[Show abstract][Hide abstract] ABSTRACT: The on-line atomization of gold volatile species was studied and the results were compared with thermodynamic calculations in several quartz atomizers, namely: diffusion flame, flame-in-gas-shield, flame-in-plain-tube, externally heated T-tube and externally heated flame-in-T-tube. Atomization mechanism in the explored devices is proposed, where volatile species are converted to thermodynamically stable AuH at elevated temperature over 500 °C and then atomized by an interaction with a cloud of hydrogen radicals. Because of its inherent simplicity and robustness, diffusion flame was employed as a reference atomizer. It yielded atomization efficiency of 70 to 100% and a very good long time reproducibility of peak area sensitivity: 1.6 to 1.8 s µg-1 . Six and eleven times higher sensitivity, respectively, was provided by atomizers with a longer light paths in the observation volume, i.e. externally heated T-tube and externally heated flame-in-T-tube. The latter one, offering limit of detection below 0.01 µg ml-1 , appeared as the most prospective for on-line atomization. The insight into mechanism of atomization of gold volatile species, into the fate of free atoms and into subsequent analyte transfer allowed to assess possibilities of in-atomizer preconcentration of gold volatile species: it is unfeasible with quartz atomizers but a sapphire tube atomizer could be useful in this respect.
Spectrochimica Acta Part B Atomic Spectroscopy 01/2015; 103-104:155-163. DOI:10.1016/j.sab.2014.12.007 · 3.18 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A simple device for the reduction of nonspectral interferences in flame atomic absorption spectrometry is proposed. It has been reported that the use of a gas screen (GS) system together with a slotted quartz tube (SQT) enhances the residence time of analyte atoms in measurement zone even more than the SQT alone. This combination causes enhancement of sensitivity and improves the reproducibility of absorbance measurements. In addition, it protects the optical windows of the atomic absorption spectrometer. The operational mechanism of gas screen is simply applying two argon gas walls at both ends of SQT to provide an environment that is partly protected from air. This action enhances the sensitivity of measurement.In this study, interference effects of excess amounts of calcium and chromium on the measurements of Cd, Co, Cu, Pb, Mn, Ni, Se, and Zn were studied using flame AAS. The presence of both Ca and Cr cause higher absorbance values; it is suggested that this is due to formation of oxide species of Ca and Cr and as a result analyte oxide production is suppressed. Therefore, analyte free atom population and sensitivity are enhanced. This enhancement results in a positive error in measurements. For instance, presence of solely 8.0 mg L−1 of Cr or Ca for Pb as the analyte enhances the signals by 75% and 56%, respectively. When SQT or GS-SQT is used, this effect is significantly reduced.
[Show abstract][Hide abstract] ABSTRACT: Speciation of tellurium can be achieved by making use of different kinetic behaviors of Te(IV) and Te(VI) upon their reaction with sodium borohydride using hydride generation. While Te(IV) can form H(2)Te, Te(VI) will not form any volatile species during the course of hydride formation and measurement by atomic absorption spectrometry. Quantitative reduction of Te(VI) was achieved through application of a microwave assisted prereduction of Te(VI) in 6.0mol/L HCl solution. Enhanced sensitivity was achieved by in situ trapping of the generated H(2)Te species in a previously heated graphite furnace whose surface was modified using Pd or Ru. Overall efficiency for in situ trapping in pyrolytically coated graphite tube surface was found to be 15% when volatile analyte species are trapped for 60s at 300°C. LOD and LOQ values were calculated as 0.086ng/mL and 0.29ng/mL, respectively. Efficiency was increased to 46% and 36% when Pd and Ru surface modifiers were used, respectively. With Ru modified graphite tube 173-fold enhancement was obtained over 180s trapping period with respect to ETAAS; the tubes could be used for 250 cycles. LOD values were 0.0064 and 0.0022ng/mL for Pd and Ru treated ETAAS systems, respectively, for 180s collection of 9.6mL sample solution.
[Show abstract][Hide abstract] ABSTRACT: Significant improvement has been achieved for antimony determination using a slotted quartz tube (SQT) as an atom trap (AT) for in situ preconcentration and flame atomic absorption spectrometry (FAAS). The suggested technique consists of trapping analyte species during ordinary nebulization followed by releasing the collected analyte via introducing organic solvent. Procedures and analytical figures of merit have been presented for the techniques called FAAS, SQT-FAAS and finally SQT-AT-FAAS with the relevant comparisons. Analytical parameters, namely composition of the aqueous medium, sample flow rate, flame conditions, distance between burner head and SQT, sampling period and type of organic solvent and its volume have been optimized. Using SQT-AT-FAAS, a sensitivity enhancement of 369 fold has been obtained, 3 s limit of detection was 3.9 μg L− 1 when 25.0 mL of sample was collected in 4.0 min. Interference effects of some elements on antimony signal were studied.
Spectrochimica Acta Part B Atomic Spectroscopy 11/2012; 77:63–68. DOI:10.1016/j.sab.2012.09.001 · 3.18 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Carcinogenic and mutagenic properties of aflatoxin species are known in literature. Their intake over a long time period might be health-dangerous for human even at trace levels. It is well known that different foodstuffs can be contaminated by aflatoxin species through growing and storage. Due to the serious health effects, sensitive determination of aflatoxin species in any matrices related with the human being is very crucial at trace levels. In literature, there are sensitive techniques to analyze the different samples for the contents of their aflatoxin species. Each technique has some advantages and disadvantages over the other techniques. This review aims to summarize the different health effects of aflatoxin species, development of analytical techniques and applications of developed techniques in a variety of matrices.
Central European Journal of Chemistry 06/2012; 10(3). DOI:10.2478/s11532-012-0009-2 · 1.33 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Sensitivity enhancement of indium determination by flame atomic absorption spectrometry (FAAS) was achieved; using a slotted quartz tube (SQT-FAAS) and slotted quartz tube atom trap (SQT-AT-FAAS). SQT was used as an atom trap (AT) where the analyte is accumulated in its inner wall prior to re-atomization. The signal is formed after re-atomization of analyte on the trap surface by introduction of 10 μL of isobutyl methyl ketone (IBMK). Sensitivity was improved 400 times using SQT-AT-FAAS system with respect to conventional FAAS and 279 times with respect to SQT-FAAS without any collection. Characteristic concentration (C(0)) and limit of detection values were found to be 3.63 ng mL(-1) and 2.60 ng mL(-1), respectively, using a sample flow rate of 7.0 mL min(-1) and a collection period of 5.0 min. In addition, interference effects of some elements on indium signal were studied. In order to characterize indium species trapped, X-ray Photoelectron Spectrometry (XPS) was utilized and it was found that indium was collected on the inner surface of SQT as In(2)O(3). The accuracy of the procedure was checked to determine indium in the standard reference material (Montana Soil, SRM 2710).
[Show abstract][Hide abstract] ABSTRACT: The determination of inorganic arsenic species in water samples from Ankara, İzmir and Burdur was done by using hydride generation atomic absorption spectrometry (HGAAS) with controlled pH and redox chemistry for speciation of As (III) and As (V). Specific trivalent arsenic is determined in water samples prepared in 0.10 mol L HCl with the usage of 1.0% (w/v) sodium tetrahydroborate (NaBH4) as reductant solution. The determination of total arsenic is done by reduction of As (V) to As (III) by means of 0.50% (w/v) ascorbic acid and 1.0% (w/v) potassium iodide (KI) in the 0.10 mol L HCl in water samples. For this purpose, by using 0.1 mol L HCl at which As (V) did not give any signal while As (III) gave a signal in this acidity. Furthermore 1.0% (w/v) KI and 0.50% (w/v) ascorbic acid were added in water samples which were prepared in the 0.10 mol L HCl. The detection limit for this study is 0.29 ng mL for As (III) and linear range of calibration plot is in the range from 1.6 to 16 ng mL. In order to check the accuracy of the method, certified reference material, CRM-TMDW trace metals in drinking water, µg L was employed; the result was found to be in good agreement with the certified value at the 95% confidence level.
International Journal of Environmental Analytical Chemistry 09/2011; DOI:10.1080/03067319.2010.550004 · 1.30 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Scleroderma verrucosum, Stropharia coronilla, Lactarius deterrimus, Chroogomphus rutilus, Russula delica, Laccaria laccata, Clitocybe odora var. alba, Lyophyllum decastes, Coprinus comatus, Helvella leucomelaena, Melanoleuca cognata, Melanoleuca cognata, Paxina acetabulum, Clitocybe vermicularis, Sarcosphaera crassa, Rhizopogon roseolu and Thelephora caryophyllea were collected from different localities in Muğla-Yatağan region of Turkey. Their trace metals concentrations were determined by ICPOES after microwave digestion. The results were 0.37 ± 0.01-5.28 ± 0.21 for cadmium, 467 ± 19-3,280 ± 131 for iron, 0.69 ± 0.03-9.15 ± 0.37 for lead, 18.70 ± 0.75-67.10 ± 2.68 for selenium, 75 ± 3-213 ± 8 for zinc and 0.15 ± 0.01-0.55 ± 0.01 for mercury (as μg/g). The detection limits for ICPOES were found as 0.25 for Cadmium, 0.2 for iron, 0.1 for lead, 0.5 for selenium, 0.2 for zinc and 0.03 for mercury (as mg L(-1)). The Relatively Standard Deviations (R.S.D.) were found below 4.0%. The accuracy of procedure was confirmed by certified reference material.
Bulletin of Environmental Contamination and Toxicology 09/2011; 87(3):276-81. DOI:10.1007/s00128-011-0357-1 · 1.26 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The generation of an analytically useful volatile form of Au has been studied. The flow injection generation was performed in a dedicated generator consisting of a special mixing apparatus and gas-liquid separator design in the presence of surfactants (Triton X-100, Antifoam B) and diethyldithiocarbamate. The on-line atomization in the quartz tube multiatomizer for atomic absorption (AAS) detection has been employed as the convenient atomization/detection means. The optimization of generation and atomization conditions resulted in an analytical procedure yielding the detection limit of 17 ng ml-1 and a very good long range reproducibility of the analytical signal. A 198,199Au radioactive indicator of high specific activity together with AAS measurements was used to track quantitatively the transfer of analyte in the course of generation and transport to the atomizer and to determine the generation efficiency of 11.9 +/- 0.1% at the Ar carrier flow rate optimized for the multiatomizer of 240 ml min-1. The efficiency was twice as high at the Ar carrier flow rate of 600 ml min-1. In situ trapping in GF for AAS was explored as an alternative to the on-line atomization. The detection limit of 3.0 ng ml-1 was achieved even though the Ar flow rate optimum for trapping (115 ml min-1) was too low for efficient generation: the overall efficiency of generation and trapping was 1.11 +/- 0.03%. Transmission electron microscopy measurements proved the presence of Au nanoparticles of diameter of approximately 10 nm and smaller transported from the generator by the flow of carrier Ar
[Show abstract][Hide abstract] ABSTRACT: Speciation studies are much more important than total element determination because toxicity of many elements depends on their chemical forms. Nobody can claim that a foodstuff is very dangerous to eat by determining total arsenic due to the possibility that the arsenic could be present in non-toxic forms. Hence, speciation studies are crucial in any matrix relevant to human beings.Trace-element speciation requires sufficiently sensitive procedures to monitor each species at trace levels. One way to increase the sensitivity for elements forming volatile species is coupling high-performance liquid chromatography (HPLC) with chemical-vapor generation (CVG). This review aims to highlight not only development of HPLC-CVG techniques for ultratrace-elemental speciation in a variety of matrices but also their application. In addition, we discuss the advantages and the disadvantages of these techniques.
[Show abstract][Hide abstract] ABSTRACT: We investigated the possible relationship between boron exposure and prostate cancer (PCa) for men living and being employed at boron mines in villages with rich boron minerals. Out of 456 men studied, 159 were from villages with rich boron sources and boron levels in drinking water of >1 mg L(-1) and these men formed the study group, while 63 from villages with rich boron sources and boron levels in drinking water of <1 mg L(-1) were enrolled into control group 1. A further 234 subjects from other villages with no boron mines were considered as control group 2. Prostate specific antigen (PSA) levels could be obtained from a total of 423 men. Urinary boron concentration as an indicator of boron exposure in 63 subjects, prostatic volumes by transrectal ultrasonography in 39 subjects, and prostatic biopsies in 36 subjects were obtained for study and control groups. The daily boron exposure was calculated according to urinary boron levels. Although there was no significant difference among the groups in terms of total PSA levels, the number of subjects with tPSA ≥2.5 and tPSA ≥10.0 ng dL(-1) prostatic volumes in men whose prostates were biopsied (p < 0.012) was significantly lower in the study group as compared with those in the control group 2. These results suggested that high exposure to boron might have an implication within the prostatic cellular processes related to hyperplasia and carcinogenesis, even though we did not find a statistically significant association between PCa and boron exposure.
Biological trace element research 03/2011; 144(1-3):49-57. DOI:10.1007/s12011-011-9023-z · 1.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Determination of the trace elements in a variety of environmental samples is of great importance. Most elements, including iron, calcium, and selenium, are crucial for the regulation of human mechanisms, and many others, like lead and cadmium, are toxic even at trace levels. Some elements, like selenium, have a narrow margin of safety. Hence, determination of elements at trace levels is crucial in any matrix related to humans. Trace element determination requires sufficiently sensitive procedures to monitor trace levels. This review aims to highlight not only the development in instrumentation for ultratrace element determination in variety of matrices but the application of developed techniques. Advantages and disadvantages of the techniques are also discussed.
[Show abstract][Hide abstract] ABSTRACT: The determination of bismuth requires sufficiently sensitive procedures for detection at the microg L(-1) level or lower. W-coil was used for on-line trapping of volatile bismuth species using HGAAS (hydride generation atomic absorption spectrometry); atom trapping using a W-coil consists of three steps. Initially BiH(3) gas is formed by hydride generation procedure. The analyte species in vapor form are transported through the W-coil trap held at 289 degrees C where trapping takes place. Following the preconcentration step, the W-coil is heated to 1348 degrees C; analyte species are released and transported to flame-heated quartz atom cell where the atomic signal is formed. In our study, interferences have been investigated in detail during Bi determination by hydride generation, both with and without trap in the same HGAAS system. Interferent/analyte (mass/mass) ratio was kept at 1, 10 and 100. Experiments were designed for carrier solutions having 1.0M HNO(3). Interferents such as Fe, Mn, Zn, Ni, Cu, As, Se, Cd, Pb, Au, Na, Mg, Ca, chloride, sulfate and phosphate were examined. The calibration plot for an 8.0 mL sampling volume was linear between 0.10 microg L(-1) and 10.0 microg L(-1) of Bi. The detection limit (3s/m) was 25 ng L(-1). The enhancement factor for the characteristic concentration (C(o)) was found to be 21 when compared with the regular system without trap, by using peak height values. The validation of the procedure was performed by the analysis of the certified water reference material and the result was found to be in good agreement with the certified values at the 95% confidence level.
[Show abstract][Hide abstract] ABSTRACT: An electrically heated tungsten coil was used as a trap in the determination of antimony. The technique consists of three steps. Initially, SbH3 is formed by hydride generation procedure; then the analyte species in vapor form are transported to W-coil trap heated at 370 °C. Following the preconcentration step, the trap is heated to 895 °C; analyte species are revolatilized and transported to the flame-heated quartz atom cell where atomization and the formation of signal take place. The experimental parameters were optimized both for trap and no-trap studies. The most important experimental parameters are concentrations of HCl and NaBH4 solutions, H2 and Ar gas flow rates, and collection and revolatilization temperatures of W-coil. Accuracy was tested using a certified reference material, waste water EU-L-1. Limit of detection for the system is 16 ng l− 1 using a sample of 36 ml collected in 4.0 min. Enhancement factor in sensitivity was 17.
Spectrochimica Acta Part B Atomic Spectroscopy 08/2008; 63(8-63):875-879. DOI:10.1016/j.sab.2008.03.021 · 3.18 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A novel analytical technique was developed where gaseous hydrogen selenide formed by sodium tetrahydroborate reduction is transported to and trapped on a resistively heated gold-coated W-coil atom trap for in situ preconcentration. Gold coating on W-coil was prepared by using an organic solution of Au. The atom trap is held at 165 °C during the collection stage and is heated up to 675 °C for revolatilization; analyte species formed are transported to an externally heated quartz T-tube where the atomization takes place and the transient signal is obtained. The carrier gas consisted of 112.5 ml min−1 Ar with 75 ml min−1 H2 during the collection step and 112.5 ml min−1 Ar with 450 ml min−1 H2 in the revolatilization step. The half width of the transient signal obtained is less than 0.5 s. The RSD for the measurements was found to be 3.9% (n=11) for 0.10 µg l−1 Se using peak height measurements.The calibration plot for 27.0 ml of sample collected in 4.0 min using a flow rate of 6.75 ml min−1 was linear between 0.13 and 2.0 µg l−1 of Se. The limit of detection (3 s) is 39 ng l−1.The enhancement factor for the characteristic concentration (Co) was found to be 20.1 when compared to conventional hydride generation atomic absorption spectrometry system without trap. In order to check the accuracy of the method, standard reference material, natural water NIST 1640 was employed; the result was found to be in good agreement with the certified value at the 95% confidence level.
Spectrochimica Acta Part B Atomic Spectroscopy 08/2008; 63(8):856-860. DOI:10.1016/j.sab.2008.03.020 · 3.18 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This article maybe used for research, teaching and private study purposes. Any substantial or systematic reproduction, re-distribution, re-selling, loan or sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.
Phosphorus Sulfur and Silicon and the Related Elements 10/2007; 18212(12):2861-2880. DOI:10.1080/10426500701540431 · 0.56 Impact Factor