPE) with high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS) was developed for the sequential determination of cadmium and lead in water samples. During the preconcentration step the multiwalled carbon nanotubes (MWCNTs) were used as solid sorbent. MWCNTs were dispersed in water samples containing trace elements to be determined. The samples were mixed for 5min. After the sorption, the aqueous samples were separated by centrifugation. Then, the metal loaded MWCNTs were suspended using a small volume of deionized water and introduced to the atomizer. The experimental parameters including the pH of sample solution, amount of MWCNTs, sample volume and extraction time, as well as main parameters of HR-CS GFAAS were investigated. The concentration limits of detection were 0.001 and 0.03μgL−1 for Cd and Pb, respectively. The preconcentration factors achieved for Cd and Pb were 30 and 15, respectively. The relative standard deviations (RSDs) were 3% and 4% for Cd and Pb, respectively. The accuracy of this method was validated by analyses of NIST SRM 1643e (Trace Elements in Water) and ERM-CA011b (Hard Drinking Water). The measured element contents in these reference materials were in satisfactory agreement with the certified values according to the t-test for a 95% confidence level. The proposed method has been successfully applied for the determination of cadmium and lead in four different water samples (seawater, lake water, mine water and tap water).

Investigation of chemical modifiers for the direct determination of arsenic in fish oil using high-resolution continuum source graphite furnace atomic absorption spectrometry

High-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) has been applied for the development of a method for the determination of total As in fish oil samples using direct analysis. The method does not use any sample pretreatment, besides dilution with 1-propanole, in order to decrease the oil viscosity. The stability and sensitivity of As were evaluated using ruthenium and iridium as permanent chemical modifiers and palladium added in solution over the sample. The best results were obtained with ruthenium as the permanent modifier and palladium in solution added to samples and standard solutions. Under these conditions, aqueous standard solutions could be used for calibration for the fish oil samples diluted with 1-propanole. The pyrolysis and atomization temperatures were 1400°C and 2300°C, respectively, and the limit of detection and characteristic mass were 30pg and 43pg, respectively. Accuracy and precision of the method have been evaluated using microwave-assisted acid digestion of the samples with subsequent determination by HR-CS GF AAS and ICP-MS; the results were in agreement (95% confidence level) with those of the proposed method.

Selenium and its relationship with selenoprotein P and glutathione peroxidase in children and adolescents with Hashimoto’s thyroiditis and hypothyroidism

The essential trace element selenium (Se) is required for thyroid hormone synthesis and metabolism. Selenoproteins contain selenocysteine and are responsible for biological functions of selenium. Glutathione peroxidase (GPx) is one of the major selenoproteins which protects the thyroid cells from oxidative damage. Selenoprotein P (SePP) is considered as the plasma selenium transporter to tissues. The aim of this study was to evaluate serum Se and SePP levels, and GPx activity in erythrocytes of children and adolescents with treated Hashimoto’s thyroiditis, hypothyroidism, and normal subjects.Blood samples were collected from 32 patients with Hashimoto’s thyroiditis, 20 with hypothyroidism, and 25 matched normal subjects. All the patients were under treatment with levothyroxine and at the time of analysis all of the thyroid function tests were normal. GPx enzyme activity was measured by spectrophotometry at 340nm. Serum selenium levels were measured by high-resolution continuum source graphite furnace atomic absorption. SePP, TPOAb (anti-thyroid peroxidase antibody), and TgAb (anti-thyroglobulin antibody) were determined by ELISA kits. T4, T3, T3 uptake and TSH were also measured.Neither GPx activity nor SePP levels were significantly different in patients with Hashimoto’s thyroiditis or hypothyroidism compared to normal subjects. Although GPx and SePP were both lower in patients with hypothyroidism compared to those with Hashimoto’s thyroiditis and normal subjects but the difference was not significant. Serum Se levels also did not differ significantly in patients and normal subjects. We did not find any correlation between GPx or SePP with TPOAb or TgAb but SePP was significantly correlated with Se.Results show that in patients with Hashimoto’s thyroiditis or hypothyroidism who have been under treatment with levothyroxine and have normal thyroid function tests, the GPx, SePP and Se levels are not significantly different.

Determination of silicon in plant materials using direct solid sample analysis with high-resolution continuum source graphite furnace atomic absorption spectrometry

In this work, a method for the determination of silicon in plant material by high-resolution continuum source graphite furnace atomic absorption spectrometry has been developed using direct solid sample analysis. The performance of iridium and rhodium as permanent modifiers alone and combined with the palladium–magnesium modifier in solution was investigated. According to the results, among the investigated modifiers, an improvement in sensitivity and Si signal profile was obtained using 300μg of Rh in combination with 20μg of Pd+12μg of Mg. The optimized pyrolysis and atomization temperatures were 1200 and 2650°C, respectively. Due to the high content of Si in most of the evaluated samples, the analytical line of 221.174nm was chosen. Moreover, an adequate working range (30 to 600ng Si) was achieved after using a minimum gas flow in the atomization stage and the integrated absorbance of the center pixel only. The sample mass varied between 0.03 and 0.50mg, and no spectral interferences were encountered. The limit of detection was 5ngmg−1 and the limit of quantification 17ngmg−1, both were calculated according to the maximum sample mass of 0.50mg. The Si content investigated in ten plant samples varied between 0.5 and 20μgmg−1. The accuracy of the method was evaluated using the certified reference materials NCS ZC73014 (Trace elements in Tea) and NCS ZC73349 (Bush Branches and Leaves) and results presented no significant difference between the certified and found concentrations. Therefore, the obtained results prove that an accurate method has been developed and it could be applied to analyze different plant materials with levels varying in a wide range, with minimum of pretreatment.