Publications by authors named "Mohammad Saber Tehrani"

26 Publications

  • Page 1 of 1

Glucose Oxidase/Nano-ZnO/Thin Film Deposit FTO as an Innovative Clinical Transducer: A Sensitive Glucose Biosensor.

Front Chem 2020 15;8:503. Epub 2020 Jul 15.

Thin Layer and Nanotechnology Laboratory, Institute of Chemical Technology, Iranian Research Organization for Science and Technology (IROST), Tehran, Iran.

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 - techniques. In addition, field emission scanning electron microscopy and electrochemical impedance spectroscopy were applied to assess the morphology of the modified electrode surface. The - 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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fchem.2020.00503DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7374262PMC
July 2020

Validation of an Analytical Method for Simultaneous Determination of 18 Persistent Organic Pollutants in Trout Using LLE Extraction and GC-MS/MS.

Iran J Pharm Res 2019 ;18(3):1224-1238

Food Safety Research Center (FSRC), Shahid Beheshti University of Medical Sciences, Tehran, Iran.

Persistent organic pollutants, (POPs), are vast distributed compounds in environment which are recognized as one of the global pollution problems. These groups of materials being dangerous due to their high stability are accumulated in animal tissues and occurring in the food chain. One of the major paths through which persistent organic combinations access to human body is consuming polluted foods, particularly, fishes. Among aquatic animals, trout as one of the mostly consumed fishes in Tehran's food basket was studied. In this study, two categories of persistent organic pollutants: Organochlorine pesticides (OCPs) including HCB, Dieldrin, Methoxychlor, α-, ϒ-Chlordane, α-, β-Endosulfan and o,p'-DDE, p,p'-DDE, o,p'-DDT, p,p'-DDT and the second group Polychlonitated biphenyls (PCBs) including seven PCB congeners which are called indicator PCBs (IUPAC nos.: 28,52,101,118,138,153 and 180) were determined in trout by GC-MS/MS in MRM monitoring mode and LLE extraction. The average recoveries of OCPs and PCBs at five concentration levels (1, 2, 5, 10 and 20 ng/g for PCBs and 5 times for OCPs) were in the range of 73-112%. The relative standard deviations of POPs in fish were in the range of 1.4-17.9% for all of the concentration levels. The limit of detections (LODs) and the limit of quantitations (LOQs) were between 0.6-8.3 and 2-25 µg/kg, respectively. The results indicated the presence of organochlorine pesticides in trout and the levels of p,p'-DDE and p,p'-DDT were within the range of < LOQ -12.83 and < LOQ -10.2 ng/g ww (wet weight), respectively. According to the results, OCPs residues were lower than maximum residue levels set by European Council Directives.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.22037/ijpr.2019.1100748DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6934947PMC
January 2019

Magnetic solid phase extraction based on poly(β-cyclodextrin-ester) functionalized silica-coated magnetic nanoparticles (NPs) for simultaneous extraction of the malachite green and crystal violet from aqueous samples.

Environ Monit Assess 2020 Apr 3;192(5):262. Epub 2020 Apr 3.

Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, Iran.

In this research, an efficient sorbent based on poly(β-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, r ≥ 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 and 0.1 μg L, respectively. Precision of the method expressed as the relative standard deviations (RSDs) at concentration level of 100 μg L 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%.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10661-020-8185-6DOI Listing
April 2020

Synthesis of N-doped TiO/SiO/FeO magnetic nanocomposites as a novel purple LED illumination-driven photocatalyst for photocatalytic and photoelectrocatalytic degradation of naproxen: optimization and different scavenger agents study.

J Environ Sci Health A Tox Hazard Subst Environ Eng 2019 8;54(12):1254-1267. Epub 2019 Oct 8.

Department of Chemistry, Science and Research Branch, Islamic Azad University , Tehran , Iran.

N-doped TiO/SiO/FeO 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, 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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/10934529.2019.1673609DOI Listing
December 2019

Erratum to "Comparison between Different Extraction Methods for Determination of Primary Aromatic Amines in Food Simulant".

J Anal Methods Chem 2018 6;2018:6423428. Epub 2018 Sep 6.

Department of Analytical Chemistry, Faculty of Basic Science, Science and Research Branch, Islamic Azad University, Tehran, Iran.

[This corrects the article DOI: 10.1155/2018/1651629.].
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1155/2018/6423428DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6146773PMC
September 2018

Comparison between Different Extraction Methods for Determination of Primary Aromatic Amines in Food Simulant.

J Anal Methods Chem 2018 15;2018:1651629. Epub 2018 May 15.

Department of Analytical Chemistry, Faculty of Basic Science, Science and Research Branch, Islamic Azad University, Tehran, Iran.

The primary aromatic amines (PAAs) are food contaminants which may exist in packaged food. Polyurethane (PU) adhesives which are used in flexible packaging are the main source of PAAs. It is the unreacted diisocyanates which in fact migrate to foodstuff and then hydrolyze to PAAs. These PAAs include toluenediamines (TDAs) and methylenedianilines (MDAs), and the selected PAAs were 2,4-TDA, 2,6-TDA, 4,4'-MDA, 2,4'-MDA, and 2,2'-MDA. PAAs have genotoxic, carcinogenic, and allergenic effects. In this study, extraction methods were applied on a 3% acetic acid as food simulant which was spiked with the PAAs under study. Extraction methods were liquid-liquid extraction (LLE), dispersive liquid-liquid microextraction (DLLME), and solid-phase extraction (SPE) with C18 ec (octadecyl), HR-P (styrene/divinylbenzene), and SCX (strong cationic exchange) cartridges. Extracted samples were detected and analyzed by HPLC-UV. In comparison between methods, recovery rate of SCX cartridge showed the best adsorption, up to 91% for polar PAAs (TDAs and MDAs). The interested PAAs are polar and relatively soluble in water, so a cartridge with cationic exchange properties has the best absorption and consequently the best recoveries.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1155/2018/1651629DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5977034PMC
May 2018

A novel impedimetric glucose biosensor based on immobilized glucose oxidase on a CuO-Chitosan nanobiocomposite modified FTO electrode.

Int J Biol Macromol 2018 Oct 31;118(Pt A):649-660. Epub 2018 May 31.

Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, Iran.

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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ijbiomac.2018.05.228DOI Listing
October 2018

Facile preparation of multifunctional carbon nanotube/magnetite/polyaniline nanocomposite offering a strong option for efficient solid-phase microextraction coupled with GC-MS for the analysis of phenolic compounds.

J Sep Sci 2018 Jul 29;41(13):2736-2742. Epub 2018 May 29.

Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, Iran.

The aim of this study was to synthesize a highly efficient organic-inorganic nanocomposite. In this research, the carbon nanotube/magnetite/polyaniline nanocomposite was successfully prepared through a facile route. Monodisperse magnetite nanospheres were prepared through the coprecipitation route, and polyaniline nanolayer as a modified shell with a high surface area was synthesized by an in situ growth route and characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. The prepared nanocomposite was immobilized on a stainless-steel wire for the fabrication of the solid-phase microextraction fiber. The combination of headspace solid-phase microextraction using carbon nanotube/magnetite/polyaniline nanocomposite fiber with gas chromatography and mass spectrometry can achieve a low limit of detection and can be applied to determine phenolic compounds in water samples. The effects of the extraction and desorption parameters including extraction temperature and time, ionic strength, stirring rate, pH, and desorption temperature and time have been studied. Under the optimum conditions, the dynamic linear range was 0.01-500 ng/mL and the limits of detection of phenol, 4-chlorophenol, 2,6-dichlorophenol, and 2,4,6-trichlorophenol were the lowest (0.008 ng/mL) for three times. The coefficient of determination of all calibration curves was more than 0.990.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jssc.201800062DOI Listing
July 2018

Fe(3)O(4)/polyethylene glycol nanocomposite as a solid-phase microextraction fiber coating for the determination of some volatile organic compounds in water.

J Sep Sci 2017 02 30;40(3):717-724. Epub 2017 Jan 30.

Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, Iran.

A high-performance metal oxide polymer magnetite/polyethylene glycol nanocomposite was prepared and coated in situ on the surface of the optical fiber by sol-gel technology. The magnetite nanoparticles as nanofillers were synthesized by a coprecipitation method and bonded with polyethylene glycol as a polymer. The chemically bonded coating was evaluated for the headspace solid-phase microextraction of some environmentally important volatile organic compounds from aqueous samples in combination with gas chromatography and mass spectrometry. The prepared fiber was characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The mass ratio of nanofiller and polymer on the coating extraction efficiency, morphology, and stability were investigated. The parameters affecting the extraction efficiency, including the extraction time and temperature, the ionic strength, desorption temperature, and time were optimized. The sol-gelized fiber showed excellent chemical stability and longer lifespan. It also exhibited high extraction efficiency compared to the two types of commercial fibers. For volatile organic compounds analysis, the new fiber showed low detection limits (0.008-0.063 ng/L) and wide linearity (0.001-450 × 10 ng/L) under the optimized conditions. The repeatability (interday and intraday) and reproducibility were 4.13-10.08 and 5.98-11.61%, and 7.35-14.79%, respectively (n = 5). For real sample analysis, three types of water samples (ground, surface, and tap water) were studied.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jssc.201600888DOI Listing
February 2017

Solid-phase nanoextraction of polychlorinated biphenyls in water and their determination by gas chromatography with electron capture detector.

J Sep Sci 2017 01 13;40(2):449-457. Epub 2016 Dec 13.

Veterinary Organization, Tehran, Iran.

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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jssc.201600720DOI Listing
January 2017

Determination of residual nonsteroidal anti-inflammatory drugs in aqueous sample using magnetic nanoparticles modified with cetyltrimethylammonium bromide by high performance liquid chromatography.

ScientificWorldJournal 2014 1;2014:127835. Epub 2014 Jun 1.

Department of Chemistry, Science and Research Branch, Islamic Azad University, Poonak Hesarak, Tehran, Iran.

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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1155/2014/127835DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4058801PMC
April 2015

Polyvinylimidazole/sol-gel composite as a novel solid-phase microextraction coating for the determination of halogenated benzenes from aqueous solutions.

J Sep Sci 2014 Jun 15;37(12):1475-81. Epub 2014 May 15.

Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, Iran.

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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jssc.201301238DOI Listing
June 2014

Extraction and Determination of Cyproheptadine in Human Urine by DLLME-HPLC Method.

Iran J Pharm Res 2013 ;12(2):311-8

Department of Chemistry, Science and Research Branch, Islamic Azad University ,P.O.Box 14515- 775, Poonak Hesarak, Tehran, Iran.

Novel dispersive liquid-liquid microextraction (DLLME), coupled with high performance liquid chromatography with photodiode array detection (HPLC-DAD) has been applied for the extraction and determination of cyproheptadine (CPH), an antihistamine, in human urine samples. In this method, 0.6 mL of acetonitrile (disperser solvent) containing 30 μL of carbon tetrachloride (extraction solvent) was rapidly injected by a syringe into 5 mL urine sample. After centrifugation, the sedimented phase containing enriched analyte was dissolved in acetonitrile and an aliquot of this solution injected into the HPLC system for analysis. Development of DLLME procedure includes optimization of some important parameters such as kind and volume of extraction and disperser solvent, pH and salt addition. The proposed method has good linearity in the range of 0.02-4.5 μg mL(-1) and low detection limit (13.1 ng mL(-1)). The repeatability of the method, expressed as relative standard deviation was 4.9% (n = 3). This method has also been applied to the analysis of real urine samples with satisfactory relative recoveries in the range of 91.6-101.0%.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3813247PMC
November 2013

A single step technique for preparation of porous solid phase microextraction fibers by electrochemically co-deposited silica based sol-gel/Cu nanocomposite.

J Chromatogr A 2013 Feb 21;1278:1-7. Epub 2012 Nov 21.

Department of Chemistry, Science and Research Branch, Islamic Azad University, P.O. Box 14515-775, Tehran, Iran.

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).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.chroma.2012.11.035DOI Listing
February 2013

A novel strategy to increase performance of solid-phase microextraction fibers: electrodeposition of sol-gel films on highly porous substrate.

J Sep Sci 2012 Dec 29;35(23):3354-60. Epub 2012 Oct 29.

Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, Iran.

In the present work, the effect of substrate porosity for preparation of solid-phase microextraction (SPME) fibers was investigated. The fibers were prepared by electrodeposition of sol-gel coatings using negative potentials on porous Cu wire and compared with previous reported technique for preparation of SPME fibers using positive potentials on smooth gold wire. Porous substrate was prepared by electrodeposition of a thin layer of Cu on a Cu wire. The extraction capability of prepared fibers was evaluated through extraction of some aromatic hydrocarbons from the headspace of aqueous samples. The effect of substrate porosity and some operating parameters on extraction efficiency was optimized. The results showed that extraction efficiency of SPME fibers highly depends on porosity of the substrate. The LOD ranged from 0.005 to 0.010 ng/mL and repeatability at the 1 ng/mL was below 12%. Electrodeposited films were characterized for their surface morphology and thermal stability using SEM and thermogravimetric analysis, respectively. SEM analysis revealed formation of porous substrate and subsequently porous coating on the wire surface and thermogravimetric analysis showed high thermal stability of the prepared fiber.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jssc.201200580DOI Listing
December 2012

Simultaneous trace-levels determination of Hg(II) and Pb(II) ions in various samples using a modified carbon paste electrode based on multi-walled carbon nanotubes and a new synthesized Schiff base.

Anal Chim Acta 2012 Oct 23;746:98-106. Epub 2012 Aug 23.

Faculty of Chemistry, Bu-Ali Sina University, Hamedan, Iran.

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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.aca.2012.08.024DOI Listing
October 2012

Preparation and characterization of magnetic nanocomposite of Schiff base/silica/magnetite as a preconcentration phase for the trace determination of heavy metal ions in water, food and biological samples using atomic absorption spectrometry.

Talanta 2012 Aug 24;97:87-95. Epub 2012 Apr 24.

Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, Iran.

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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.talanta.2012.03.066DOI Listing
August 2012

A rapid, simple, liquid chromatographic-electrospray ionization, ion trap mass spectrometry method for the determination of finasteride in human plasma and its application to pharmacokinetic study.

Iran J Pharm Res 2012 ;11(1):59-67

Kimia R&D Institute, Tehran, Iran.

A fast, accurate, sensitive, selective and reliable method using reversed-phase high performance liquid chromatography coupled to electrospray ionization ion trap mass spectrometry was developed and validated for the determination of finasteride in human plasma. After protein precipitation with perchloric acid, satisfactory separation was achieved on a Zorbax Eclipse(®) C8 analytical column using a mobile phase consisted of acetonitrile, 2 mM ammonium formate buffer (58:42, pH adjusted at 2.5 using formic acid); the flow rate was 0.25 mLmin(-1) and the column oven was set to 50°C. Tamoxifen citrate was used as internal standard. This method involved the use of [M +H](+) ions of finasteride and IS at m/z 373 and 372 respectively with the selected ion monitoring (SIM) mode. The calibration curve was linear over the range of 0.1-60 ng mL(-1). The limit of quantification for finasteride in plasma was 0.1 ng mL(-1). The intra-day and inter-day repeatability (precision) were 2.68-13.87% and 2.14-14.69% respectively. Intra-day and inter-day accuracy were 98-101.57% and 99.7-110%. The assay method has been successfully used to estimate the pharmacokinetics of finasteride after oral administration of a 5 mg tablet of finasteride in 12 healthy volunteers.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3876561PMC
October 2014

Electrocatalytic oxidation and differential pulse voltammetric determination of using a carbon nanotubes modified electrode.

Anal Methods 2011 Feb;3(2):306-313

Department of Chemistry, Science and Research Branch, Islamic Azad University, P.O. Box 14515-775, Tehran, Iran.

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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c0ay00451kDOI Listing
February 2011

Simultaneous removal of heavy-metal ions in wastewater samples using nano-alumina modified with 2,4-dinitrophenylhydrazine.

J Hazard Mater 2010 Sep 25;181(1-3):836-44. Epub 2010 May 25.

Faculty of Chemistry, Bu-Ali Sina University, Hamadan, Iran.

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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jhazmat.2010.05.089DOI Listing
September 2010

Pre-concentration of phenolic compounds in water samples by novel liquid-liquid microextraction and determination by gas chromatography-mass spectrometry.

J Chromatogr A 2009 Dec 14;1216(49):8569-74. Epub 2009 Oct 14.

Department of Chemistry, Faculty of Science, Science and Research Branch, Islamic Azad University, PO Box 14515-775, Poonak-Hesarak, Tehran, Iran.

Pre-concentration and determination of 8 phenolic compounds in water samples has been achieved by in situ derivatization and using a new liquid-liquid microextraction coupled GC-MS system. Microextraction efficiency factors have been investigated and optimized: 9 microL 1-undecanol microdrop exposed for 15 min floated on surface of a 10 mL water sample at 55 degrees C, stirred at 1200 rpm, low pH level and saturated salt conditions. Chromatographic problems associated with free phenols have been overcome by simultaneous in situ derivatization utilizing 40 microL of acetic anhydride and 0.5% (w/v) K(2)CO(3). Under the selected conditions, pre-concentration factor of 235-1174, limit of detection of 0.005-0.68 microg/L (S/N=3) and linearity range of 0.02-300 microg/L have been obtained. A reasonable repeatability (RSD< or =10.4%, n=5) with satisfactory linearity (0.9995> or =r(2)> or =0.9975) of results illustrated a good performance of the present method. The relative recovery of different natural water samples was higher than 84%.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.chroma.2009.10.020DOI Listing
December 2009

Solid-phase extraction and spectrophotometric determination of mercury with 6-mercaptopurine in environmental samples.

Ann Chim 2007 Aug;97(8):675-83

Department of Chemistry, Science and Research Branch, Islamic Azad University, P. O. Box 14515-775, Tehran, Iran.

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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/adic.200790052DOI Listing
August 2007

Assessment of some elements in human permanent healthy teeth, their dependence on number of metallic amalgam fillings, and interelements relationships.

Biol Trace Elem Res 2007 May;116(2):155-69

Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, Iran.

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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/BF02685928DOI Listing
May 2007

Methylmercury determination in biological samples using electrothermal atomic absorption spectrometry after acid leaching extraction.

Anal Bioanal Chem 2006 Nov 1;386(5):1407-12. Epub 2006 Aug 1.

Department of Chemistry, Science and Research Branch, Islamic Azad University, P.O. Box 1415-775, Tehran, Iran.

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%.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00216-006-0668-yDOI Listing
November 2006

Chromium speciation by surfactant assisted solid-phase extraction and flame atomic absorption spectrometric detection.

Ann Chim 2004 May-Jun;94(5-6):429-35

Department of Chemistry, Islamic Azad University, Science & Research Campus, Tehran, Iran.

A new procedure has been developed for chromium speciation in aqueous solution by the use of micellar, ion-association, solid-phase extraction techniques (SPE) followed by flame atomic absorption spectrometry. The method was based on the use of C-18 bonded phase silica SPE disks for retention of ion-associated Cr(VI) with cetyl trimethyl ammonium bromide (CTAB), elution of the retained species and subsequent detection by flame atomic absorption spectrometry (FAAS). Cr(III) was oxidized by potassium persulfate to Cr(VI), then the total chromium was retained on the disk and determined by FAAS. The amount of Cr(III) was calculated by the difference between the total and Cr(VI) values. The calculated limit of detections (LOD) (based on 3sigma) are 15 microg L(-1) and 20 microg L(-1) for Cr(VI) and Cr(III) respectively. No considerable interferences have been observed from other investigated anions and cations and the method has been successfully applied to water samples taken from the Karoon River in Khuzestan province.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/adic.200490052DOI Listing
September 2004

A new second-derivative spectrophotometric method for the determination of permethrin in shampoo.

J Pharm Biomed Anal 2002 Nov;30(4):1379-84

Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, Iran.

Permethrin, a highly effective insecticide agent, has been widely used for the pest control in agriculture and the treatment of lice in human. A fast and reliable method for the determination of permethrin was highly desirable to support formulation screening and quality control. A second-derivative UV spectroscopic method was developed for the determination of permethrin in the shampoo dosage form after extraction. The second-derivative spectrum recorded between 250 and 310 nm, and a zero-crossing technique for second-derivative measurement at 279 nm was selected. It is found that the selectivity and sensitivity of the method to be in desirable range. In comparison with the direct UV method, second-derivative UV spectroscopy eliminates the interference from UV absorbing excipients. This method is also fast and economical in comparison with the more time-consuming GC method regularly used for formulation screening and quality control and can be used routinely by any laboratory possessing a spectrophotometer with a derivative accessory. The linear concentration ranges were 0.25-1.5 ppm (D2=0.00042Conc.+0.0018, r=0.9972, n=10). Between day of CV%
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/s0731-7085(02)00435-1DOI Listing
November 2002
-->