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1.
Anal Methods ; 16(2): 205-213, 2024 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-38099454

RESUMO

An efficient strategy utilizing µ-thin layer chromatography coupled with laser ablation inductively coupled plasma mass spectrometry (µ-TLC-LA-ICP-MS) based on an IIP (ion imprinted polymer) was developed for the speciation of inorganic arsenic [As(III) and As(V)]. The characterization of the fabricated IIP was performed applying Fourier-transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). To prepare the thin layer chromatography plate, CaSO4 (as a binder) was incorporated with the IIP. Then, the surface of the TLC plate was swept by LA, which volatilized the species of arsenic from the thin layer chromatography plate which thereafter were introduced into the ICP-MS system. Various effective parameters on isolation efficiency, such as the IIP/CaSO4 mass ratio, mobile phase composition, and pH, were examined. Under optimized conditions, the developed method demonstrated a detection limit of 0.3 µg L-1 with a wide linear dynamic range of 0.2-100 µg L-1, and a relative standard deviation of 3.8. The performance of the developed method was investigated for the isolation of As(III) and As(V) in wastewater (Mouteh, Aghdareh, and Zarmehr mines) and human blood plasma real samples.

2.
J Sep Sci ; 45(7): 1362-1373, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35138031

RESUMO

A sensitive method based on liquid chromatography combined with a diode array detector was developed and validated to simultaneously determine tamoxifen, and its active metabolites N-desmethyltamoxifen, 4-hydroxytamoxifen, and endoxifen in human plasma samples. The green and sustainable vortex-assisted dispersive liquid-phase microextraction technique based on the natural hydrophobic deep eutectic solvent was used for the extraction and preconcentration of the analytes. Chemometrics and multivariate analysis were used to optimize the independent variables including the type and volume of deep eutectic solvent, extraction time, and ionic strength. Under optimal conditions, calibration curves were linear in a suitable range with the lower limits of quantification (0.8-10.0 µg/L), which covered the relevant concentrations of the analytes in plasma samples for a clinical study. Intra- and interday precision evaluated at three concentrations for the analytes were lower than 8.2 and 12.1%, respectively. Accuracy was in the range of 94.9-104.7%. The applicability of the developed method on human plasma samples illustrated the range 45.1-72.8, 98.4-128.3, 0.9-1.2, and 2.7-6.1 µg/L for tamoxifen, N-desmethyltamoxifen, 4-hydroxytamoxifen, and endoxifen, respectively. The validated method can be effective for the pharmacokinetics, pharmacodynamics, and therapeutic drug monitoring studies of tamoxifen and its main metabolites in biological fluids.


Assuntos
Neoplasias da Mama , Sobreviventes de Câncer , Microextração em Fase Líquida , Neoplasias da Mama/tratamento farmacológico , Quimiometria , Cromatografia Líquida de Alta Pressão/métodos , Solventes Eutéticos Profundos , Feminino , Humanos , Limite de Detecção , Microextração em Fase Líquida/métodos , Solventes/química , Tamoxifeno
3.
Food Chem ; 378: 132109, 2022 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-35033707

RESUMO

Potassium bromate, also reported as a carcinogenic agent, commonly functions to improve flour in the baking industry to increase bread volume. In this study, a green and novel preconcentration and microextraction method, termed as vortex assisted liquid-liquid microextraction combined with UV-Vis spectrophotometry was developed and utilized for trace determination of Potassium Bromate in food samples. Furthermore, various chemometric methods have been used. Under optimum conditions, the linearity range was obtained in the range between 0.02 and 2 µg/mL. Using the proposed analytical approach, the detection limits and quantitation of KBrO3 were 0.02 and 0.07 µg/mL, respectively. A pre-concentration factor of 22.2 was reported. The precision of the method was evaluated in the terms of repeatability and reproducibility and expressed by the relative standard deviation; the levels of them were considerably higher than 5.07 and 4.8%. The proposed approach was applied to the determination of trace bromate in different flour products.


Assuntos
Bromatos , Microextração em Fase Líquida , Bromatos/análise , Farinha/análise , Reprodutibilidade dos Testes
4.
Artigo em Inglês | MEDLINE | ID: mdl-34666891

RESUMO

Gas flow-assisted dispersive liquid-phase microextraction based on deep eutectic solvent was used to determine parabens in personal care products such as mouthwash, lidocaine gel, aloe vera gel, and skin tonic. A homemade extraction device was innovated, in which by passing the stream of gas bubbles through the deep eutectic solvent a thin layer of the extraction phase is coated on the surface of the bubbles. The extraction is finally achieved when the bubbles are going up through the sample. The single-factor experiments and response surface methodology were applied to optimize the independent variables. The linear range of the method was 0.5 to 1000 µg L-1, the coefficient of determination for the goal analytes was higher than 0.9989, the instrumental limit of detections were in the range 0.2-0.3 µg L-1, and the instrumental limit of quantifications were in the range 0.5-1.1 µg L-1, the relative standard deviations were <5.2% for repeatability and <11.2% for intermediate precision, and the enrichment factors were 66 to 87 obtained under the optimized conditions. A spiking approach by means of standard material was used to estimate accuracy. The relative recoveries were in the range 95.8-105.2%. By using mentioned strategies, the organic waste and energy consumption reduced, toxic reagents replaced with safer ones, and operator safety enhanced. Accordingly, these benefits have been simultaneously attained and, the proposed method was one step closer to automation and sustainable analytical chemistry.


Assuntos
Cosméticos/química , Microextração em Fase Líquida/métodos , Parabenos/análise , Parabenos/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Química Verde , Limite de Detecção , Modelos Lineares , Parabenos/química , Reprodutibilidade dos Testes , Solventes/química
5.
Front Chem ; 8: 503, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32760694

RESUMO

In the present research, a new biocompatible electrode is proposed as a rapid and direct glucose biosensing technique that improves on the deficiencies of fast clinical devices in laboratory investigations. Nano-ZnO (nanostructured zinc oxide) was sputtered by reactive direct current magnetron sputtering system on a precovered fluorinated tin oxide (FTO) conductive layer. Spin-coated polyvinyl alcohol (PVA) at optimized instrumental deposition conditions was applied to prepare the effective medium for glucose oxidase enzyme (GOx) covalent immobilization through cyanuric chloride (GOx/nano-ZnO/PVA/FTO). The electrochemical behavior of glucose on the fabricated GOx/nano-ZnO/PVA/FTO biosensor was investigated by I-V techniques. In addition, field emission scanning electron microscopy and electrochemical impedance spectroscopy were applied to assess the morphology of the modified electrode surface. The I-V results indicated good sensitivity for glucose detection (0.041 mA per mM) within 0.2-20 mM and the limit of detection was 2.0 µM. We believe that such biodevices have good potential for tracing a number of biocompounds in biological fluids along with excellent accuracy, selectivity, and precise analysis. The fast response time of the fabricated GOx/nano-ZnO/PVA/FTO biosensor (less than 3 s) could allow most types of real-time analysis.

6.
Environ Monit Assess ; 192(5): 262, 2020 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-32246207

RESUMO

In this research, an efficient sorbent based on poly(ß-cyclodextrin-ester)-functionalized silica-coated magnetic nanoparticles (MNPs-CDP) was prepared and used for magnetic solid-phase extraction of the malachite green (MG) and crystal violet (CV) from water samples prior to their determination by high-performance liquid chromatography-ultra violet detection (HPLC-UV). The synthesized nanoparticles were characterized by the field emission-scanning electron microscopy (FE-SEM) and Fourier transform infrared spectroscopy (FT-IR). Of course, the factors, which could influence the extraction efficiency like pH, sorbent amount, salt content, extraction time, desorption time, eluent type, and volume and sample volume, were optimized by response surface methodology. Then, for both of MG and CV, good linearity (0.1-200 µg L-1, r2 ≥ 0.99) was achieved under the optimized conditions. The limits of detection (LODs) and the limits of quantification (LOQs), for both of MG and CV, were 0.03 µg L-1 and 0.1 µg L-1, respectively. Precision of the method expressed as the relative standard deviations (RSDs) at concentration level of 100 µg L-1 was 5.6 and 4.2 for MG and CV, respectively. Ultimately, usability of proposed method was investigated by analysis of CV and MG in tap water, fish pond water, and the lake water, and the satisfactory recoveries were obtained in the range of 92-100.5%.


Assuntos
Violeta Genciana/química , Nanopartículas de Magnetita , Corantes de Rosanilina/química , Extração em Fase Sólida/métodos , Poluentes Químicos da Água/química , Adsorção , Monitoramento Ambiental , Limite de Detecção , Fenômenos Magnéticos , Dióxido de Silício , Espectroscopia de Infravermelho com Transformada de Fourier , beta-Ciclodextrinas
7.
Artigo em Inglês | MEDLINE | ID: mdl-31594452

RESUMO

N-doped TiO2/SiO2/Fe3O4 as a new magnetic photocatalyst that is active in visible light has been prepared by simple sol-gel method. The prepared samples were characterized by XRD, FESEM, EDX, TEM, BET, BJH, VSM, XPS, FT-IR, and DRS-UV/Vis analysis. The photocatalytic effect of synthesized samples on naproxen degradation was studied. The operational parameters were optimized through central composite design to achieve maximum efficiency. The optimum values for maximum efficiency were obtained at pH of 4.29, catalyst mass of 0.06 g, naproxen concentration of 9.33 mg L-1, and irradiation time of 217.06 min. At these optimum conditions, the maximum photocatalytic degradation percentages of naproxen were found to be 96.32% at desirability function value of 1.0. Coupling the electrical current with the photocatalytic process proved that the electrical current was considerably efficient in decreasing the degradation time of removing the naproxen from aqueous solutions. The photocatalytic activity of the nanoparticles was also studied under sunlight. Considering the results provided by UV-Vis spectrophotometry and total organic carbon, it was found that the prepared samples are extraordinarily efficient to degrade naproxen under both purple LED and solar lights. Furthermore, the effect of different scavenger agents on naproxen degradation has been studied.


Assuntos
Nanopartículas de Magnetita/química , Naproxeno/química , Dióxido de Silício/química , Titânio/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Luz , Nanocompostos/química , Naproxeno/isolamento & purificação , Fotólise , Poluentes Químicos da Água/isolamento & purificação
9.
Int J Biol Macromol ; 118(Pt A): 649-660, 2018 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-29859844

RESUMO

This research aims at elaborating on the construction of a novel nanostructured copper oxide (Nano-CuO) sputtered thin film on the conductive fluorinated-tin oxide (FTO) layer that was exploited to immobilize glucose oxidase (GOx) enzyme via chitosan for developing impedimetric glucose biosensing. The distinct Nano-CuO thin film was fabricated by reactive DC magnetron sputtering system at the optimized instrumental deposition conditions. The FTO/Nano-CuO/Chitosan/GOx biosensor containing several layers afforded excellent microenvironment for rapid biocatalytic reaction to glucose. Field emission-scanning electron microscopy (FE-SEM), Ultraviolet-Visible spectroscopy (UV-Vis), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) were established the morphology of modified electrode's surface and electrochemical behavior of glucose on the fabricated biosensor. Characterization of the surface morphology and roughness of CuO thin film by FE-SEM exhibits cavities of the nanoporous film as an effective biosensing area for covalent enzyme immobilization. Invented FTO/Nano-CuO/Chitosan/GOx biosensor was employed for glucose determination using the impedimetric technique. The impedimetric outcomes display high sensitivity for glucose (0.261 kΩ per mM) detection within 0.2-15 mM and limit of detection as 27 µM. The declared biosensor has been applied as a careful, noncomplicated, and exact biosensor for recognition of glucose in the real samples analysis.


Assuntos
Técnicas Biossensoriais/métodos , Quitosana/química , Cobre/química , Glucose Oxidase/química , Glucose/análise , Halogenação , Compostos de Estanho/química , Técnicas Biossensoriais/instrumentação , Glicemia/análise , Eletroquímica , Eletrodos , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Glucose Oxidase/metabolismo , Humanos , Modelos Moleculares , Nanocompostos/química , Conformação Proteica
10.
J Sep Sci ; 40(2): 449-457, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27958677

RESUMO

A solid-phase nanoextraction method has been developed for the extraction and preconcentration of polychlorinated biphenyls using carboxyl multiwalled carbon nanotubes as a solid nano-sorbent. Parameters affecting extraction efficiency such as sorbent amount, desorption solvent type and volume, extraction time, pH, and salt content have been studied. Under optimized conditions, the correlation coefficient was up to 0.9989, the limits of detection was in the range of 1.4-3.5 ng/L, and limits of quantification was between 4.8 and 11.6 ng/L. The recoveries were in the range of 99-106% for different spiked analytes. The relative standard deviation for water samples spiked with two different spiking levels has been between 4 and 10%. The proposed sustainable method is rapid, easy to use, and small consumption of organic solvent for the detection and determination of trace levels of polychlorinated biphenyls in environmental waters.

11.
ScientificWorldJournal ; 2014: 127835, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24982923

RESUMO

A simple and sensitive solid-phase extraction method for separation and preconcentration of trace amount of four nonsteroidal anti-inflammatory drugs (naproxen, indomethacin, diclofenac, and ibuprofen) using Fe3O4 magnetic nanoparticles modified with cetyltrimethylammonium bromide has been developed. For this purpose, the surface of MNPs was modified with cetyltrimethylammonium bromide (CTAB) as a cationic surfactant. Effects of different parameters influencing the extraction efficiency of drugs including the pH, amount of salt, shaking time, eluent type, the volume of solvent, amount of adsorbent, sample volume, and the time of desorption were investigated and optimized. Methanol has been used as desorption solvent and the extracts were analysed on a reversed-phase octadecyl silica column using 0.02 M phosphate-buffer (pH = 6.02) acetonitrile (65 : 35 v/v) as the mobile phase and the effluents were measured at 202 nm with ultraviolet detector. The relative standard deviation (RSD%) of the method was investigated at three concentrations (25, 50, and 200 ng/mL) and was in the range of 3.98-9.83% (n = 6) for 50 ng/mL. The calibration curves obtained for studied drugs show reasonable linearity (R (2) > 0.99) and the limit of detection (LODs) ranged between 2 and 7 ng/mL. Finally, the proposed method has been effectively employed in extraction and determination of the drugs in biological and environmental samples.


Assuntos
Anti-Inflamatórios não Esteroides/análise , Anti-Inflamatórios não Esteroides/química , Compostos de Cetrimônio/química , Cromatografia Líquida de Alta Pressão/métodos , Nanopartículas de Magnetita/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química , Cetrimônio
12.
J Sep Sci ; 37(12): 1475-81, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24668737

RESUMO

A polyvinylimidazole/sol-gel composite is proposed as a novel solid-phase microextraction fiber to extract five halobenzenes from the headspace of aqueous solutions in combination with gas chromatography with mass spectrometry. The prepared fiber was characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The obtained results showed that porous polyvinylimidazole/sol-gel composite was chemically deposited on fused silica fiber. The effect of important extraction parameters including extraction temperature, extraction time, and salt content were investigated. The optimum conditions were as follows: extraction temperature 25°C, extraction time 20 min, and salt concentration 30 w/v%. Detection limits and relative standard deviations of the developed method for halogenated benzenes were below 0.1 pg/mL and 15%, respectively. Repeatability of the proposed method, explained by relative standard deviation, varied between 5.48 and 9.15% (n = 5). The limits of detection (S/N = 3) ranged between 0.01 and 0.10 ng/L using gas chromatography with mass spectrometry with selected ion monitoring mode. For real sample analysis, three types of water samples with different matrices (ground, surface, and tap water) were studied. The optimized procedure was applied to extraction and method validation of halogenated benzenes in spiked water samples.


Assuntos
Benzeno/isolamento & purificação , Hidrocarbonetos Halogenados/isolamento & purificação , Imidazóis/química , Polivinil/química , Microextração em Fase Sólida/métodos , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Benzeno/química , Cromatografia Gasosa-Espectrometria de Massas , Géis/química , Água Subterrânea/química , Hidrocarbonetos Halogenados/química , Microextração em Fase Sólida/instrumentação , Poluentes Químicos da Água/química
13.
J Chromatogr A ; 1278: 1-7, 2013 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-23336939

RESUMO

In this study, electrochemically co-deposited 3-trimethoxysilyl propyl methacrylate (3TMSPMA)/Cu nanocomposite is introduced as a novel and single-step technique for preparation of efficient and unbreakable solid phase microextraction (SPME) fibers; having strong interaction between the substrate and the coating. The applicability of prepared nanocomposite films was evaluated through extraction of some aromatic pollutants as model compounds from the headspace of aqueous samples in combination with gas chromatography-mass spectrometry (GC-MS). Different parameters affecting the structure and composition of the deposited films including applied potential, electrodeposition time, and precursor concentration; and the parameters affecting extraction efficiency such as extraction temperature, extraction time, and salt content were investigated. The results showed that morphology and grain size of the films are strongly affected by the ratio between the sol-gel precursor and Cu(2+) ions. Furthermore, potential of deposition influences the composition of films as it controls the kinetics of sol-gel/Cu co-deposition. Finally, characterization of the deposited films was accomplished by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA).


Assuntos
Cobre , Técnicas Eletroquímicas , Géis , Nanocompostos , Dióxido de Silício , Cromatografia Gasosa-Espectrometria de Massas , Microextração em Fase Sólida
14.
Anal Chim Acta ; 746: 98-106, 2012 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-22975186

RESUMO

A modified carbon paste electrode based on multi-walled carbon nanotubes (MWCNTs) and 3-(4-methoxybenzylideneamino)-2-thioxothiazolodin-4-one as a new synthesized Schiff base was constructed for the simultaneous determination of trace amounts of Hg(II) and Pb(II) by square wave anodic stripping voltammetry. The modified electrode showed an excellent selectivity and stability for Hg(II) and Pb(II) determinations and for accelerated electron transfer between the electrode and the analytes. The electrochemical properties and applications of the modified electrode were studied. Operational parameters such as pH, deposition potential and deposition time were optimized for the purpose of determination of traces of metal ions at pH 3.0. Under optimal conditions the limits of detection, based on three times the background noise, were 9.0×10(-4) and 6.0×10(-4) µmol L(-1) for Hg(II) and Pb(II) with a 90 s preconcentration, respectively. In addition, the modified electrode displayed a good reproducibility and selectivity, making it suitable for the simultaneous determination of Hg(II) and Pb(II) in real samples such as sea water, waste water, tobacco, marine and human teeth samples.


Assuntos
Técnicas Eletroquímicas , Chumbo/análise , Mercúrio/análise , Nanotubos de Carbono/química , Animais , Benzaldeídos/química , Carbono/química , Eletrodos , Humanos , Íons/análise , Íons/química , Chumbo/química , Mercúrio/química , Penaeidae/química , Reprodutibilidade dos Testes , Rodanina/análogos & derivados , Rodanina/química , Bases de Schiff/química , Água do Mar/química , Nicotiana/química , Dente/química , Atum , Águas Residuárias/química
15.
Talanta ; 97: 87-95, 2012 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-22841051

RESUMO

A versatile and robust solid phase with both magnetic property and a very high adsorption capacity is presented on the basis of modification of iron oxide-silica magnetic particles with a newly synthesized Schiff base (Fe(3)O(4)/SiO(2)/L). The structure of the resulting product was confirmed by Fourier transform infrared (FT-IR) spectra, X-ray diffraction (XRD) spectrometry and transmission electron microscopy (TEM). We developed an efficient and cost-effective method for the preconcentration of trace amounts of Pb(II), Cd(II) and Cu(II) in environmental and biological samples using this novel magnetic solid phase. Prepared magnetic solid phase is an ideal support because it has a large surface area, good selectivity and can be easily retrieved from large volumes of aqueous solutions. The possible parameters affecting the enrichment were optimized. Under the optimal conditions, the method detection limit was 0.14, 0.19 and 0.12 µg L(-1) for Pb(II), Cd(II) and Cu(II) ions, respectively. The established method has been successfully applied to analyze real samples, and satisfactory results were obtained. All these indicated that this magnetic phase had a great potential in environmental and biological fields.


Assuntos
Métodos Analíticos de Preparação de Amostras/métodos , Análise de Alimentos/métodos , Metais Pesados/análise , Metais Pesados/química , Nanocompostos/química , Espectrofotometria Atômica/métodos , Água/química , Adsorção , Animais , Humanos , Concentração de Íons de Hidrogênio , Nanopartículas de Magnetita/química , Metais Pesados/isolamento & purificação , Bases de Schiff/química , Dióxido de Silício/química , Sonicação , Fatores de Tempo , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação
16.
Anal Methods ; 3(2): 306-313, 2011 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32938029

RESUMO

The electrocatalytic oxidation of hydroxylamine was studied at the surface of a carbon paste electrode (CPE) spiked with multi-wall carbon nanotubes (MWCNT) and 4-hydroxy-2-(triphenylphosphonio)phenolate (HTP). The modified electrode (HTP-MWCNT-CPE) exhibits an excellent electrochemical catalytic activity toward hydroxylamine oxidation. The results show that there is a dramatic enhancement on the anodic peak current of hydroxylamine oxidation at the HTP-MWCNT-CPE in comparison the value obtained at HTP-CPE and MWCNT-CPE. The kinetic parameters of the electron transfer coefficient, α, the heterogeneous electron transfer rate constant, k', and the exchange current density, j0, for oxidation of hydroxylamine at the HTP-MWCNT-CPE were determined using cyclic voltammetry. Differential pulse voltammetry exhibits three dynamic linear ranges of 2.0-10.0 µM, 10.0-1000.0 µM and 1000.0-8000.0 µM, and a lower detection limit of 0.16 µM for hydroxylamine. Finally, the modified electrode activity was studied for hydroxylamine determination in two water samples and satisfactory results were obtained.

17.
J Hazard Mater ; 181(1-3): 836-44, 2010 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-20542378

RESUMO

2,4-Dinitrophenylhydrazine (DNPH) immobilized on sodium dodecyl sulfate coated nano-alumina was developed for the removal of metal cations Pb(II), Cd(II), Cr(III), Co(II), Ni(II) and Mn(II) from water samples. The research results displayed that adsorbent has the highest adsorption capacity for Pb(II), Cr(III) and Cd(II) in ions mixture system. Optimal experimental conditions including pH, adsorbent dosage and contact time have been established. Langmuir and Freundlich isotherm models were applied to analyze the experimental data. The best interpretation for the experimental data was given by the Freundlich adsorption isotherm equation for Mn(II), Pb(II), Cr(III) and Cd(II) ions and by Langmuir isotherm equation for Ni(II) and Co(II) ions. Desorption experiments by elution of the adsorbent with a mixture of nitric acid and methanol show that the modified alumina nanoparticles could be reused without significant losses of its initial properties even after three adsorption-desorption cycles. Thus, modified nano-alumina with DNPH is favorable and useful for the removal of these metal ions, and the high adsorption capacity makes it a good promising candidate material for Pb(II),Cr(III) and Cd(II) removal.


Assuntos
Óxido de Alumínio/química , Metais Pesados/isolamento & purificação , Fenil-Hidrazinas/química , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Cádmio , Cromo , Chumbo
18.
Ann Chim ; 97(8): 675-83, 2007 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-17899881

RESUMO

A highly selective, sensitive and rapid method for the determination of trace amounts of inorganic mercury based on the reaction of Hg (II) with 6-mercaptopurine and the solid phase extraction of the complex on C18 membrane disks was developed. The 6-mercaptopurine selectively reacts with Hg (II) to form a complex in the pH range of 5-8. This complex was preconcentrated by solid phase extraction with C18 disks. An enrichment factor of 100 was achieved. The molar absorptivity of the complex is 0.26 x 10(-6) L. mol(-1) cm(-1) measured at 315 nm. The Beer's law is obeyed in the concentration range of 0.002-0.048 microg mL(-1). The relative standard deviation for eleven-replicated measurement of 0.04 microg mL(-1) is 1.5 %. The detection limit is 0.001 microg mL(-1) in the water samples. The advantage of the method is that the determination of Hg (II) is free from interference of almost all the cations and anions found in environment and wastewater samples. The determination of Hg (II) in water samples of different origins and marine sediment were carried out by the present method and cold vapor atomic absorption spectrometry (CVAAS). Also the method's accuracy was investigated by using SRM 2709. The obtained results by the present procedure were in good agreement with those of the CVAAS and certified value, so that the applicability of the proposed method was confirmed for the real samples.


Assuntos
Poluentes Ambientais/análise , Mercaptopurina/química , Mercúrio/análise , Extração em Fase Sólida/métodos , Espectrofotometria/métodos , Poluentes Ambientais/química , Poluentes Ambientais/isolamento & purificação , Concentração de Íons de Hidrogênio , Mercúrio/química , Mercúrio/isolamento & purificação , Sensibilidade e Especificidade
19.
Biol Trace Elem Res ; 116(2): 155-69, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17646685

RESUMO

In this study, 60 human permanent healthy teeth (without filling) were collected postmortem and analyzed using flame atomic absorption spectrometry (FAAS), cold vapor atomic absorption spectrometry (CVAAS), hydride generation atomic absorption spectrometry (HGAAS), and electrothermal atomic absorption spectrometry (ETAAS) for the determination of Ca, Hg, Se, Cu, and Ag. The concentration of these elements was assessed in carious and noncarious teeth, different tooth groups, with age and with number of amalgam fillings. A negative correlation was found between Ca and the number of amalgam fillings, and significant negative correlations were found between Ca and three other metals (Hg, Ag, and Cu) that indicate the possibility of substitutions of Ca by three other metals. Significant positive correlations were found among the number of amalgam fillings and Hg, Ag, Cu and Se showed metal concentration in permanent healthy teeth were affected by the presence of the number of amalgam filling. In addition, significant positive correlations between Hg and Ag, Hg and Cu, and Ag and Cu proved the suspicion that the Hg content in permanent healthy teeth was mainly found because of the influence of amalgam filling, not from other sources. Moreover, the significant positive correlation between Hg-Se and Ag-Se showed the formation of mercuric selenide and silver selenide complexes as part of a natural mechanism of detoxification. Consequently, the permanent healthy teeth would be considered as a bioindicator for the accumulation of long-term exposure of Hg and Ag.


Assuntos
Amálgama Dentário/análise , Mercúrio/análise , Metais/química , Prata/análise , Adolescente , Adulto , Idoso , Amálgama Dentário/farmacologia , Dentição Permanente , Eletroquímica/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Espectrofotometria Atômica , Oligoelementos/análise
20.
Anal Bioanal Chem ; 386(5): 1407-12, 2006 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16896613

RESUMO

An efficient and sensitive method for the determination of methylmercury in biological samples was developed based on acid leaching extraction of methylmercury into toluene. Methylmercury in the organic phase was determined by electrothermal atomic absorption spectrometry (ETAAS). The methylmercury signal was enhanced and the reproducibility increased by formation of certain complexes and addition of Pd-DDC modifier. The complex of methylmercury with DDC produced the optimum analytical signal in terms of sensitivity and reproducibility compared to complexes with dithizone, cysteine, 1,10-phenanthroline, and diethyldithiocarbamate. Method performance was optimized by modifying parameters such as temperature of mineralization, atomization, and gas flow rate. The limit of detection for methylmercury determination was 0.015 mug g(-1) and the RSD of the whole procedure was 12% for human teeth samples (n=5) and 15.8% for hair samples (n=5). The method's accuracy was investigated by using NIES-13 and by spiking the samples with different amounts of methylmercury. The results were in good agreement with the certified values and the recoveries were 88-95%.


Assuntos
Compostos de Metilmercúrio/análise , Temperatura , Ácidos/química , Grafite/química , Cabelo/química , Humanos , Compostos Organometálicos/química , Paládio/química , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Espectrofotometria Atômica/métodos , Espectrofotometria Atômica/normas , Tolueno/química , Dente/química
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