1,720,961 research outputs found
Development of a New Sensitive Method for Lead Determination by Platinum-Coated Tungsten-Coil Hydride Generation Atomic Absorption Spectrometry
No full textA novel very sensitive and rapid analytical method was improved where gaseous lead formed was transported to and trapped on an externally heated platinum-coated tungsten-coil atom trap for in situ preconcentration. The analytical performance of the developed method with the graphite furnace atomic absorption spectrometry (GFAAS) method was compared. All critical parameters affecting the performance of both methods were optimized. The limit of quantitation (LOQ) was found as 11.0 ng L-1 and the precision was 2.3% in terms of percent relative standard deviation (RSD%). Characteristic concentration (Co) of the developed trap method was indicating a 32.5-fold enhancement in sensitivity compared to the GFAAS method. In order to investigate the surface morphology of the W-coil, scanning electron microscope-energy-dispersive X-ray (SEM-EDS) analyzes were performed. The accuracy of the trap method was tested by certified reference materials: NIST SRM 1640a (the elements in natural water) and DOLT:5 (dogfish liver). Interferences from other hydride-forming elements were investigated. Application of the trap method was demonstrated by the analysis of some drinking water and fish tissue samples. The t test was applied to drinking water samples, and the results indicated that there was no statistically significant error
Speciation and determination of inorganic selenium species in certain fish and food samples by gold-coated W-coil atom trap hydride generation atomic absorption spectrometry
No full textA very sensitive, selective, rapid and easy gas-phase preconcentration based method is presented for the determination and speciation of inorganic selenium in chicken meat, poultry eggs, mullet fish (Mugil Cephalus) and sea bass fish (Dicentrarchus Labrax) samples. Gold-coated W-coil atom trap was used to increase the sensitivity of conventional HG-AAS. LOD and LOQ values were calculated to be 0.021 μg/L and 0.070 μg/L, respectively. RSD% was found as 3.24. The sensitivity was increased 20 times more with the method used in the current study than the HG-AAS method. The interference effects of other metals on Se signal were significantly reduced by trap. SEM and EDX images of both bare and gold coated W-coil atom trap were screened. In order to check the accuracy of the method, "DOLT-5: Dogfish Liver" standard reference material was used and there was a good agreement between certified and found values at the 95% confidence level
Ultra-trace determination of mercury by platinum-coated tungsten coil trapping cold vapour atomic absorption spectrometry
No full textWithin the scope of this study, a simple, highly sensitive and rapid trapping method for the determination of mercury (Hg) was developed. In this method, the surface of the tungsten coil (W-coil) was coated with platinum using the electrolytic deposition technique. Scanning electron microscopy-energy-dispersive X-ray analyses were performed to examine the surface morphology of Pt-coated W-coil. During the experiment, firstly, Hg vapour generated by tetrahydroborate, used as a reducing agent, was efficiently trapped on the Pt-coated W-coil at collection temperature in hydrochloric acid medium. Subsequently, Hg trapped on the surface of the Pt-coated W-coil was revolatilised by the effect of releasing-stage gases at the optimised releasing temperatures and transported to quartz T-tube atomiser. The experimental conditions have been optimised. Under the optimised conditions, a limit of detection (LOD) of 8.8 ng L-1 was obtained using three times the standard deviation of blank values using Pt-coated W-coil trap cold vapour atomic absorption spectrometry (CVAAS) system. The precision of the measurements was evaluated by relative standard deviation of 4.4%, which is obtained by 11 consecutive measurements of reagent blanks for a collection volume of 6.83 mL corresponding to 90 s collection. The enhancement factors for both LOD (3 s) and characteristic concentration (C-o) were found to be 5.09 and 5.02 when compared with the regular CVAAS system without trap. The accuracy of the proposed method was evaluated by analysing BCR 146 R (Sewage sludge), RTC (Sandy Loam 7), ERM-BD151 (skimmed milk powder) and NIST 1641e (mercury in water) certified reference materials (CRMs). There was a good agreement between certified and found values for all CRMs. The results of the application of the developed method in seawater showed the spike recovery ranges from 94.2% to 102.4%
Ultra-Trace Determination of Arsenic by Platinum-Coated Tungsten Coil Hydride Generation (HG) Atomic Absorption Spectrometry (AAS)
No full textA simple, rapid, and sensitive method for the determination of ultra-trace arsenic (III) is reported based on in situ trapping and revolatilization on a platinum (Pt) coated tungsten (W) coil atom trap. First, the analyte species in vapor form were transported by a mixture of Ar and H-2 and trapped on the Pt-coated W-coil heated at 60 degrees C. Next, in the releasing step, the trap was resistively heated to 950 degrees C; the analyte species are revolatilized and transported to the quartz tube atomizer. The NaBH4 concentration, NaOH concentration, HCl concentration, trapping and releasing temperature, trapping time, and hydrogen and argon gas flow rates were optimized. Using these conditions, a limit of detection of 16 ng L-1 was obtained. The precision was evaluated by relative standard deviation corresponding to 4.8% at 1.0 mu g L-1 (n = 11). The surface of the W-coil trap was coated with Pt using electrolytic deposition. Scanning electron microscopy-energy dispersive X- ray (SEM-EDX) analyses were performed to control the surface morphology of the trap. The same trap may be used for at least 350 atomization cycles without losing sensitivity. The accuracy of the proposed method was evaluated by analyzing NIST CRM 1640a (Trace Elements in Natural Water), EnviroMAT (Drinking water), and CRM-023 (Sandy Loam 7) certified reference materials. The measurements of the certified reference materials were in good agreement with the certified values at the 95% confidence level. The developed method was applied to the determination of As in drinking water samples from Mugla province
Determination and speciation of selenium in water samples collected from Mugla (Turkey) province by hydride generation atomic absorption spectrometry
No full textIn this work, determination of selenium in various water samples was done by using hydride generation atomic absorption spectrometry. The most appropriate values of HCl concentration, NaBH4 concentration, NaOH concentration, flow rate of argon and flow rate of waste solution were determined. The optimum concentration of the HCl, NaBH4 and NaOH solutions were found to be 7.0 mol L-1, 1.0% and 0.75%, respectively. The optimum flow rate of Ar gas and waste solution were also found to be 100.9 mL min(-1) and 4.0 mL min(-1), respectively. Values of LOD and LOQ were calculated separately for total Se and Se(IV). LOD and LOQ values were calculated 0.56 mu g L-1, 1.87 mu g L-1 for total Se and 0.72 mu g L-1, 2.40 mu g L-1 for Se(IV), respectively. The precision was evaluated by relative standard deviation (RSD%) was found to be 3.5% for total Se and 3.1% for Se(IV) (n = 11). A standard reference material (NIST 1643e) was used in order to check the accuracy of the proposed method. There was a good agreement between certified and found values for standard reference material. The method was applied to the analysis of total Se and Se(IV) concentrations in tap water samples collected from the various regions of Mugla. Proposed method showed spike recovery ranges from 92% to 116% in water samples
Determination and speciation of methyl mercury and total mercury in fish tissue samples by gold-coated W-coil atom trap cold vapor atomic absorption spectrometry
No full textA sensitive analytical technique was developed where gaseous mercury formed by sodium tetrahydroborate reduction is transported to and trapped on a resistively heated gold-coated Tungsten-coil atom trap for in situ preconcentration. This technique was applied successfully for determination and speciation of methyl mercury and total mercury in some fish tissue samples (liver, muscle and gill) obtained from Muğla province. The analytical parameters were optimized both for trap and no-trap studies. Under the optimized conditions, a limit of detection (LOD) of 6.0 ng/L was obtained. The precision was evaluated by relative standard deviation (RSD%) corresponding to 4.1% (n = 11). Accuracy of the proposed method was evaluated by analyzing “DOLT:5 Dogfish Liver”, “NIST SRM 1640a Trace elements in natural water” and “NIST 1946 Lake Superior fish tissues”. The measurements of the certified reference materials were in good agreement with the certified values at the 95% confidence level
Removal of Ni(II), Cu(II), Pb(II), and Cd(II) from Aqueous Phases by Silver Nanoparticles and Magnetic Nanoparticles/Nanocomposites
No full texthe intake of heavy metals into the body, even at very low concentrations, may cause a decrease in central nervous system functions; deterioration of blood composition; and liver, kidney, and lung damage. Therefore, heavy metal ions must be removed from water. In this study, silver, magnetic iron/copper, and iron oxide nanoparticles were synthesized using Lathyrus brachypterus extract and then Fe/Cu-AT, Fe3O4-AT, Fe/Cu-CS, and Fe3O4-CS magnetic nanocomposite beads were synthesized using alginate and chitosan. The removal of Cd(II), Pb(II), Ni(II), and Cu(II) ions from aqueous phases using synthesized nanoadsorbents was investigated by single and competitive (double and quaternary) adsorption techniques. The kinetic usability of the magnetic iron oxide chitosan (Fe3O4-CS) nanocomposite beads with the highest removal efficiency was evaluated. Based on experimental results, the order of removal was found to be 98.39, 75.52, 51.54, and 45.34%, and it was listed as Pb(II) > Cu(II) > Cd(II) > Ni(II), respectively. The Dubinin-Radushkevich, Freundlich, Langmuir, and Temkin isotherm models were used, and experimental results revealed that the experimental data fit the Langmuir model better. The maximum adsorption capacities (qm) obtained from the Langmuir isotherm model of Fe3O4-CS were found to be 8.71, 23.75, 18.57, and 12.38 mg/g for Ni(II), Pb(II), Cu(II), and Cd(II) ions, respectively. When the kinetic data were applied to the Lagergren, Ho-McKay, and Elovich models, it was observed that the adsorption kinetics mostly conformed to the Ho-McKay second-order rate equation. The binary and quaternary competitive adsorption data showed that Fe3O4-CS were selective toward Cu(II) and Pb(II). The reusability of the Fe3O4-CS nanoadsorbent was performed as three cycles with the same concentration. The adsorption capacities were found to be 95.81, 70.65, 50.50, and 42.75%, in turn for Pb(II), Cu(II), Cd(II), and Ni(II) ions after three cycles, which revealed that the Fe3O4-CS nanoadsorbent can be used after three cycles without losing its efficiency
Development of a Sensitive Method for Cadmium Determination in Fish Tissue and Drinking Water Samples by FAAS Using SQT In Situ Atom Trapping
No full textA sensitive and robust trap method was developed for the determination of cadmium (Cd) by using a slotted quartz tube. Using this method at a sample suction rate of 7.4 mL/min for 4.0 min collection, a 1467-fold increase in sensitivity was obtained compared to the flame atomic absorption spectrometry method. Under the optimized conditions, a limit of detection of 0.075 ng mL-1 was obtained for the trap method. The interference effects of hydride-forming elements, transition metals, and some anions on the Cd signal were investigated. The developed method was evaluated by analyzing "Sewage Sludge-industrial origin (BCR no: 146R)", "NIST SRM 1640a Trace elements in natural water", and "DOLT: 5 Dogfish Liver". There was a good agreement between the certified and found values at the 95% confidence level. This method was applied successfully for the determination of Cd in drinking water and some fish tissue samples (liver, muscle, and gill) obtained from Muğla province
EVALUATION OF TRACE METAL CONTENTS IN MUSHROOM SAMPLES FROM AZDAVAY DISTRICT, KASTAMONU, TURKEY
No full textMantarlar, önemli bir amino asit, protein ve lif kaynağı oldukları için popüler bir besindir, ancak substrattan metal biriktirme kapasiteleri yüksektir. Bu çalışmada Kastamonu Bölgesi, Azdavay'da orijinal olarak bulunan 21 mantar türünün 5 eser metal (Fe, Cr, Zn, Pb, Se) içeriği atomik absorpsiyon spektroskopisi ile analiz edilmiştir. Çalışılan mantar numunelerindeki eser metal içerik aralıkları demir için 4.6–3478.7 mg kg-1, krom için 5.1–19.9 mg kg-1, çinko için 10.4– 138.6 mg kg-1, kuşun için 5.8–28.0 mg kg-1 ve selenyum için 0.65–1.47 mg kg-1 olarak tespit edilmiştir. Bağıl standart sapma %10’nun altında bulunmuştur. Yöntemin doğruluğu sertifikalı referans malzemeler (BCR 191 Brown bread, ERM-BD 151 Skimmed milk powder) ile kontrol edilmiştir.Mushrooms are a popular food because they are an important source of essential amino acids, proteins and dietary fibers, but they have a great capacity to accumulate metals from substrate. Due to this reason, the content of 5 trace metals (Fe, Cr, Zn, Pb, Se) of fruit bodies of 21 fungi species originally found in Azdavay, Kastamonu Region, Turkey were analyzed by atomic absorption spectroscopy. The contents of investigated trace metals in mushroom samples were found to be in the range of 4.6–3478.7 mg kg-1 for Fe, 5.1–19.9 mg kg-1 for Cr, 10.4–138.6 mg kg-1 for Zn, 5.8–28.0 mg kg-1 for Pb and 0.65–1.47 mg kg-1 for Se. The relative standard deviations (R.S.D.) were found below 10%. The accuracy of procedure was confirmed by CRMs (BCR 191 Brown bread, ERM-BD 151 Skimmed milk powder)
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