Graphite Furnace Atomic Spectrometry Research Articles

Levels of toxic metals and trace elements in autopsy liver tissue samples

The aim of the study is to determine the levels of toxic metals (cadmium and lead) and trace elements (zinc and copper) in the liver tissues of autopsy cases in Ankara and to evaluate the statistical relationship of these metals with subjects’ physical properties, smoking status, occupational exposure and environmental factors. Results are expected to establish the average burden of involved metals in liver tissue of Turkish population. Hepatic trace elements and toxic metal levels were assessed in 119 autopsy cases. Digestion procedure for liver tissues was carried out using a Mars Xpress microwave system (CEM, Matthews, USA) with PTFE microwave digestion vessels. Lead and cadmium were analyzed by Graphite Furnace Atomic Spectrometry; copper and zinc were analyzed by Flame Atomic Absorption Spectrometry. Average liver levels of metals and trace elements were found 29.5 µg/g, 216 µg/g, 0.39 µg/g and 4.38 µg/g dry weight for copper, zinc, lead and cadmium, respectively. Copper and lead levels were found higher in men. There was a significant decrease in copper levels with age. Lead levels in city dwellers were significantly higher and there was no correlation between metal levels and occupations of the individuals. Significant increase in copper, lead and cadmium were observed in smokers’ liver tissues. All metal levels were compared with each other and positive correlation was found between zinc-copper, lead-zinc and copper-zinc levels (p˂0.01). In Turkey, it is the first study which gives liver tissue levels of trace elements and heavy metals of autopsy samples in a city which has a median-scale industrial development.

Effects of age, gender, BMI, settlement and smoking on lead and cadmium accumulation in heart tissue

Cadmium (Cd) and lead (Pb) are well-known risk factors for peripheral arterial and some other cardiovascular diseases. The aim of the study was to determine the level of both toxic metals, in the human heart tissue and compare the accumulation to their age, gender, body mass index, living environment and smoking habit. Heart tissues of the 112 autopsy cases, representing a sample set of population living in capital city of Turkey: Ankara Province (both in city center and suburban), were collected from Turkey Ministry of Justice, Council of Forensic Medicine in Ankara Branch. Lead and cadmium analysis was carried out by Graphite Furnace Atomic Spectrometry technique. Cd/Pb results and individuals’ information were assessed by SPSS statistically. Average value of Pb was found as 1374.99±237.01ppb and Cd was found as 287.54±66.43ppb in all heart tissue samples. Consideration of metal levels in autopsy heart tissues by age, statistically significant positive correlation in Cd was observed (p

Determination of Er3+ Ion at Nano Level Based on Newly Synthesized Schiff Base As a Neutral Carrier By Coated Graphite Electrode

The rare earth elements (REEs) are mainly of two series Lanthanides and Actinides. Despite of their name REEs are not so rare in environment, they widely distributed in throughout the earth’s crust in low concentration. The REEs have significant industrial application as competitive to transition elements and wide application have been found in bioinorganic, inorganic chemistry. Erbium is mainly used as laser beams to resurfacing skin, transdermal drug delivery, transdermal peptide delivery, skin vaccination and enhances the RNA delivery. It is estimated that the erbium concentration of the earth’s crust reaches 24 ppm. The commercial sources of erbium are monazite and bastnasite. Even though the conclusion of the investigators, the rare earth elements are considered as low acute toxicity rating, these causes several problems to living species. Due to their enhanced discharge, toxic properties and other adverse effects, determination of erbium is essential in a variety of environmental samples.A number of instrumental techniques such as second order derivative spectrophotometry, third-derivative spectrophotometry, X-ray fluorescence, graphite furnace atomic spectrometry techniques, inductively coupled plasma mass spectrometry, rutherford backscattering spectrometry and spectrophotometric determination are available for its estimation. These methods provide accurate determination of erbium content but involve large infrastructure backup and support of expertise. We found ion-selective electrode to overcome these problems. Ion-selective electrodes are electrochemical ideal sensors in many respects for use in the analysis of industrial and environmental samples.Plasticized membranes using N-(-3-((thiazol-2-ylimino)methyl)benzylidene)thiazol-2-amine (S1) and 5-((-3-((5-mercapto-1,3,4-thiadiazol-2-ylimino)methyl)-benzylidene)amino)-1,3,4-thiadiazole-2-thiol (S2) have been prepared and explored as Er3+ selective electrodes. Effect of various plasticizers viz. dibutylphthalate (DBP), tri-n-butylphosphate (TBP), dioctylphthalate (DOP), acetophenone (AP), 1-chloronapthalene (1-CN), o-nitrophenyloctylether (o-NPOE), and anion excluders viz. sodium tetraphenylborate (NaTPB) and potassium tetrakis-p-(chlorophenyl)borate (KTpClPB) was studied in detail and improved performance was observed. Optimum performance was observed for the membrane electrode having a composition of S2: PVC: o-NPOE: KTpClPB in the ratio of 4: 38: 55: 3 (w/w, mg). The performance of the polymeric membrane electrode (PME) based on S2 was compared with coated graphite electrode (CGE). The electrodes exhibit Nernstian slope for Er (III) ions with limit of detection of 5.4 × 10-8 mol L−1 for PME and 6.1 × 10-9 mol L−1 for CGE. The response time for PME and CGE was found to be 12 s and 9 s respectively. The potentiometric responses are independent of the pH of the test solution in the pH range 4.0-9.0 for PME and 3.0-9.5 for CGE. The CGE could be used for a period of 7 weeks. The practical utility of the CGE has been demonstrated by its usage as an indicator electrode in potentiometric titration of EDTA with Er (III) solution and determination of F- ion in mouthwash solution. The proposed electrode was also successfully applied to the determination of Er3+in water, binary mixtures. Table 1. Response characteristics of Er3+ ion selective electrodes based on PME and CGE. PropertiesElectrode ResponsePMECGEWorking concentration range (mol L-1)7.9 × 10-8 - 1.0 × 10-1 9.4 × 10-9 - 1.0 × 10-1 Detection limit (mol L-1)5.4 × 10-8 6.1 × 10-9 Slope (mV decade-1 of activity)19.8 ± 0.419.6 ± 0.3Response time (s)129pH range4.0-9.03.0-9.5Fig. 1. Structure of ligands N-(-3-((thiazol-2-ylimino)methyl)benzylidene)thiazol-2-amine (S1) and 5-((-3-((5-mercapto-1,3,4-thiadiazol-2-ylimino)methyl)-benzylidene)amino)-1,3,4-thiadiazole-2-thiol (S2)

Total arsenic and selenium analysis in Marcellus shale, high-salinity water, and hydrofracture flowback wastewater

Trace levels of arsenic and selenium can be toxic to living organisms yet their quantitation in high ionic strength or high salinity aqueous media is difficult due to the matrix interferences which can either suppress or enhance the analyte signal. A modified thiol cotton fiber (TCF) method employing lower flow rates and centrifugation has been used to remove the analyte from complex aqueous media and minimize the matrix interferences. This method has been tested using a USGS (SGR-1b) certified reference shale. It has been used to analyze Marcellus shale samples following microwave digestion as well as spiked samples of high salinity water (HSW) and flow back wastewater (WRF6) obtained from an actual gas well drilling operation. Quantitation of arsenic and selenium is carried out by graphite furnace atomic spectroscopy (GFAAS). Extraction of arsenic and selenium from Marcellus shale exposed to HSW and WRF6 for varying lengths of time is also reported.

Influence of Uranium, Thorium, and Zirconium Matrices on Silver Absorbance in Graphite Furnace Atomic Spectrometry (GFAAS)

Influence of Uranium, Thorium, and Zirconium Matrices on Silver Absorbance in Graphite Furnace Atomic Spectrometry (GFAAS)

Topochemical Speciation of Intercalated Palladium in Graphite by Valence Band X-ray Spectrometry in the Electron Microprobe

The binding state of palladium was studied within the frame of an investigation on the mechanism of analyte fixation during the pyrolysis step in graphite furnace atomic spectrometry. One approach was the determination of the palladium intercalated in the pyrolytic coating of the graphite tube. Due to the low concentrations of intercalated palladium in the pyrolytic coating, precise determination of the shift of certain X-ray lines was chosen. From several investigated valence state sensitive X-ray transitions, the Pd Lbeta2/15 (L3-N4,5) line shift was the one best determinable. The measured line shifts are in the range of -0.14 to 0.71 eV at line widths of 13 eV (fwhm) and a line energy of 3.1729 keV. These very small line shifts were determined by electron probe microanalysis. The detection of the small line shifts was performed with a new method-by evaluation of the change of the intensity in the flanks of the X-ray line. The measurements yielded the following results: inside the pyrolytic graphite, the palladium is distributed inhomogeneously in the form of clusters or islands and in the form of particles on the surface of the pyrolytic graphite. The differentiation between particles and clusters is a very practical one: as long as a particle can be seen in the SEM we talk of particles. Often, however, Pd is detected in an area on the tube or platform surface without detection of a particle. Hence, it can be assumed that the Pd is present in the form of clusters which might even be intercalated in the uppermost graphite layers. The valence state inside these clusters does not appear to be uniform. It can be interpreted as a mixture of Pd with PdO in the center of the clusters or particles (positive peak shift) and of Pd bound to the graphite (strong negative peak shift). On the basis of these observations, a way is proposed to determine how activated Pd atoms in intercalated Pd domains are forming strong covalent bonds to analytes. These bonds are responsible for the analyte fixation of even very volatile analytes.

The determination of molybdenum in water and biological samples by graphite furnace atomic spectrometry after polyurethane foam column separation and preconcentration

A system for molybdenum separation and enrichment aiming its determination in water and biological samples by graphite furnace atomic absorption spectrometry (GFAAS) is proposed. The procedure is based on the sorption of the molybdenum (VI) thiocyanate complex onto a mini-column packed with polyurethane foam (PUF). The elution is accomplished by a 3.0 mol l −1 nitric acid solution. Flow variables were optimized and an enrichment factor of 10 as well as a limit of detection (LOD) (3 s) of 0.08 μg l −1 in the sample solution were achieved. The coefficient of variation showed values of 3 and 2% for molybdenum solutions of 2.0 and 10.0 μg l −1, respectively. The accuracy of the method was confirmed by the good concordance between found and certified values in the analysis of certified reference materials (CRMs) (CASS-3 Nearshore Seawater, NIST 1547 Peach Leaves, NIST 1515 Apple Leaves and NIST 1572 Citrus Leaves). The procedure was also applied for the molybdenum determination in mineral waters as well as in produced water samples. The results obtained for the mineral water samples compared well with those obtained by ICP-MS. Concerning the produced water samples, in spite of their large salinity, recoveries of 90 to 120% at the 1 μg l −1 were observed.

Separation and preconcentration of chromium speciation on chitosan and determination by graphite furnace atomic absorption spectrometry

A novel method for the separation and preconcentration of chromium speciation with chitosan and determination by graphite furnace atomic spectrometry (GFAAS) has been developed. Adsorption rates of chitosan for CrVI and CrIII were 98 and 20% at pH 3, respectively. CrVI was selectively eluted off from chitosan with 5 ml of 0.1 mol L−1 sodium hydroxide and determined by GFAAS. Accordingly, contents of CrIII were obtained by the determination of total chromium after CrIII in water samples had been transformed into CrVI. The detection limit (3σ, n = 10) for CrVI was 0.0468 µg L−1 and the relative standard deviation less than 7.8% at the 0.2 µg L−1 level. The method was applied to environmental water samples with recoveries of between 92–105%.

Determination of erbium and neodymium dopants in bismuth tellurite optical crystals by graphite furnace atomic spectrometry techniques

Application of concentrated HCl as a solvent and triammonium citrate (TAC) as a chemical modifier is advantageous for the determination of Er and Nd dopants in bismuth tellurite (Bi2TeO5) single crystals by graphite furnace atomic absorption spectrometry (GFAAS). The use of mini-flow of the internal gas, instead of gas stop, results in better precision at a price of a relatively small decrease in sensitivity. By evaluating integrated absorbance (Aint) signals for the GFAAS measurements (in the presence of matrix and TAC additive), characteristic mass values of 42 and 320 pg, and a limit of detection (LOD) of 4.9 and 131 μg l−1 are found for Er and Nd, respectively. These LOD data correspond to 0.78 μg g−1 Er and 21 μg g−1 Nd in the solid samples. The calibration curves are linear up to 0.33 and 2.9 mg l−1 concentrations in the solutions of Er and Nd, respectively. The ratio of the Aint signals of Er and Nd under gas stop and mini-flow were found near constant (1.34) with and without the matrix plus TAC. According to the vaporisation studies by graphite furnace electrothermal vaporisation inductively coupled plasma atomic emission spectrometry (GF-ETV-ICP-AES), the vaporisation of Bi and Te components of the solid Bi2TeO5 can be completed at 1200°C in a relatively short time, ensuring a preconcentration for the Er and Nd dopants, which do not vaporise below 2200°C in an argon atmosphere. On the other hand, fast vaporisation can be performed for the analytes at 2200°C with the use of CCl4 vapour (∼0.5 v/v%) in the internal furnace gas (Ar). It was estimated for the Er analyte that by applying 10 mg of solid sample in the GF-ETV device (dispensed into a graphite sample boat) and using a two-step heating procedure (prevaporisation of the matrix in argon and vaporisation of the analyte in a chlorinating atmosphere), the lower limit of the quantitative determination with the ICP-AES method would be approximately one order of magnitude better than attainable with the GFAAS method based on dissolution.

Serum selenium concentration of a healthy northwest Spanish population.

Selenium (Se) is an essential element, cofactor for glutathione peroxidase (GSHPx) activity, whose deficiency may induce modifications in the cellular antioxidative status and induce the appearance of different diseases. Current views suggest that a serum Se concentration inferior to 45 micrograms/L may correlate with an increased risk of coronary hearth diseases, coronary atherosclerosis and cancer. Since the Se concentration in human blood varies between geographical areas, we initiated a study to evaluate the Se status in the general healthy population of Barcelona. Serum Se concentration was investigated in a random sample of 150 subjects (age range 18-70 yr) by graphite furnace atomic spectrometry (FLAAS). L'vov platform, Zeeman background correction, and other specifications of stabilized temperature platform furnace (STPF) concept were followed. The results show that in the general population of Barcelona, Se serum concentration ranges between 60 and 106 micrograms/L (X = 80.7 +/- 10 micrograms/L). These values can be considered within the safe limits, since no subject was found with a concentration lower than the threshold of 45 micrograms/L.

Leachability of Arsenic from Field Containers Filled With Plant Growth Medium Amended With Biosolids Compost

The leaching of arsenic (As) from plant growth medium, admixed with different proportions of composted biosolids in field containers, was determined over a four-month period. Eight-week-old perennial flowers, Coreopsis grandiflora L, were transplanted in the field in 2-L containers filled with plant growth media. The treatments were replicated three times and rainfall was supplemented to supply 2 cm of water per day. Water percolating through potted plant containers was collected biweekly and analyzed for As using graphite furnace atomic spectrometry. The concentrations of As in the leachates increased with increasing proportions of compost in the medium and decreased with time of leaching, generally remaining below the drinking water standard of 50 μg/L after two months. Leaching of As occurred at a rapid rate initially but then continued at a slow rate. Compared to other metals of concern, as Cd, Cr, Ni and Pb, As in the compost appeared more mobile.

The Influence of Temperature on Absorbance in Graphite Furnace Atomic Absorption Spectrometry. I: General Considerations

The influence of a temperature ramp on the absorbance in graphite furnace atomic spectroscopy has been investigated with the use of a computer simulation of the absorption process. For increasing temperature, the absorbance will increase for low values of the damping constant at constant pressure and all values of the damping constant at constant volume. For large values of the damping constant at constant pressure (the presumed real situation), the absorbance decreases with increasing temperature due to the narrowing of the collisional profile. Hyperfine structure diminishes the change in absorbance within limits. The evaluation of the number density of analyte for temperatures (times) other than the peak maximum temperature could be in error if the peak maximum absorbance of a GFAAS peak is used to derive the number densities at the other temperatures. In effect, the relative absorbances on the peak in GFAAS are not totally representative of the relative atom release and removal peak. The presence of multiple ground states can, under certain circumstances, improve the absorbance-atom density relationship between the peak maximum absorbance and other absorbances on the peak. The temperature ramp has no deleterious effect on the analytical capabilities of GFAAS when the effect of temperature on absorbance is considered.

Direct determination of barium in sea and estuarine water by graphite furnace atomic spectrometry

Direct determination of barium in sea and estuarine water by graphite furnace atomic spectrometry