Continuum Source Electrothermal Atomic Absorption Research Articles

Determination of Cr and Ni in Seawater by High-Resolution Continuum Source Electrothermal Atomic Absorption Spectrometry

Determination of Cr and Ni in Seawater by High-Resolution Continuum Source Electrothermal Atomic Absorption Spectrometry

Fast and simple method for simultaneous determination of palladium and rhodium in spent automotive catalysts by high-resolution continuum source electrothermal atomic absorption spectroscopy

This work established a novel and fast method for the simultaneous determination of palladium and rhodium in spent automotive catalysts by high-resolution continuum source electrothermal atomic absorption spectroscopy (HR-CS ETAAS). For this purpose, a simple approach for the extraction of Pd and Rh from auto catalysts with aqua regia (HCl + HNO3 (3:1)) leaching was developed. The optimum conditions for leaching of both elements in an open system are 4 h, at 108 °C and a solid-to-liquid ratio of 1:40. Palladium and rhodium concentrations in obtained leachate were determined simultaneously in one firing using the less sensitive adjacent secondary lines for Pd at 360.955 nm (7.7% relative sensitivity) and for Rh at 361.251 nm (2.2% relative sensitivity). The pyrolysis and atomization temperatures were 1200 °C and 2600 °C, respectively. Under these conditions, the limits of detection for Pd (0.19 mg kg−1) and Rh (0.48 mg kg−1) were relatively high but the sensitivity of the developed method corresponds to common concentrations of the elements in spent automotive catalysts. The repeatability of the method expressed as a relative standard deviation was typically 10% for Pd and 7% for Rh.The trueness of the method was confirmed by analysis of the certified reference material – spent automobile catalyst (ERM EB 504). The recoveries of Pd and Rh from the spent automobile catalyst were 96.9%, and 87.9%, respectively. The method was successfully applied to the simultaneous determination of Pd and Rh in spent automotive catalysts without preliminary chemical separation.

Determination of Polyorganosiloxanes (by Silicon) in Water by Extraction High-Resolution Continuum Source Electrothermal Atomic Absorption Spectrometry

Determination of Polyorganosiloxanes (by Silicon) in Water by Extraction High-Resolution Continuum Source Electrothermal Atomic Absorption Spectrometry

Determination of Ag in high-purity solutions of copper and nickel by high-resolution continuum-source electrothermal atomic absorption spectrometry (HR-CS-ETAAS)

A need to control the silver content in high-purity copper and nickel samples is attributed to the deterioration of the technical characteristics of materials when the presence of such impurities exceeds the permissible levels. In this study, modes for the determination of Ag in copper and nickel by high-resolution electrothermal atomic absorption spectrometry with a continuum source at a content of 10–6 – 10–5 % have been developed. The optimal temperature regimes of the atomizer program and the amount of chemical modifier introduced were developed proceeding from the results of studying the regularities of atomic absorption measurements of silver in matrix solutions of Cu and Ni (with a concentration of 10 g/liter each). To construct calibration dependences, aqueous standard solutions of the analyte (determination in copper) and aqueous standard solutions of the analyte with the addition of nickel nitrate 10 mg/liter (determination in nickel) were used. The atomization temperature was chosen to be 1600°C. The dosing volume of the solutions in the graphite furnace was always 20 μl. When determining Ag in high-purity copper, different temperatures of the pyrolysis stage were used for measurements with dosing of standard analyte solutions (600°C) and for measurements with dosing of the analyzed copper solution (800°C). In the determination of silver in nickel solutions, the temperature of the pyrolysis stage was 800°C. The developed conditions for the determination of silver were tested in the analysis of high-purity samples of copper and nickel (standard solutions of Inorganic Ventures, USA with a concentration of 10 g/liter) using spiked tests. The maximum value of the relative error of determinations does not exceed 13%. The detection limits for silver were: 1.8 × 10–6 % in copper and 3.2 × 10–6 % in nickel.

Determination of thallium in vegetative plant leaves near industrial areas by high-resolution continuum source electrothermal atomic absorption spectrometry after salt induced cloud point extraction

A rapid analytical procedure is described for the separation and pre-concentration of ultra trace level thallium from the microwave assisted nitric acid digests of plant samples and determination using high resolution continuum source electrothermal atomic absorption spectrometry (HR-CS-ETAAS). The method is based on the extraction of ionic thallium spices formed in-situ in the nitric acid digests of plant leaves with Triton X-100 micelles, in presence of HCl and NaCl. The hydrophobic solubilising sites of Triton X-100 micelles are used for the pre-concentration of hydrophobic species of thallium from bulk aqueous phase into a small surfactant rich phase. The main parameters affecting the extraction process are evaluated and optimized. A rapid temperature program completed within 15 s is used for the determination of thallium using a permanent ZrIr modifier. Under the optimized conditions, the pre-concentration factor and limit of detection are 25 and 0.05 ng mL−1, respectively. A characteristic mass of 12 pg is obtained on measuring the integrated absorbance with central pixel ±1. The recoveries are in the range of 95–99% at 1 ng mL−1 with 2–3% relative standard deviation. The accuracy of the method is verified by analyzing certified reference materials such as BCR 060 aquatic plant and NIST 1572 citrus leaves. The obtained values are in good agreement with the certified values. The procedure is also applied to real samples such as spinach, cabbage, aquatic, and tobacco plant leaves collected near thermal power plants and industrial areas.

Determination of polyorganosiloxanes (by silicon) in water by extraction high-resolution continuum source electrothermal atomic absorption spectrometry

A method for the determination of polyorganosiloxanes (by silicon) in water using high-resolution electrothermal atomic absorption spectrometry with a continuous spectrum source and preliminary extraction of polyorganosiloxanes by benzene from the analyzed sample is proposed. The quantitative determination of polyorganosiloxanes (by silicon) was carried out on a contrAA® 700 atomic absorption spectrometer in a cross-heating furnace. Natural water was used to optimize the parameters of the temperature – time program of the atomizer. To eliminate chemical interference during silicon determination by proposed method, graphite cuvettes were modified with a permanent modifier to form a carbide coating. A solution of sodium tungstate was used as a permanent modifier. Thermal stabilization of silicon in a graphite furnace was achieved in the presence of a mixed palladium-magnesium modifier in the nitrate form. The accuracy of the results was confirmed by spike test. The developed method of analysis was used to determine the content of polyorganosiloxanes (by silicon) in natural water. The metrological characteristics of the method were assessed in the range of determined silicon contents 0.01 – 100 mg/dm3.

Sequential and Simultaneous Determination of Cd, Fe and Ni in Toothpastes Employing Slurry Sampling High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry

Here is reported an analytical method for the multielemental determination of Cd, Fe and Ni in toothpaste employing slurry sampling high-resolution continuum source electrothermal atomic absorption spectrometry (HR-CS ET AAS). Using a single sample aliquot, Cd was determined at 228.802 nm, and, sequentially, Fe (232.036 nm) and Ni (232.003 nm) were simultaneously determined. Pyrolysis and atomization temperatures were 800 and 1500 °C for Cd, respectively. An atomization temperature of 2600 °C was used for Fe and Ni. A Pd and Mg mixture was used as the chemical modifier for standards and samples. The procedure for the slurry preparation was optimized using multivariate methodology with a multiple response function while employing a sample mass of about 250 mg. The optimized conditions were: 0.8 mol L−1 HNO3, 0.5% (m/v) Triton X-100 and a sonication time of 15 min. Using aqueous standards for the calibration, limits of detection and quantification were of 3.2 and 10.8 ng g−1 for Cd, 2.2 and 7.4 µg g−1 for Fe, and 0.044 and 0.148 µg g−1 for Ni. The precision estimated as relative standard deviation (n = 5) was 6.1% for Cd, 3.5% for Fe and 4.4% for Ni. The method accuracy was evaluated by standard addition and recovery tests and the recoveries varied from 93 to 114%. The method was applied for the analysis of five toothpaste samples of different brands. The concentrations ranged from 52.0 to 73.6 µg g−1 for Fe, and < 0.148 to 0.227 µg g−1 for Ni. For Cd, the concentrations were below the limit of detection.

Determination of the dissolved forms of silicon in natural drinking water using high-resolution continuum-source electrothermal atomic absorption spectrometry

A technique for the determination of dissolved forms of silicon in water using high-resolution continuum-source electrothermal atomic absorption spectrometry (HR-CS-ETAAS) is proposed. The quantitative determination of the dissolved forms of silicon was performed using an atomic absorption spectrometer ContrAA 700 with a graphite cross-heating cuvette. Natural water was selected to optimize the temperature-time program of the atomizer. To eliminate chemical interference during the silicon determination by HR-CS-ETAAS, the graphite cuvettes were modified with a permanent modifier to form a carbide coating. A solution of sodium tungstate was used as a permanent modifier. Thermal stabilization of silicon in a graphite furnace was achieved with a mixed palladium-magnesium modifier present in the nitrate form. The developed method was used for determination of the content of the dissolved forms of silicon in water. The developed technique was certified proceeding from the results of the research and the metrological examination by an organization accredited for this type of the activity and registered in Federal information Fund for ensuring the uniformity of measurements (FIF).

Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction Based on Melting of the Donor Phase: a New Approach for the Determination of Trace Elements in Solid Samples

A novel ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) based on melting of the donor phase for the determination of Cd, Cu, and Fe in margarine samples using high-resolution continuum source electrothermal atomic absorption spectrometry (HR-CS ET AAS) is proposed. Considering that margarine is in the solid phase at room temperature, requiring heat for melting, the microextraction process was assisted by an ultrasonic bath to ensure the melting point of the samples and to increase the extraction efficiency of the analytes by UA-DLLME. After the extraction procedure, the aqueous phase was collected and directly introduced into a graphite furnace. The procedure was applied for extraction and multi-element determination, exploring the strategy of simultaneous and sequential determination of analytes by HR-CS ET AAS. A low volume of nitric acid solution in the presence of ethanol and hydrogen peroxide allowed the metals to be separated from the sample in an aqueous phase with subsequent determination by HR-CS ETAAS. In the extraction procedure, 5.0 g of each margarine sample was sonicated under heating in the presence of 100 μL of a solution containing HNO3 0.1 mol L−1, ethanol (95.1%, v v−1), and H2O2 3% (v v−1) in a volume proportion of 2:1:1. The influences of the time of extraction, temperature of extraction, and amplitude of sonication were examined, and the proposed conditions were as follows: extraction time, 10 min; temperature, 60 °C; and amplitude, 100%. Using 5 g of margarine sample, limits of detection of 0.03, 0.52, and 224 ng g−1 were obtained for Cd, Cu, and Fe, respectively. Recovery tests were performed, and the results ranged from 87 to 108% for Cd, 91 to 115% for Cu, and 85 to 112% for Fe. The results obtained by the proposed extraction procedure agreed with those obtained after wet digestion of the sample and determination by inductively coupled plasma optical emission spectrometry (ICP OES).

Direct solid sampling for speciation of Zn2+ and ZnO nanoparticles in cosmetics by graphite furnace atomic absorption spectrometry

The application of nanoparticles (NPs) in science and technology is a fast growing field. Therefore, reliable and straightforward analytical methods are required for their fast determination in different types of samples. This work investigates a method that enables the determination of ZnO NPs, discriminating them from ionic zinc in cosmetic samples. The method is based on direct solid sampling high-resolution continuum source electrothermal atomic absorption spectrometry (SS-HR-CS-GFAAS), and has been applied to determination of ZnO NPs, Zn2+ and total Zn in eye shadow samples. In this work the deconvolution of the atomization peak and the calibration by standard additions have been done in order to discriminate and quantify ionic zinc and ZnO NPs. A Zn wavelength with low sensitivity was selected. The proper optimization of the graphite furnace temperature program, minimizing the mineralization of the sample matrix, enables different atomization profiles between the different chemical species of the analyte. Two multiple response surface designs have been used in order to optimize the adequate furnace program to achieve our aims. All the optimization experiments were performed using a sample of eye shadow. Further, a method for the determination of total Zn by direct solid sampling with calibration by aqueous standards, was also optimized. The optimized method was successfully applied to the determination of ionic Zn and ZnO NPs in different eye shadow samples, and has been validated by recovery assays, obtaining recovery percentages between 80 and 125%. Total Zn concentration in the solid samples was validated by the determination of total Zn by direct solid sampling and by the analysis of the same eye shadow samples digested in microwave oven.

Direct analysis of particulate matter (PM10) for the determination of Be, Cd and Pb using high resolution-continuum source electrothermal atomic absorption spectrometry: Assessment of the potential correlation between analyte content and meteorological parameters

Atmospheric particulate matter (APM) monitoring is a fundamental tool for air pollution management and control. However, the limited amount of an APM sample that is typically available upon collection using specific devices may be a limiting factor to promote reliable chemical analysis. Direct solid analysis is thus a cost-effective alternative to be applied for this purpose, since it simplifies the handling of samples, combining faster analysis to maximum detectability with minimum sample consumption. This study presents the development of methods for the determination of beryllium, cadmium and lead in inhalable particulate matter (PM10) using direct solid analysis and high-resolution continuum source electrothermal atomic absorption spectrometry. The temperature program and the use of chemical modifiers were optimized for each individual analyte. Zirconium was used as a permanent modifier for the determination of Be, whereas Pd and Mg were co-injected as chemical modifiers for the determination of Cd and Pb. The potential interferences and calibration strategies were also evaluated. Under optimized conditions, calibration against aqueous standards was proven feasible and detection limits of 0.001, 0.001 and 0.004 ng m−3 for Be, Cd and Pb, respectively, were achieved. The methods were applied to the determination of the referred analytes in 28 samples of PM10 collected at an urban site in the city of Florianópolis, in the State of Santa Catarina, Brazil. Chemometric treatment of data considering analyte content in addition to meteorological parameters (accumulated rainfall, sunlight incidence and wind speed) showed a detectable correlation between these parameters. Samples could be statistically differentiated based on separate loadings for Cd and Pb, which was opposite to Be, for instance. Hence, there is the possibility to correlate these parameters in order to establish a relationship between the origin of the elements in the PM10 samples and the impact of meteorological conditions on their distribution in solid atmospheric particles.

In situ synthesis and preconcentration of cetylpyridinium complexed hexaiodo platinum nanoparticles from spent automobile catalytic converter leachate using cloud point extraction

In the present study, a green chemistry based cloud point extraction (CPE) method has been developed for the in situ synthesis and preconcentration of cetylpyridinium complexed hexaiodo platinum nanoparticles (Pt-I NP) from the leachate of spent automobile catalytic converter using potassium iodide (KI) and assisted by a combination of cationic and non-ionic surfactants; cetylpyridinium bromide (CPB) and Triton X-114, respectively. The process parameters such as concentrations of hydrochloric acid, platinum, KI, sodium chloride, CPB, Triton X-114; incubation temperature and complexation time on CPE were optimized. The synthesized nanoparticles were characterized by UV–visible spectroscopy (UV–vis), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and zeta potential techniques. The formation of Pt-I NP was followed with UV–vis. The XRD pattern established the tetragonal crystal structure of the produced nanoparticles. The nanoparticles were spherical in shape and the particle size obtained with TEM was about 5.6 nm. Further, the preconcentrated nanoparticles were quantified by continuum source electro-thermal atomic absorption spectrometry (ET-AAS) and a preconcentration factor of 25 was obtained for a reaction volume of 25 mL. The accuracy of the developed method was confirmed by analyzing the certified reference materials such as CCRMP PTM-1a (copper-nickel sulphide matte) and CCRMP PTC-1a (copper-nickel sulphide concentrate). The current CPE protocol demonstrates advantages such as simultaneous synthesis and preconcentration; synthesis at micromolar concentration from metal scrap, higher nanoparticle recovery; biodegradability and biocompatibility of the employed surfactants and dual solubility of the synthesized Pt-I NP. Thus, the developed method can be applied for the separation, large scale synthesis and preconcentration of Pt-I NP from various environmental and industrial wastes, in a single pot.

«Atom» software for atomic spectral analysis

«Atom» software is used in integrated spectral devices for atomic emission and atomic absorption analysis produced by «VMK-Optoélektronika». Development of the new spectral instruments and upgrading of existing devices, birth of new mathematical methods and algorithms for processing spectral information, as well as user stories motivate and promote improvement of the software. This paper presents the main developments and most noticeable changes in «Atom «software for the period 2017 – 2018. The developed 64-bit version of «Atom» software removed the limitation on the amount of recorded sequences of spectra and significantly speeded up their processing by parallelizing the calculations on the processor cores (rather important step, for example, in scintillation atomic emission spectrometry). To implement continuum source electrothermal atomic absorption spectrometry for simultaneous multi-element analysis, we have developed the «Automatic Dispenser» and «Absorption Spectrometer» tools and have implemented the method proposed by D.A. Katskov to linearize calibration dependences in a wide range of concentrations. The possibility of spectrophotometric determination of substances in the solutions of their mixtures has been also implemented. The «Barcode Scanner» and the «Automatic Start of Measurement» tools have been developed to speed up and automate the analysis procedure. The software is supplemented with a set of useful functions designed for further development of analytical methods and programs of analysis.

Method development for the determination of bromine via molecular absorption of barium monobromide by high-resolution continuum source molecular absorption spectrometry

A challenging novel method was developed for the determination of bromine via molecular absorption of barium monobromide (BaBr) using a high-resolution continuum source electrothermal atomic absorption spectrometer (HR-CS ETAAS).

Direct determination of lead in bones using slurry sampling and high-resolution continuum source electrothermal atomic absorption spectrometry

Development of a robust, sensitive, fast, accurate and environmentally friendly method enabling for the first time routine direct determination of Pb in bone samples by HR-CS-ETAAS.

High-resolution continuum-source electrothermal atomic absorption spectrometer for simultaneous multi-element determination in the spectral range of 190–780 nm

We have built a prototype atomic absorption spectrometer with an electrothermal atomizer and continuum light source for simultaneous multi-element determination.

Determination of As, Sb and Hg in water samples by flow injection coupled HR CS ETAAS with an in situ hydride generator

A chelating sorbent which employs magnetic nanoparticles (MNPs) functionalized with 1,5-bis(di-2-pyridil)methylene thiocarbohydrazide (DPTH-MNPs) was used to develop a simple method for the analysis of trace amounts of metal ions (As, Sb and Hg) present in environmental samples combining on-line magnetic solid phase extraction (MSPE) with atomic spectrometry. The application of hydride generation with high resolution continuum source electrothermal atomic absorption spectrometry (HR CS ETAAS) improves the sensitivity of As, Sb and Hg determination.This method has proven to have a high sensitivity with detection limits of 0.25 μg L−1, 0.003 μg L−1 and 0.22 μg L−1 for As, Sb and Hg, respectively. Besides, the proposed method was applied in the sequential determination of the 3 elements mentioned above with a sample throughput of about 16.7 h−1, thereby, reducing the time of analysis and the volume of reagents and sample required. This method was applied to determine the target elements in a TMDA 54.5 and TM 24.3 certified reference materials, and seawater collected from Malaga Bay. The results showed good agreement with the certified values.

Graphene oxide based dispersive micro solid phase extraction for selective preconcentration of erbium from water samples and its determination by high-resolution continuum source electrothermal atomic absorption spectrometry

Graphene oxide based dispersive micro solid phase extraction for selective preconcentration of erbium from water samples and its determination by high-resolution continuum source electrothermal atomic absorption spectrometry

Determination of Pb, Cu and Fe in ethanol fuel samples by high-resolution continuum source electrothermal atomic absorption spectrometry by exploring a combination of sequential and simultaneous strategies

An analytical method was developed for the sequential and simultaneous determination of Pb, Cu and Fe in ethanol fuel samples using high-resolution continuum source electrothermal atomic absorption spectrometry (HR-CS ET AAS). The sample preparation consisted in a simple dilution of the ethanol fuel with 0.1molL−1 HNO3. First, Pb was determined at 217.0005nm, using pyrolysis and atomization temperatures of 850°C and 1400°C, respectively. Sequentially, after changing the wavelength, Cu (216.5090nm) and Fe (216.4550nm) were determined simultaneously from a single sample aliquot, using an atomization temperature of 2400°C (Cu and Fe). These instrumental determination steps were performed in approximately 3min. Pd/Mg and NH4H2PO4 solutions were examined as chemical modifiers; however, the best signals were obtained without the use of modifiers. Under the optimized conditions of pyrolysis and atomization temperature, acidity and sample volume, the method allowed the sequential and simultaneous determination of Pb, Cu and Fe in ethanol fuel, and the limits of detection and quantification were 0.94 and 2.84μgkg−1 for Pb, 3.06 and 9.35μgkg−1 for Cu and 136.0 and 408.0μgkg−1 for Fe, respectively. The measurement precisions, expressed as the relative standard deviation (n=10; 12.8μgkg−1 for Pb, 63.8μgkg−1 for Cu and 3400μgkg−1 for Fe) were 7, 3 and 4% for Pb, Cu and Fe, respectively. The maximum ethanol content and acidity of the solution were investigated, and an ethanol concentration of 80% (v v−1) with samples diluted with 0.1molL−1 HNO3 was selected prior to determination by HR-CS ET AAS. Addition and recovery tests were performed, and the results ranged from 82 to 111% for Pb, 84 to 109% for Fe and 96 a 113% for Cu. The matrix effect was evaluated by comparing the calibration curves prepared in alcohol and aqueous media, and the results indicated that external calibration was possible. The proposed method was applied for the determination of Pb, Fe and Cu in ethanol fuel samples, and the maximum concentrations were found to be 2.04μgkg−1 for Pb, 24.3μgkg−1 for Cu and 2.465μgkg−1 for Fe.

Slurry sampling high-resolution continuum source electrothermal atomic absorption spectrometry for direct beryllium determination in soil and sediment samples after elimination of SiO interference by least-squares background correction

In this work a simple, efficient, and environmentally-friendly method is proposed for determination of Be in soil and sediment samples employing slurry sampling and high-resolution continuum source electrothermal atomic absorption spectrometry (HR-CS-ETAAS). The spectral effects originating from SiO species were identified and successfully corrected by means of a mathematical correction algorithm. Fractional factorial design has been employed to assess the parameters affecting the analytical results and especially to help in the development of the slurry preparation and optimization of measuring conditions. The effects of seven analytical variables including particle size, concentration of glycerol and HNO3 for stabilization and analyte extraction, respectively, the effect of ultrasonic agitation for slurry homogenization, concentration of chemical modifier, pyrolysis and atomization temperature were investigated by a 27−3 replicate (n = 3) design. Using the optimized experimental conditions, the proposed method allowed the determination of Be with a detection limit being 0.016mgkg−1 and characteristic mass 1.3pg. Optimum results were obtained after preparing the slurries by weighing 100mg of a sample with particle size < 54µm and adding 25mL of 20% w/w glycerol. The use of 1μg Rh and 50μg citric acid was found satisfactory for the analyte stabilization. Accurate data were obtained with the use of matrix-free calibration. The accuracy of the method was confirmed by analysis of two certified reference materials (NIST SRM 2702 Inorganics in Marine Sediment and IGI BIL-1 Baikal Bottom Silt) and by comparison of the results obtained for ten real samples by slurry sampling with those determined after microwave-assisted extraction by inductively coupled plasma time of flight mass spectrometry (TOF-ICP-MS). The reported method has a precision better than 7%.