Electrothermal Atomization Atomic Absorption Spectrometry Research Articles

Determination of As, Bi, Pb, Sb, Sn in copper, nickel and alloys on their base by electrothermal atomization atomic absorption spectrometry (ETAAS)

Copper and nickel-based alloys are widely used in various industrial settings. Their properties directly depend on the impurities and alloying additives present. Therefore, monitoring of their content in the composition of alloys is still an urgent task. Analytical characteristics of the methods used for determination As, Bi, Pb, Sb, and Sn in copper, nickel, and alloys on their base are studied using electrothermal atomic absorption spectrometry (ETAAS) with selective radiation sources, deuterium background correction, longitudinally heated graphite tube, and high-resolution ETAAS with a continuous source and a transversely heated atomizer. The parameters of the temperature program of the atomizer were optimized for both version of the atomic absorption spectrometry. The revealed interfering effect of the matrix (Cu and Ni) of the studied samples significantly distorts the analytical signals of the analytes and results in significant non-selective absorption. It is shown that when constructing calibration dependencies using ETAAS with selective radiation sources, it is necessary to add a matrix component to the calibration solutions, whereas for high-resolution ETAAS it is possible to avoid introduction of the matrix component without increasing the error of analysis. The developed procedures were tested in analysis of the high-purity copper and nickel samples and standard samples of the composition of the alloys based on copper VSM14-5 (rough copper), VSM14-6 (bronze), and nickel VSN2-2. The achieved detection limits for high-resolution ETAAS with a continuous source leveled at n × 10 –5 %, whereas for low-resolution ETAAS with selective radiation sources the detection limits were higher by an order of magnitude. To determine lower concentrations of the elements in such materials, separation of the sample matrix should be used.

Determination of Pb (II), Cu (II), Co (II), Mn (II), and Fe (III) by electrothermal atomization atomic absorption spectrometry after preconcentration with nanofibers

The results of sorption preconcentration of some heavy metal (HM) ions with their subsequent determination in natural and drinking water by electrothermal atomization atomic absorption spectrometry (ETAAS) are presented. The sorption and desorption (0.01 – 1 M HNO3) of lead, copper, iron, cobalt and manganese ions from aqueous media on nanofiber samples obtained from polyacrylonitrile (PAN) with subsequent directed modification by 1.25 M NaOH solution upon heating (70°C) (PAN*) are studied and optimized. Nanofibers were obtained by capillary-free electroforming from solutions of PAN in dimethylformamide. This method is advantageous for the simplicity of equipment, high energy efficiency of nanofiber production, versatility and flexibility in controlling process parameters and allows production of nanomaterials with desired properties. The values of the extraction degree (95.8 – 99.5%) and selectivity coefficients for competing pairs of metal ions are calculated: вPb/Cu = 1.2; вPb/Co = 2.8; вPb/Mn = 3.2;вCu/Co = 1.7; вCu/Mn = 3.7; вCo/Mn = 2.5. A comparative analysis of the sorption activity of the obtained nanofibers revealed that the character of lead, copper, cobalt and manganese ion sorption by nanofibers is non-selective at pH 6 – 8 and selective for iron (III) ions at pH  3. A technique of sorption-atomic absorption determination of the aforementioned metal ions in real objects with preliminary nanofiber concentration at the level of tenths and hundredths of MPC is proposed. Non-woven materials based on modified PAN are used as effective extractants of nanogram quantities of HM ions. The detection limits for heavy metal ions are 40 – 80 ng/dm3.

Preconcentration of Pb with Aminosilanized Fe3O4 Nanopowders in Environmental Water Followed by Electrothermal Atomic Absorption Spectrometric Determination

A new preconcentration method to determine lead in environmental waters using the aminosilanized magnetite Fe3O4 powder sorbent has been developed. The preconcentration method was combined with electrothermal atomization atomic absorption spectrometry (ETAAS) and a graphite atomizer. Trace amount of sorbent (3 mg) could be applied into the preconcentration of Pb. According the preconcentration, the detection limits were 14 and 19 pg·mL−1 with bare and aminosilanized Fe3O4, respectively. The effect of interferent elements such as Al, Ca, Co, Fe, K, Mg, Na, Ni, and Zn (1000 ng·mL−1 versus Pb 1 ng·mL−1) on the preconcentration of Pb using bare magnetite was evaluated, and some elements (Al, Ni, and Zn) were found to interfere with the Pb preconcentration. The aminosilanized Fe3O4 sorbent was found to be effective in eliminating the severe interferences. The enrichment factors were 34 for the preconcentration with aminosilanized Fe3O4. The recovery of spiked Pb in the case of the sorbent with aminosilanized Fe3O4 was in the range of 75 to 110%. From the analytical data, the preconcentration technique was found to be useful for the determination of trace lead in environmental waters.

A green on-line digestion system using 70% hydrogen peroxide and UV radiation for the determination of chromium in beer employing ETAAS

This work proposes an on-line digestion system employing 70% (w/w) hydrogen peroxide and UV radiation for producing hydroxyl radicals for the determination of chromium in beer samples by electrothermal atomization atomic absorption spectrometry (ETAAS). The digester system consists of a closed wooden box, which is painted black internally, containing a PTFE tube wrapped around a 15 W UV lamp. During the mineralization step, a peristaltic pump is employed to propel the sample solution over the UV lamp. The experimental factors UV irradiation time and hydrogen peroxide volume were optimized using a two-level full factorial design. Degradation curves at different pH conditions demonstrated that the digestion of beer is faster at alkaline pH. The results demonstrated that, in the presence of 70% H2O2 and 15 W UV radiation, 75% of the chromophore species is degraded with an irradiation time of 25 min. The degradation kinetic curves of beer samples under different conditions were also evaluated. The apparent kinetic constant (kapp) found for the process assisted by 70% H2O2 and 15 W UV light was 0.0668 min−1 (R2 = 0.9936). The on-line digestion procedure with a sample flow rate of 2 mL min−1 for 45 min allowed the determination of chromium in beer samples by ETAAS, utilizing the external calibration technique, with the analytical line 357.9 nm, in the presence of magnesium as chemical modifier with limits of detection and quantification of 0.86 and 2.90 μg L−1, respectively. The method accuracy was confirmed by the analysis of the certified reference material of ERM-CA713 wastewater provided by the European Reference Materials. Six beer samples were digested and the chromium was determined. The contents found varied from 4.26 to 33.28 μg L−1. Addition/recoveries tests were also performed to evaluate the accuracy method. The recoveries obtained varied from 93.2 to 96.4%.

A closed inline system for sample digestion using 70% hydrogen peroxide and UV radiation. Determination of lead in wine employing ETAAS

This paper proposes a closed inline system for decomposition of wine, aiming at the determination of lead using electrothermal atomization atomic absorption spectrometry (ETAAS). The system is built using a 0.8 mm diameter PTFE tube, which is wrapped around an 8 W UV lamp. The sample in the presence of 70% hydrogen peroxide is circulated on an 8 W UV lamp at the flow rate of 1 mL min−1 for 45 min. Under these conditions, the carbon content varied from 10% to 2% for a red wine sample before and after digestion, respectively. The system has allowed the determination of lead in wine samples using the analytical line 283.306 nm in the presence of aluminum as the chemical modifier and pyrolysis and atomization temperatures of 800 and 1800 °C, respectively. Then, lead can be quantified employing the external calibration technique with limits of detection 0.27 and quantification 0.89 µg L−1, and characteristics mass of 18 pg. The precision expressed by relative standard deviation (RSD%) was 2.13%, calculated using six replicates of a digested solution of a wine sample with the lead content of 16.35 µg L−1. For evaluation of the accuracy method, two wine samples were analyzed simultaneously by the method proposed and also by inductively coupled plasma mass spectrometry (ICP-MS). A statistical test demonstrated no significant difference between the means obtained by these two techniques. Also, experiments involving addition/recovery tests confirmed the method's accuracy. The system was employed for digestion and determination of lead in four Brazilian wine samples. The lead content varied from 2.19 to 43.48 µg L−1.

Content and Bioaccessibility of Aluminium in Duplicate Diets from Southern Spain

Aluminium is found naturally in foods and beverages, but levels increase notably during processing, packaging, storage, and cooking, as a consequence of its presence in food additives and the wide use of aluminium utensils and vessels. Dietary intake of Al was estimated in 2 population groups in southern Spain (families and university students) in a duplicate diet sampling study. Diets were sampled for 7 consecutive days, and Al was determined in acid-mineralized samples with electrothermal atomization-atomic absorption spectrometry (ETA-AAS). Mean values for Al intake were 2.93 and 1.01 mg/d in families and students, respectively, ranging from 0.12 to 10.00 mg/d. Assuming an average adult weight of 60 kg, the mean dietary exposures to aluminium were 0.34 and 0.12 mg/kg body weight/week in these groups, which amounted to 17% and 6% of the 2 mg/kg body weight estimated as the tolerable weekly intake by the Joint FAO/WHO Expert Committee on Food Additives. Bioaccessibility of dietary Al tested with in vitro studies ranged from 0.30 to 17.26% (absorbable fraction). The highest aluminium intakes were observed in subjects consuming diets with a low adherence to the Mediterranean diet, which were associated to high consumption of processed and canned food. On the contrary, subjects consuming diets with a high adherence to the Mediterranean diet patterns showed the lowest Al intakes. The present findings are useful for giving both a reliable estimate of total aluminium dietary intake and tolerable intake levels according to usual dietary habits.

On-line solid phase extraction of Cd from protein fractions of serum using oxidized carbon nanotubes coupled to electrothermal atomization atomic absorption spectrometry

This work presents a sensitive and accurate method for Cd determination in serum protein fractions separated by cellulose acetate electrophoresis (CAE). The determinations were carried out by on-line solid phase extraction using oxidized carbon nanotubes coupled to electrothermal atomization atomic absorption spectrometry (ETAAS). The detection and quantification limits were 10ngL−1 and 35ngL−1 respectively with a precision of 4.0% as relative standard deviation. This procedure joined the simplicity of protein separation by CAE, the preconcentration properties of solid phase extraction using ox-CNT and the excellent sensitivity attainable by ETAAS. The method was applied to samples with biological relevance (humans and experimental rats). Our work demonstrated that Cd could be determined in serum protein fractions separated by electrophoresis with good accuracy using the proposed method.

Preconcentration of trace elements by adsorption onto a niobium wire for electrothermal atomization atomic absorption spectrometry with a tungsten tube atomizer

In the present work, a new preconcentration method of trace elements by adsorption onto a niobium wire has been developed for electrothermal atomization atomic absorption spectrometry (ETAAS) with a tungsten tube atomizer. Detection limits (pg·mL−1) by this method combined with ETAAS were 45 for bismuth, 7.0 for cadmium, 20 for copper, 1.3 for gold, 36 for lead, 65 for manganese, 9.5 for rhodium and 19 for silver.

A new flow injection preconcentration method based on multiwalled carbon nanotubes for the ETA-AAS determination of Cd in urine

A new flow injection (FIA) procedure for the preconcentration of cadmium in urine using multiwalled carbon nanotubes (MWCNT) as sorbent and posterior electrothermal atomization atomic absorption spectrometry (ETA-AAS) Cd determination has been developed. Cadmium was retained in a column filled with previously oxidized MWCNTs and it was quantitatively eluted with a nitric acid solution. The parameters influencing the adsorption–elution process such as pH of the sample solution, amount of sorbent and flow rates of sample as well as eluent solutions have been studied. Cd concentration in the eluent was measured by ETA-AAS under the optimized conditions obtained. The results indicated the elimination of urine matrix effect as a consequence of the preconcentration process performed. Total recovery of cadmium from urine at pH 7.2 using a column with 45mg of MWCNTs as sorbent and employing a HNO3 0.5molL−1 solution for elution was attained. The detection limit obtained was 0.010μgL−1 and the preconcentration factor achieved was 3.4. The method showed adequate precision (RSD: 3.4–9.8%) and accuracy (mean recovery: 97.4–100%). The developed method was applied for the determination of cadmium in real urine samples from healthy people (in the range of 0.14–2.94μgL−1) with satisfactory results.

Comparison of four analytical techniques based on atomic spectrometry for the determination of total tin in canned foodstuffs

Different techniques for the determination of total tin in beverages and canned foods by atomic spectrometry were compared. The performance characteristics of inductively coupled plasma-mass spectrometry (ICP-MS), hydride generation-inductively coupled plasma-atomic emission spectrometry (HG-ICP-AES), electrothermal atomisation-atomic absorption spectrometry (ETA-AAS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES) were determined in terms of linearity, precision, recovery, limit of detection, decision limit (CCα) and detection capability (CCβ) (Decision 2002/657/EC). Calibration ranges were covered from ng l−1 to mg l−1 level. Limits of detection that ranged from 0.01, 0.05, 2.0 to 200 µg l−1 were reached for ICP-MS; HG-ICP-AES; ETA-AAS and ICP-AES, respectively. Precision, calculated according to ISO 5725-2 for repeatability and within-laboratory reproducibility and expressed as relative standard deviation (RSD), ranged from 1.6% to 4.9%; and recovery, based on Decision 2002/657/EC, was found to be between 95% and 110%. Procedures for the mineralisation or extraction of total tin were compared. Wet digestion, sequentially, with nitric acid and hydrogen peroxide provided the best results. The influence of possible interferences present in canned food and beverage was studied, but no interference in the determination of tin was observed. Since maximum levels for tin established by European Union legislation vary from 50 mg kg−1 in canned baby foods and infant foods up to 200 mg kg−1 in canned food, ICP-AES was chosen as the preferred technique for routine analysis thanks to its good precision, reliability and ease of use. The accuracy of this routine method was confirmed by participation in six proficiency test schemes with z-scores ranging from −1.9 to 0.6. Several canned foodstuffs and beverage samples from a local market were analysed with this technique.

Determination of iron in seawater by electrothermal atomic absorption spectrometry and atomic fluorescence spectrometry: A comparative study

Two methods available for direct determination of total Fe in seawater at low concentration level have been examined: electrothermal atomization atomic absorption spectrometry (ETAAS) and electrothermal atomization laser excited atomic fluorescence spectrometry (ETA-LEAFS). In a first part, we have optimized experimental conditions of ETAAS (electrothermal program, matrix chemical modification) for the determination of Fe in seawater by minimizing the chemical interference effects and the magnitude of the simultaneous background absorption signal. By using the best experimental conditions, a detection limit of 80 ng L −1 (20 μL, 3 σ) for total Fe concentration was obtained by ETAAS. Using similar experimental conditions (electrothermal program, chemical modification), we have optimized experimental conditions for the determination of Fe by LEAFS. The selected experimental conditions for ETA-LEAFS: excitation wavelength (296.69 nm), noise attenuation and adequate background correction led to a detection limit (3 σ) of 3 ng L −1 (i.e. 54 pM) for total Fe concentration with the use a 20 μL seawater sample. For the two methods, concentration values obtained for the analysis of Fe in a NASS-5 (0.2 μg L −1) seawater sample were in good agreement with the certified values.

Validation of a method to quantify chromium, cadmium, manganese, nickel and lead in human whole blood, urine, saliva and hair samples by electrothermal atomic absorption spectrometry

For biological monitoring of heavy metal exposure in occupational toxicology, usually whole blood and urine samples are the most widely used and accepted matrix to assess internal xenobiotic exposure. Hair samples and saliva are also of interest in occupational and environmental health surveys but procedures for the determination of metals in saliva and hair are very scarce and to our knowledge there is no validation of a method to quantify Cr, Cd, Mn, Ni and Pb in four different human biological materials (whole blood, urine, saliva and axilary hair) by electrothermal atomization atomic absorption spectrometry (ETAAS). In the present study, quantification methods for the determination of Cr, Cd, Mn, Ni and Pb in whole blood, urine, saliva and axilary hair were validated according to the EU common standards. Pyrolisis and atomization temperatures have been determined. The main parameters evaluated were: detection and quantification limits, linearity range, repeatability, reproducibility, recovery and uncertainty. Accuracy of the methods was tested with the whole blood, urine and hair certified reference materials and recoveries of the spiked samples were acceptable ranged from 96.3 to 107.8%.

Speciation analysis of thallium using electrothermal AAS following on-line pre-concentration in a microcolumn filled with multiwalled carbon nanotubes

The enrichment ability of carbon nanotubes (CNTs) was investigated and a new method established for the determination of trace thallium species in environmental samples using electrothermal atomization-atomic absorption spectrometry (ETAAS). The CNTs were employed as sorbent substrate in a continuous flow system coupled to ETAAS. Parameters influencing the recoveries of thallium were optimized. Under optimal conditions, the detection limit and precision of the method were 0.009 µg L−1 and 3.9%, respectively. The method was applied to the determination of thallium in real environmental samples and the recoveries were in the range from 96 to 100%. This system was able to separate thallium (I) from the matrix, which allowed its selective determination. The total thallium content was then determined by reducing Tl(III) with hydroxylamine. All these experimental results indicated that this new procedure can be applied to the determination of trace thallium in drinking water samples.

Assessing state-of-the-quality of Jaffe creatinine assay results using proficiency testing data

Results of an interlaboratory study are reported for the determination of lead in urine. Two levels of a lyophilized material containing biologically-bound lead were prepared using pooled urine obtained from lead-poisoned children undergoing the CaNa2EDTA mobilization test. The materials were circulated to a group of reference laboratories that participate in the `New York State Proficiency Testing Program for Blood Lead'. Results of the initial round-robin gave all-method consensus target values of 145±22 μg/l (S.D.) for lot 17 and 449±43 μg/l (S.D.) for lot 20. The interlaboratory exercise was repeated some 5 years later and consensus target values were re-calculated using the grand mean (excluding outliers) of results reported by laboratories using electrothermal atomization atomic absorption spectrometry (ETAAS). The re-calculated target values were 139±10 μg/l (S.D.) and 433±12 μg/l (S.D.). The urine reference materials were also analyzed for lead by several laboratories using other instrumental techniques including isotope dilution (ID), inductively coupled plasma (ICP) mass spectrometry (MS), flame atomic absorption with extraction, ICP-atomic emission spectrometry, ID-gas chromatography MS and flow injection-hydride generation AAS, thus providing a rich source of analytical data with which to characterize them. The materials were also used in a long-term validation study of an ETAAS method developed originally for blood lead determinations that has since been used unmodified for the determination of lead in urine also. Recently, urine lead method performance has been tracked in a proficiency testing program specifically for this analysis. In addition, a number of commercial control materials have been analyzed and evaluated.

Traffic‐Related Elements in Airborne Particulate Matter

This review covers the investigations done over the last few years to quantify key traffic‐related elements, namely, Pb, Pd, Pt, Rh, and Sb in atmospheric aerosols. From this standpoint, the role played by analytical techniques as diverse as electrothermal atomization atomic absorption spectrometry (ET‐AAS), total reflection X‐ray fluorescence (TXRF) spectrometry, and inductively coupled plasma‐mass spectrometry (ICP‐MS) is also surveyed as a substantial amount of research is presently being performed to further improve the instrumental approach. In their turn, neutron activation analysis (NAA) and particle‐induced X-ray emission (PIXE) are nuclear techniques that were and are employed in this context. The application of ICP‐MS for fractionation studies based on the separation of particles according to their aerodynamic diameter and the use of chemical extraction for metal partitioning in airborne particulate matter and their speciation analysis are also discussed. This survey contains 91 references and covers primarily the literature published over the last decade.

Evaluation of a second‐generation portable blood lead analyzer in an occupational setting

A new blood lead testing instrument has qualities that make the instrument attractive for on-site testing of occupational lead exposures. This study evaluated the accuracy of the instrument when used in a manufacturing setting, and examined the impact of blood storage and shipment on results. Venous blood specimens (n=121) were obtained and immediately analyzed on-site using the new instrument. They were then shipped to a reference laboratory and analyzed using electro-thermal atomization atomic absorption spectrometry (ETAAS), and retested using the new instrument. The cohort blood lead concentration averaged 40.1 microg/dl. Results obtained on the new analyzer with freshly collected blood averaged 38.7 microg/dl. The mean difference of 1.2 microg/dl on paired samples was not statistically significant. Following blood shipment and storage, results on the analyzer increased to an average of 42.4 microg/dl. The mean increase of 3.0 microg/dl on stored blood samples also failed to reach statistical significance. Under OSHA proficiency test acceptability requirements, 94% of the results had satisfactory agreement. The new analyzer might be a useful tool for on-site monitoring of occupational lead exposures. The manufacturer's instructions should be adhered to with respect to specimen age and storage requirements.

Mechanism of sensitivity difference between trivalent inorganic As species [As(III)] and pentavalent species [As(V)] with inductively coupled plasma spectrometry

The pentavalent inorganic arsenic (As) species [As(V)] is found to be 4% more sensitive than the trivalent species [As(III)] with inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES). Although there was no sensitivity difference between As(III) and As(V) with atomic absorption spectrometry (AAS), electrothermal atomization atomic absorption spectrometry (ETAAS), X-ray fluorescence (XRF), and neutron activation analysis (NAA). The calibration solutions of As(III) and As(V) were gravimetrically prepared from the unique mother standard solution of JCSS As standard solution which is certified by Japan Calibration Service System (JCSS). Since it is essential to use the calibration solutions with exactly the same concentration of As in order to accurately compare the sensitivities between As(III) and As(V). The mechanisms of this sensitivity difference between them were investigated by ICP-MS and ICP-OES, and it elucidated that the formation rates of hydride polyatomic species of As were definitively different between As(III) and As(V) species in the plasma. This phenomenon directly affected their sensitivities with ICP-MS and ICP-OES.

Direct determination of impurities in arsenic by atomic spectrometry

The present paper describes development of Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) and Electrothermal Atomization-Atomic Absorption Spectrometry (ETA-AAS) for the direct determination of fifteen common metallic and semi-conducting elements in high purity arsenic without prior separation of the major matrix. With a view to improving determination of Cd in arsenic matrix and for providing independent check on determination of few representative elements such as Cu, Cr, Mn and Ni by ICP-AES method, ETA-AAS technique also has been developed for direct determination of these elements in arsenic matrix. A number of synthetic samples have been prepared and analysed by both the techniques to validate the analytical procedures adopted here.

Saturated aqueous solution of lead chromate as a calibration reference material for Cr(vi)

A saturated solution of PbCrO4 has been proposed as a Calibration Reference Material for Cr(VI). Statistically evaluated results of Cr(VI) determination in a saturated solution of PbCrO4 by electrothermal atomization atomic absorption spectrometry (ETAAS) confirm that the found concentration of Cr(VI), (6.99 ± 0.34 μg l−1) is in complete agreement with the calculated value of Cr(VI) in that solution—7.0 μg l−1. The advantage of such a Calibration Reference Material is that the concentration of Cr(VI) is theoretically predictable on the base of solubility product constant and does not require independent determination.

Determination of lead in plants in controlling phytoremediation processes using slurry sampling electrothermal atomic absorption spectrometry

The comparative determination of lead in plant samples by two atomic spectrometric techniques is reported. At first, slurry sampling electrothermal atomisation atomic absorption spectrometry (ETAAS) was applied. The results obtained were compared with those found after a wet digestion procedure by flame atomic absorption spectrometry (FAAS) or ETAAS. The accuracy of the studied methods was checked using a certified reference material (CL − 1 CRM, Cabbage Leaves). The recovery of lead was 90% for slurry sampling ETAAS, and 86.6% for liquid sampling ETAAS. The advantages of the slurry sampling ETAAS method are the simplicity of sample preparation and very good sensitivity.