Resolution Continuum Source Graphite Furnace Research Articles

A slurry sampling high resolution continuum source graphite furnace atomic absorption spectrometry approach to determine metals in biomass bottom ash

A slurry sampling high resolution continuum source graphite furnace atomic absorption spectrometry approach to determine metals in biomass bottom ash

Use of slow atomization ramp in high resolution continuum source graphite furnace atomic absorption spectrometry for the simultaneous determination of Cd and Ni in slurry powdered chocolate samples

A methodology for simultaneous (not sequential) determination of Cd and Ni in powder chocolate samples by high-resolution continuum source graphite furnace atomic absorption spectroscopy (HR–CS–GF-AAS) and slurry sample analysis was developed. Acid digestion of the samples was not necessary, considering the high total fat content of this type of matrix (above 10 %), and no apparent deterioration of the graphite tubes was even observed once these samples were subjected to analysis. Despite the volatilities of both elements are quite different, simultaneous quantification was achieved using a slow heating ramp atomization, covering a convenient and wide temperature gradient for Cd volatilization at low temperatures and subsequent atomization of Ni at elevated temperatures, using the same heating program without an apparent change in sensitivity. This slow heating ramp was essayed between 200 and 1500 °C·s−1 and optimized at 400 °C·s−1, achieving the simultaneous measuring of Cd in the principal line (228.8018 nm) and using a secondary for Ni (228.9984 nm). No stop events for sequential changes in wavelength or temperature additional steps were involved in the method and molecular spectral interferences overlapping the analyte signals were corrected appropriately by a pragmatic strategy taking advantage of the fine structure signals adjacent to analyte signals within the same spectrum recorded. Palladium matrix modifier and aqueous standards were used for the calibration and determination of both elements in the samples. The method accuracy was successfully confirmed using a reference material (NIST SRM 1573a). An improvement in the sensitivity of Ni was found using a greater number of pixels for signal integration, central and five adjacent pixels (CP ± 5), while a lengthening of the linear range of Cd was obtained by using an attenuated signal (±2) or using only one pixel (CP). The limits of detection were 0.027 μg g−1 and 0.22 μg g−1 for Cd and Ni respectively by this simple methodology using aqueous standards for calibration and the simultaneous determination of both elements in the same measurement. The respective limits of quantification for Cd and Ni were 0.090 and 0.72 μg g−1 and the relative standard deviations in samples (n = 5) were about 4–20% and 0.3–11% for Cd and Ni respectively. The optimized method was used for the determination of both elements in real samples purchased from retail supermarkets finding variable concentrations between 0.5 and 5.7 μg g−1 for Cd and 2.1–10.9 μg g−1 for Ni, comparable to levels reported in the literature referred to elsewhere in the world.

Lead fire assay preconcentration and high resolution continuum source graphite furnace atomic absorption spectrometry for the determination of ultra-trace amounts of Au, Ir, Pd, Pt and Rh in rocks and minerals

In this work, a novel method was reported for the determination of ultra-trace Au, Ir, Pd, Pt and Rh in rocks and minerals. Purified basic lead carbonate instead of commercial lead oxide (PbO) was used as fire assay collector in order to greatly reduce the reagent blank. Au, Ir, Pd, Pt and Rh were enriched in about 5 mg of composite granule of lead fire assay. After the granule was fully dissolved in HNO3, HCl was added to form aqua regia so as to completely digest Au, Ir, Pd, Pt and Rh, then the sample solution were determined by high resolution continuum source graphite furnace atomic absorption spectrometry (HRCS-GFAAS). The decomposition method of chromite was investigated as well as the pyrolysis/atomization temperatures, atomization reading time and effective pixels of CCD detector for the determination of Au, Ir, Pd, Pt and Rh were optimized. Besides, the influence of spectral interference of co-existing elements and the residual amount of lead were discussed. Under the optimal conditions, excellent curve fitting of Au, Ir, Pd, Pt and Rh were obtained between 0.05 and 50 ng mL−1, with the correlation coefficients exceeding 0.9996. The experimental characteristic mass of Au, Ir, Pd, Pt and Rh were 0.0068, 0.052, 0.013, 0.060 and 0.011 ng, respectively. The established method was successfully applied to analyze Au, Ir, Pd, Pt and Rh in Chinese Certified Reference Materials (CRMs), and the determined values were in good agreement with the certified values. The relative standard deviations (RSDs, n = 5) of Au, Ir, Pd, Pt and Rh were between 5.5% and 13% for the determination of GBW07291. The proposed method was sensitive and accurate which could meet the analysis requirement of ultra-trace Au, Ir, Pd, Pt and Rh in rocks and minerals.

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 inorganic contaminants in carbon nanotubes by plasma-based techniques: Overcoming the limitations of sample preparation

In this work, sample preparation of carbon nanotubes (CNTs) for further determination of inorganic contaminants was investigated using a microwave-assisted wet digestion single reaction chamber system (MAWD-SRC). Analytes (Al, As, Ca, Cd, Co, Cr, Fe, La, Mg, Mo, Ni, Pb and Zn) were determined in CNTs by inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS, except for Al, Ca, Fe and Mg). Method parameters were evaluated, as the mass of CNT (25–300 mg), the temperature (220–270 °C) and the time (35-75 min) of irradiation program. The accuracy was evaluated by using a certified reference material (CRM) of CNT and also by comparison of the results with those obtained using neutron activation analysis (NAA) and high resolution continuum source graphite furnace atomic absorption spectrometry with direct solid sampling (DSS-HR-CS-GF AAS). Quantitative recoveries for all elements were obtained using 275 mg of CNTs, 6 mL of 14.4 mol L−1 HNO3 and 0.5 mL of 30% H2O2 with an irradiation program of 65 min (35 min at 270 °C). No statistical difference was observed between the results obtained after the decomposition of CNTs by MAWD-SRC with those obtained by NAA and DSS-HR-CS-GF AAS. No difference was also observed for the results using the proposed method and the values for the CRM of CNT. The use of MAWD-SRC showed good performance for CNTs digestion using relatively high sample mass (up to 275 mg), contributing to low limits of quantification (LOQs) and overcoming the current limitations of sample preparation. To the best knowledge of the authors, this work reports the highest sample mass feasible to be decomposed using wet digestion for CNTs among the methods proposed in literature.

Determination of lead in flour samples directly by solid sampling high resolution continuum source graphite furnace atomic absorption spectrometry

In this study, lead concentrations in various flour samples were determined by high-resolution continuum source graphite furnace atomic absorption spectrometry with solid sampling. Since samples were analyzed directly, the risks and disadvantages of sample digestion were eliminated. Solid flour samples were dried, weighed on the platforms, Pd was added as a modifier and introduced directly into a graphite tube using a manual solid sampler. Platforms and tubes were coated with Zr. The optimized pyrolysis and atomization temperatures were 800°C and 2200°C, respectively. The sensitivities of lead in various flour certified reference materials (CRMs) and aqueous standards were not significantly different. Therefore, aqueous standards were safely used for calibration. The absolute limit of detection and characteristic mass were 7.2pg and 9.0pg of lead, respectively. The lead concentrations in different types of flour samples were found in the range of 25–52μgkg−1. Finally, homogeneity factors representing the heterogeneity of analyte distribution for lead in flour samples were determined.

Simultaneous determination of V, Ni and Fe in fuel fly ash using solid sampling high resolution continuum source graphite furnace atomic absorption spectrometry

A green and simple method has been proposed in this work for the simultaneous determination of V, Ni and Fe in fuel ash samples by solid sampling high resolution continuum source graphite furnace atomic absorption spectrometry (SS HR CS GFAAS). The application of fast programs in combination with direct solid sampling allows eliminating pretreatment steps, involving minimal manipulation of sample. Iridium treated platforms were applied throughout the present study, enabling the use of aqueous standards for calibration. Correlation coefficients for the calibration curves were typically better than 0.9931. The concentrations found in the fuel ash samples analysed ranged from 0.66% to 4.2% for V, 0.23–0.7% for Ni and 0.10–0.60% for Fe. Precision (%RSD) were 5.2%, 10.0% and 9.8% for V, Ni and Fe, respectively, obtained as the average of the %RSD of six replicates of each fuel ash sample.The optimum conditions established were applied to the determination of the target analytes in fuel ash samples. In order to test the accuracy and applicability of the proposed method in the analysis of samples, five ash samples from the combustion of fuel in power stations, were analysed. The method accuracy was evaluated by comparing the results obtained using the proposed method with the results obtained by ICP OES previous acid digestion. The results showed good agreement between them.The goal of this work has been to develop a fast and simple methodology that permits the use of aqueous standards for straightforward calibration and the simultaneous determination of V, Ni and Fe in fuel ash samples by direct SS HR CS GFAAS.

Determination of Cobalt, Iron, and Nickel in High-Purity Silicon by High- Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry Employing Solid Sample Analysis

Analytical Chemistry Department UNESP - Univ. Estadual Paulista, 55 Rua Prof. Francisco Degni

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.

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.

Direct solid sampling determination of lead in cheese varieties by high resolution continuum source graphite furnace atomic absorption spectrometry

Lead concentrations in cheese varieties were determined against aqueous standards using high-resolution continuum source graphite furnace atomic absorption spectrometry with direct solid sampling.

Sequential determination of cadmium and lead in organic pharmaceutical formulations using high-resolution continuum source graphite furnace atomic absorption spectrometry

This paper proposes a method using high resolution continuum source graphite furnace atomic absorption spectrometry (HR CS GFAAS) for the sequential determination of cadmium and lead in organic pharmaceutical formulations. The temperature program for cadmium was established employing the pyrolysis and atomization temperatures of 800°C and 1400°C, respectively, and the atomization temperature of 2000°C for lead, being that the pyrolysis temperature for lead is the same used for the cadmium atomization. The analytical measures were performed using the primary lines for cadmium (228.802nm) and (217.001nm) for lead. The absorbance signals obtained were quantified by peak area using 3 pixels for both analytes, utilizing as chemical modifier an acid mixture palladium-magnesium. Employing the optimized conditions, the method allows the sequential determination of cadmium and lead, with limits of detection and quantification of 4 and 13ngg−1 for cadmium and 49 and 165ngg−1 for lead, respectively. The characteristics masses were also calculated, being 1.6pg for cadmium and 12.4pg for lead. The precision expressed as relative standard deviation (%RSD) were 5.0% for cadmium and 6.2% for lead, determined by ten replicates of a sample solution with cadmium and lead contents of 38 and 303ngg−1, respectively. The method accuracy was evaluated and confirmed by analysis of two certified reference materials of leaves furnished by National Institute of Standards and Technology (NIST). Furthermore, addition/recovery tests were also performed using three different real samples. The recoveries obtained varied from 94 to 114%, it confirming the method accuracy. The method was applied for the determination of cadmium and lead in ten different pharmaceutical formulations and the analyte concentrations found in the samples varied from 16 to 51ngg−1 for cadmium and of 179 to 318ngg−1 for lead, being that for six samples the lead contents were lower than the limit of quantification (165ngg−1) and for three samples the cadmium concentrations were lower than 13ngg−1. All samples were also analyzed employing inductively coupled plasma mass spectrometry (ICP-MS) and the results obtained are agreement with those achieved by HR CS GFAAS.

An improved matrix separation method for characterization of ultrapure germanium (8N)

An improved matrix separation method has been described to characterize ultrapure germanium of 8N (99.999999%) purity. In this method, temperature of the reaction vessel in which in-situ generated chlorine gas reacts with germanium solid material directly is optimized to quantitatively remove Ge matrix from all its impurities. Optimized reaction temperature has been found to be 230±5°C. Recovery studies on more than 60 elements have been carried out at the optimized temperature. Recoveries of all the analytes except As, Se, Sn, Hg, Tl are found to be quantitative. The method has been examined for various amounts of Ge material and found to be suitable even for 10g of Ge sample and provides low parts per billion and trillion levels of process blanks. Determination of concentrations of impurities has been done by inductively coupled plasma quadrupole mass spectrometer (ICP-QMS) and high resolution continuum source graphite furnace atomic absorption spectrometer (HR-CS-GFAAS). In the absence of certified reference materials for ultrapure germanium, accuracy of the proposed method is established by spike recovery tests. Precision of this method is found to vary from 7% to 50% for concentrations between 4 and 0.004ngg−1. Limits of detection (LOD) for the target analytes are found to be between 6 and 0.011ngmL−1 or 1.8–0.003ngg−1 for the proposed procedure. The method has been successfully applied for that characterization of ultrapure germanium material of 8N purity.

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.

Simultaneous determination of Co, Al and Fe by HR CS-GFAAS

In this study, simultaneous determination of Al, Co and Fe by high resolution continuum source graphite furnace atomic absorption spectrometer (HR-CS GFAAS) was performed satisfactorily. For this purpose, the spectral area between 237.148 and 237.403 was monitored and Al, Co and Fe absorbances were detected at absorption lines, 237.312nm, 237.185+237.283+237.386nm and 237.362nm, respectively. The characteristic concentrations and LOD values for the working wavelengths of Co, Al, and Fe were 48.0, 6.00, 54.0µgL−1, and 12.0, 14.0, 16.0µgL−1, respectively. The linear working ranges were spread over 0.01–10, 0.05–2.5 and 0.05–10mgL−1 for Co, Al, and Fe, respectively. In the end, Al, Co and Fe in several certificated reference materials and waste water samples were determined satisfactorily by HR-CS GFAAS. With this proposed method a fast and straightforward simultaneous determination by HR CS AAS shown as possible.

Determination of copper and mercury in phosphate fertilizers employing direct solid sampling analysis and high resolution continuum source graphite furnace atomic absorption spectrometry

The present study proposes the determination of copper and mercury in phosphate fertilizers by direct solid sampling analysis (SS) employing high resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). For Cu determination, two analytical lines were used: 327.3960nm and 249.2146nm. Hg determination was carried out on the line 253.6521nm and 100μg KMnO4 was used as chemical modifier. The optimal pyrolysis temperature for Cu determination was 1300°C. Atomization temperatures for Cu and Hg were 2400 and 1100°C, respectively. External calibration with aqueous standard solutions was adopted for both elements. The limits of quantification (LoQs) and characteristic mass (m0) obtained for Cu determination were 0.4μgg−1 and 1.12ng, respectively, on line 249.2146nm, and 64μgg−1 and 25pg on 327.3960nm. For mercury, LoQ and m0 were 4.8ngg−1 and 39pg, respectively. The accuracy of the proposed methods was confirmed by the analysis of standard reference material (SRM) of Trace Elements in Multi-Nutrient Fertilizer (SRM NIST 695). The precision expressed as relative standard deviation (RSD), was better than 8.2% for Hg and 7.7% for the Cu (n=5), considered satisfactory for microanalysis in solid sample. Four fertilizer samples acquired in commercial establishments in the city of Salvador, Bahia, Brazil, were analyzed. The optimized analytical methods were simple, fast, accurate, precise and free of spectral interferences for the determination of Cu and Hg in phosphate fertilizer samples by SS–HR-CS GF AAS, avoiding the dissolution of the sample, the use of harmful reagents and the generation of residues.

Direct determination of lead in plastic toys by solid sampling high resolution-continuum source graphite furnace atomic absorption spectrometry

Lead concentrations in various plastic toys were determined directly by solid sampling high resolution continuum source graphite furnace atomic absorption spectrometry.

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.

Determination of Manganese in Leisure Foods by Incomplete Digestion-Microemulsion Sampling-High Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry

A fast and effective method was developed for determination of Mn in leisure foods by incomplete digestion-microemulsion sampling-high resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS). Microemulsions were prepared with digestive liquor and n-butyl alcohol as an auxiliary emulsifier after incomplete digestion treatment. The factors influencing determination were investigated by single factor experimental design. The optimal determination conditions were found as follows: the tartaric acid (1 mg/mL) was added as a chemical modifier with the volume of 4 μL; pyrolysis temperature 1100°C; atomization temperature 2000°C. The results showed that the correlation coefficient was better than 0.996, the characteristic concentration was 0.09 μg/L, the precision (RSD) for 6 replicate measurements of Mn was 2.8% and the average of recoveries was 97.3%. F-test and t-test (95% confidence level) in between the proposed method and the microwave digestion-HR-CS GFAAS method had no significant difference. Therefore, the proposed method was accurate and stable with a high practical value. It provided scientific basis for determination of metal elements in food.

Sequence Determination of Cd and Pb in Honey by Incomplete Digestion-High Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry

A fast and effective method was developed for sequence determination of Cd and Pb in honey by incomplete digestion-high resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS). Cd and Pb in some honey samples using incomplete digestion treatment were measured by HR-CS GFAAS. The factors influencing determination were investigated by single factor experimental design. The optimal determination conditions were found as follows: NH4H2PO4(10mg/mL) were added as a chemical modifier with the volume of 5μL; pyrolysis temperature 600°C(Cd) and 800°C(Pb); atomization temperature 1100°C(Cd) and 1400°C(Pb). Detection limits (3σ,n=12) were found to be 0.06 μg/L and 0.78 μg/L for Cd and Pb, respectively. The precisions (RSD) for 6 replicate measurements of Cd and Pb in honeys were 3.8% and 2.6%, respectively. Recoveries of added Cd and Pb were varied from 95% to 103%. Therefore, the proposed method was rapid, accurate and stable with a high practical value. It provided scientific basis for multi-element sequence determination in food.