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Aziz-Zanjani M.O.,K. N. Toosi University of Technology | Mehdinia A.,Iranian National Institute for Oceanography
Microchimica Acta | Year: 2014

Introduced in the 1990s, solid-phase microextraction (SPME) has found numerous applications. This is due to the solventless nature of SPME and the large variety of sorbents and coatings available. Highly diverse procedures have been applied to coat supports such as fused silica fibers or metal wires with sorbents in order to enhance capability, selectivity and robustness of SPME. Lately, research also is directed towards more simple methods for deposition of different types of coatings. Several of these methods have resulted in better stability and higher effective surface areas of the coatings. This review (with 128 references) covers the state of the art in methods for coating materials for use in SPME. It is divided into the following sections: (a) Dip methods and physical agglutination methods, (b) sol-gel technology, (c) chemical grafting, (d) electrochemical methods for coating (such as electrodeposition, anodizing and electrophoretic deposition), (e) electrospinning, (f) liquidphase deposition, and (g) hydrothermal methods. A final section covers conclusions and future trends. [Figure not available: see fulltext.] © 2014 Springer-Verlag Wien.

Mehdinia A.,Iranian National Institute for Oceanography | Ziaei E.,K. N. Toosi University of Technology | Jabbari A.,K. N. Toosi University of Technology
Electrochimica Acta | Year: 2014

Nanocomposit of multi-walled carbon nanotubes and tin oxide (MWCNTs/SnO2) was used as an anode material in Microbial fuel cells (MFCs). The anode was constructed by coating of the nanocomposits on the glassy carbon electrode (GCE). The MWCNTs-SnO2/GCE showed the highest electrochemical performance as compared to MWCNT/GCE and bare GCE anodes. MWCNTs-SnO2/GCE, MWCNT/GCE and bare GCE anodes showed maximum power densities of 1421 mWm-2, 699 mW m-2 and 457 mW m -2, respectively. The electrodes were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The electrochemical properties of the MFC have been investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). High conductivity and large unique surface area extremely enhanced the charge transfer efficiency and the growth of bacterial biofilm on the electrode surface in MFC. Comparison of the power density of the proposed MFC with the other one in the literature showed that the MWCNTs/SnO2 nanocomposit was a desirable anode material for the MFCs. © 2014 Elsevier Ltd.

Mehdinia A.,Iranian National Institute for Oceanography | Roohi F.,K. N. Toosi University of Technology | Jabbari A.,K. N. Toosi University of Technology
Journal of Chromatography A | Year: 2011

A new Fe 3O 4/polyaniline nanoparticle (PANI) material has been successfully developed as magnetic solid-phase extraction sorbent in dispersion mode for the determination of methylmercury (MeHg) in aqueous samples, via quantification by gas chromatography/mass spectrometry (GC-MS). The resultant core-shell magnetic solid-phase extraction nanoparticle (MSPE-NP) sorbent was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS) and Fourier transform-infrared (FTIR) spectroscopy. Fe 3O 4/PANI composites showed fibrous structure with diameters between 50 and 100nm for fibers. The MSPE-NP process involved the dispersion of the Fe 3O 4/PANI nanoparticles in water samples with sonication, followed by magnetic aided retrieval of the sorbent and then, solvent (hexane) desorption of extracted MeHg for GC-MS analysis. The extraction, derivatization and adsorption conditions were optimized by selecting the appropriate extraction parameters including the amount of sorbent, extraction time, derivatizing reagent volume and extraction solvent. The calibration graph was linear in the concentration range of 0.5-300ngmL -1 (R 2>0.993) with detection limit of 0.1ngmL -1 (n=3), while the repeatability was 4.1% (n=5). Enrichment factor was obtained as 91. Seawater sample was analyzed as real sample and good recoveries (>98%) were obtained at different spiked values. © 2011 Elsevier B.V.

Mehdinia A.,Iranian National Institute for Oceanography | Aziz-Zanjani M.O.,K. N. Toosi University of Technology
TrAC - Trends in Analytical Chemistry | Year: 2013

Since the introduction of solid-phase microextraction (SPME) in the 1990s, different types of coating have shown their crucial role in extraction efficiency. In the past decade, unique properties of nanostructured materials (e.g., large surface area, and remarkable thermal, mechanical and chemical stability) led to their application as desirable coatings in SPME. The current review classifies nanomaterial-based SPME coatings as based on carbon, polymer, silica or metal nanoparticles. It also briefly discusses new developments and methods in preparing nanomaterial-based SPME coatings. © 2012 Elsevier Ltd.

Mehdinia A.,Iranian National Institute for Oceanography | Aziz-Zanjani M.O.,K. N. Toosi University of Technology | Ahmadifar M.,K. N. Toosi University of Technology | Jabbari A.,K. N. Toosi University of Technology
Biosensors and Bioelectronics | Year: 2013

Molecular imprinting is an attractive technique for preparing mimics of natural and biological receptors. Nevertheless, molecular imprinting for aqueous systems remains a challenge due to the hydrogen bonding between templates and functional monomers destroyed in the bulk water. The hydrogen bonding between templates and monomers are the most crucial factor governing recognition, particularly in non-covalent molecularly imprinted polymers. Using mesoporous materials for molecular imprinting is an effective approach to overcome this barrier and to remove the limitations of the traditional molecularly imprinted polymers which include incomplete template removal, small binding capacity, slow mass transfer, and irregular materials shape. Here, SBA-15 was used as a mesoporous silica material for synthesis of molecularly imprinted polypyrrole. The pyrrole monomers and template molecules were immobilized onto the SBA-15 hexagonal channels, and then polymerization occurred. The resulting nanocomposites were characterized by Fourier transform infrared (FT-IR) analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods. In batch rebinding tests, the imprinted nanocomposites reached saturated adsorption within 100min and exhibited significant specific recognition toward the ascorbic acid (AA) with high adsorption capacity (83.7mgg-1). To further illustrate the recognition property of the imprinted nanocomposites, binary competitive and non-competitive adsorption experiments were performed with ascorbic acid, dopamine, paracetamol and epinephrine. The imprinting factors for these compounds in non-competitive adsorption experiments were 3.2, 1.5, 1.4 and 1.3, respectively. The results showed that the imprinted nanocomposites exhibited significant adsorption selectivity for the ascorbic acid against the related compounds. © 2012 Elsevier B.V..

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