Loading...
Search for:
micro-solid-phase-extraction
0.012 seconds
Total 32 records
Simultaneous determination of theophylline, theobromine and caffeine in different tea beverages by graphene-oxide based ultrasonic-assisted dispersive micro solid-phase extraction combined with HPLC-UV
, Article RSC Advances ; Vol. 4, issue. 87 , 2014 , p. 47114-47120 ; Khosraviani, M ; Samadi, S ; Amini-Fazl, M. S ; Sharif University of Technology
Abstract
A simple ultrasound-assisted dispersive micro-solid phase extraction method based on graphene-oxide (GO) nanosorbents (UAD-μ-SPE), followed by high performance liquid chromatography-ultraviolet detection (HPLC-UV) was developed for the simultaneous determination of theophylline, theobromine and caffeine in different infusion tea samples. GO was synthesized by Hummers method and characterized with field emission-scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy. The GO sorbent was dispersed in the sample solution with the assistance of ultrasound to enhance adsorption and desorption performance and rates. The main parameters...
Electrospun composite of polypyrrole-polyamide as a micro-solid phase extraction sorbent
, Article Analytical and Bioanalytical Chemistry ; 2011 , Pages 1-7 ; 16182642 (ISSN) ; Aghakhani, A ; Akbari, M ; Ayazi, Z ; Sharif University of Technology
Abstract
A micro-solid phase extraction technique was developed using a novel polypyrrole-polyamide nanofiber sheet, fabricated by electrospinning method. The applicability of the new nanofiber sheet was examined as an extracting medium to isolate malathion as a model pesticide from aqueous samples. Solvent desorption was subsequently performed in a microvial, and an aliquot of extractant was injected into gas chromatography-mass spectrometry. Various parameters affecting the electrospinning process including monomer concentration, polyamide content, applied voltage, and electrospinning time were examined. After fabricating the most suitable preparation conditions, influential parameters on the...
Modified Polystyrene Based Sorbents for Extraction of Trace Organic Pollutants with a Wide Range of Polarity
, Ph.D. Dissertation Sharif University of Technology ; Bagheri, Habib (Supervisor)
Abstract
The main focus of this thesis is based on surface modification of polystyrene in order to prepare extractive phases appropriate for extraction of analytes with a wide polarity range. This goal was achieved by increasing surface polarity. In fact, improved wettability and the possibility of interaction with polar analytes after addition of functional groups on polystyrene surface were the main reason for increased extraction capacity. In the first research, different functional groups including amine, nitro, carboxyl and acetyl were added on polystyrene particles by chemical bonding and to investigate their influence on extraction process, 22 analytes with a wide polarity range (LogP=-2 to...
An innovative chemometric approach for simultaneous determination of polycyclic aromatic hydrocarbons in oil-contaminated waters based on dispersive micro-solid phase extraction followed by gas chromatography
, Article Microchemical Journal ; Volume 159 , 2020 ; Jabbari, A ; Parastar, H ; Sharif University of Technology
Elsevier Inc
2020
Abstract
In the present study, an analytical strategy was developed using reduced graphene oxide (rGO) as an effective sorbent in dispersive micro-solid phase extraction (DMSPE) for simultaneous determination of seven polycyclic aromatic hydrocarbons (PAHs) combined with gas chromatography (GC-FID). rGO was synthesized using modified Hummer's method and characterized using scanning electron microscope (SEM), atomic force microscope (AFM) and Raman spectroscopy. A rotatable central composite design (CCD) combined with multiple linear regression (MLR) and analysis of variance (ANOVA) was used for designing, modelling and optimization of the extraction procedure. In this regard, principal component...
A stable nitrogen-rich zinc-based metal organic framework to investigate the structural similarity effect on the sorption efficiency of nitrogen-containing compounds
, Article Microchemical Journal ; Volume 170 , 2021 ; 0026265X (ISSN) ; Naderi, M ; Bagheri, H ; Sharif University of Technology
Elsevier Inc
2021
Abstract
A stable porous zinc-based metal organic framework (MOF) containing nitrogen-rich bis-tetrazolate ligand was synthesized to study the role of similar structures concerning both extractive phase and the desired solutes to achieve greater sorption efficiency. With implementing a dispersive micro-solid phase extraction (d-µ-SPE) methodology, the sorption capability and influencing structural parameters i.e., porosity, surface area and interactions types were investigated for the synthesized zinc-bis-tetrazolate (ZnBT) MOF and compared with some synthesized sorbents such as MIL-101, MIL-101-NH2, cadmium naphthalene dicarboxylic acid dimethyl formamide [Cd(NDC)(DMF)], polyaniline and LiChrolut®...
Electrospinning of Core-shell Nanofibers for Extraction and Determination of Pesticide Residues from Aquatic Media
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Habib (Supervisor)
Abstract
Porosity and high surface area is a profound concept for creating advance materials. Nanofibers are an important class of nano materials which would be used as novel sorbents because of their high surface to volume ratio as a result of long lengths and nano-to-micro-scale diameters. Electrospining is a simple method for producing fine nanofibers from different meterials such as, polymers, composites and ceramics to prepare highly efficient sorbents. Moreover, electrospining has been developed for fabricating nanofibers with core-shell structures. These structures in compared with conventional fibers have gained higher attentions due to their high aspect ratios and flexiblity in surface...
Polybutylene Terephethalate-based Magnetic Nanofibers for Micro-solid phase Extraction of Triazines from Aquatic Media
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Habib (Supervisor)
Abstract
Porosity and high surface area is a profound concept for creating advance materials. Nanofibers are an important class of nanomaterials with high surface to volume ratio as a result of long lengths and nano-to-micro-scale diameters. Electrospinning is a simple method for producing nanofibers from different polymers and composites and prepare highly efficient sorbents. Polymeric nanocomposites are claimed to exhibit markedly improved mechanical, magnetic, thermal and electrical properties. Magnetic iron oxide nanoparticles have gained great attentions due to their low toxicity, stability and biocompatibility and have been extensively used to induce magnetic property to the desired sorbents....
Synthesis and Implementation of Metal-organic Frameworks Based on Chromium Metal Salt in μ-solid Phase Extraction of Anti-hypertension Drugs in Biological Samples
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Habib (Supervisor)
Abstract
Several metal-organic frameworks based on chromium metal salt and terephthalic acid were synthesized by the solvo-thermal method and modified directly using amino acids or their imidazole derivatives. Suitable characteristics of the synthesized novel MOFs led to their use as novel extracting phases for sample preparation. The sorbent’s performance in extracting anti-hypertension drugs such as eprosartan, losartan and valsartan was tested using the magnetic solid phase extraction which is a form of μ-SPE, followed by HPLC analysis. Different parameters effecting the extraction and desorption procedures were optimized to achieve the highest performance of extraction and sensitivity. Said...
Resorcinol-formaldehyde xerogel as a micro-solid-phase extraction sorbent for the determination of herbicides in aquatic environmental samples
, Article Journal of Separation Science ; Volume 38, Issue 13 , 2015 , Pages 2305-2311 ; 16159306 (ISSN) ; Zare, M ; Piri Moghadam, H ; Bagheri, H ; Sharif University of Technology
Abstract
In this study, organic aerogels were synthesized by the sol-gel polycondensation of mixed cresol with formaldehyde in a slightly basic aqueous solution. Carbon aerogels and xerogels are generated by pyrolysis of organic aerogels. The novel sol-gel-based micro-solid-phase extraction sorbent, resorcinol-formaldehyde xerogel, was employed for preconcentration of some selected herbicides. Three herbicides of the aryloxyphenoxypropionate group, clodinafop-propargyl, haloxyfop-etotyl, and fenoxaprop-P-ethyl, were extracted from aqueous samples by micro-solid-phase extraction and subsequently determined by gas chromatography with mass spectrometry. The effect of different parameters influencing the...
Modified Lignin Natural Polymer and Graphene Oxide Aerogels and Valuation of their Performance in Sample Preparation
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Habib (Supervisor)
Abstract
A green aerogel was prepared by synthesizing amine-modified lignin from sugarcane bagasse and further modification by CS2 and subsequent freeze drying. This aerogel was implemented as an extractive phase in a home-made online micro solid phase extraction-high performance liquid chromatography (μSPE-HPLC) setup for analyzing cardiovascular drugs (valsartan and losartan) in urine samples. To study the effect of functionalization, bare or functionalized lignin powders were mixed with graphene oxide (GO) at different ratios while functionalized lignin showed the highest efficiency. The prepared aerogel was analyzed using CHNS elemental analysis, and FT-IR spectrometry. Effects of influencing...
Electrospun Nanofibers and Their Application for Microextraction of Environmental Samples
, Ph.D. Dissertation Sharif University of Technology ; Bagheri, Habib (Supervisor)
Abstract
Novel electrospun nanofibers and their applications as the microextractionsorbents are the centre of this research. Polymeric nanofibers with diameter in the scale of nano-to-micro were prepared by the electrospinning method and employed for microextraction purposes. Two major microextraction methods included solid phase microextraction (SPME) and micro-Solid phase extraction (µ-SPE). In the first work, a novel SPME fiber was fabricated by electrospinning method. A thin stainless steel wire was coated by the network of polymeric nanofibers. The polymeric nanofiber coating on the wire was mechanically stable due to the fine and continuous nanofibers formation around the wire with a three...
A chitosan-polypyrrole magnetic nanocomposite as μ-sorbent for isolation of naproxen
, Article Analytica Chimica Acta ; Vol. 816 , 2014 , Pages 1-7 ; ISSN: 00032670 ; Roostaie, A ; Baktash, M. Y ; Sharif University of Technology
Abstract
An extracting medium based on chitosan-polypyrrole (CS-PPy) magnetic nanocomposite was synthesized by chemical polymerization of pyrrole at the presence of chitosan magnetic nanoparticles (CS-MNPs) for micro-solid phase extraction. In this work, magnetic nanoparticles, the modified CS-MNPs and different types of CS-PPy magnetic nanocomposites were synthesized. Extraction efficiency of the CS-PPy magnetic nanocomposite was compared with the CS-MNPs and Fe3O4 nanoparticles for the determination of naproxen in aqueous samples, via quantification by spectrofluorimetry. The scanning electron microscopy images obtained from all the prepared nanocomposites revealed that the CS-PPy magnetic...
A polypyrrole-based sorptive microextraction coating for preconcentration of malathion from aquatic media
, Article Chromatographia ; Volume 74, Issue 9-10 , 2011 , Pages 731-735 ; 00095893 (ISSN) ; Aghakhani, A ; Ayazi, Z ; Khakinezhad, M ; Sharif University of Technology
Abstract
A new micro-solid phase extraction method was developed by combining solid-phase extraction and stir bar sorptive extraction to benefit from the advantages of both techniques. A polypyrrole coating was electrochemically synthesized on the surface of an already used graphite furnace, employed in electro-thermal atomic absorption spectroscopy. The cylindrical geometry of the graphite tube provided a rather huge surface area, suitable for sorptive extraction. The novel sorbent coating was examined as an extracting medium to isolate malathion. Effects of different parameters such as extraction time, salt concentration, sample volume, desorption solvent and time were investigated and optimized....
Electrospun titania sol-gel-based ceramic composite nanofibers for online micro- solid-phase extraction with high-performance liquid chromatography
, Article Journal of Separation Science ; Vol. 37, issue. 15 , August , 2014 , pp. 1982-1988 ; ISSN: 16159306 ; Piri-Moghadam, H ; Rastegar, S ; Taheri, N ; Sharif University of Technology
Abstract
Titanium(IV) tetraisopropoxide was employed as a metal oxide sol-gel precursor to prepare ceramic composite nanofibers by the electrospinning system. To facilitate this process and obtain the desired nanofibers with higher aspect ratios and surface area, poly(vinylpyrrolidone) was added to the sol of titania. Four ceramic nanofibers sheets based on titania were prepared while each sheet contained different transition metals such as Fe-Mn, Fe-Ni, Fe-Co, and Fe-Mn-Co-Ni. The scanning electron microscope images showed good homogeneity for all the prepared ceramic composites with a diameter range of 100-250 nm. The sorption efficiency was investigated by a micro-solid-phase extraction setup in...
Dispersive micro-solid phase extraction using magnetic nanoparticle modified multi-walled carbon nanotubes coupled with surfactant-enhanced spectrofluorimetry for sensitive determination of lomefloxacin and ofloxacin from biological samples
, Article Materials Science and Engineering C ; Volume 60 , 2016 , Pages 30-36 ; 09284931 (ISSN) ; Pourghazi, K ; Hajjaran, S ; Sharif University of Technology
Elsevier Ltd
Abstract
A dispersive micro-solid-phase extraction (D-μ-SPE) procedure coupled with surfactant-enhanced spectrofluorimetric detection was developed for determination of ofloxacin and lomefloxacin from biological and environmental samples. The D-μ-SPE procedure was performed using magnetic Fe3O4 nanoparticle grafted multi-walled carbon nanotube as an efficient adsorbent. The main factors affecting the signal enhancement (including surfactant concentration and pH) and extraction efficiency (including pH, extraction time, sample volume, amount of magnetic adsorbent, and desorption conditions) were investigated in detail. Under the optimized conditions, the calibration curves were linear (R2 0.9995) over...
Graphene oxide-starch-based micro-solid phase extraction of antibiotic residues from milk samples
, Article Journal of Chromatography A ; Volume 1591 , 2019 , Pages 7-14 ; 00219673 (ISSN) ; Behkami, S ; Raoofi, M ; Bagheri, H ; Sharif University of Technology
Elsevier B.V
2019
Abstract
In this study, a method was described for the extraction of three antibiotic residues from cow milk samples using a graphene oxide–starch–based nanocomposite. The prepared nanocomposites were employed as an extractive phase for micro-solid phase extraction of antibiotics from cow milk samples. The extracted antibiotics, i.e. amoxicillin, ampicillin and cloxacillin, were subsequently analyzed by high-performance liquid chromatography–ultraviolet detection (HPLC–UV). Important variables associated with the extraction and desorption efficiency were optimized. High extraction efficiencies for the selected antibiotics were conveniently achieved using the starch–based nanocomposite as the...
Magnetic Field Assistedand Flow Injection μ-Solid Pahse Extraction Techniques
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Habib (Supervisor)
Abstract
The main goal of this thesis was to develop μ-solid extraction techniques using electrspun nanofibers under the influence of magnetic field along with flow injection system. The thesis is divided into two sections:The first chapter deals with the use of magnetic field for improving μ-solid phase extraction efficiencies. After preparing the magnetic-based electrospun nanofibers (PBt/MNPs), sufficient numbers of disc from the prepared electrospun composite mat were cut and used as packing materials in a cartridge. The prepared system was coupled on-line to liquid chromatography for microextraction of selected drugs of furosemide, naproxene, diclofenac and clobetasol propionate. The homogeneity...
Synthesis and Application of Nanocomposites Containing Metallic Nanoparticles for Microextraction of Environmental and Biological Samples
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Habib (Supervisor)
Abstract
This thesis deals with the synthesis and characterization of some nanostructured conductive polymers and their applications toward microextraction of drugs, environmental pollutants and pesticides from aqueous and biological samples. In chapters 3–6, silver nanoparticles and their relevant nanocomposites were applied as the desired extracting media while in the last chapter, a polyaniline nanocomposite, containing titanium oxide nanoparticles, was synthesized and employed as an efficient medium for the extraction purposes. In the first work, a nanocomposite based on polyaniline-silver nanoparticles (PANI-Ag NPs) was synthesized and used as an extraction medium for microextraction in packed...
Polysaccharide-Based Nanocomposites as Green Sorbents in Microextraction Methodologies
, Ph.D. Dissertation Sharif University of Technology ; Bagheri, Habib (Supervisor)
Abstract
This thesis is focused on the preparation and use of polysaccharides as extractive phases in various extraction methods, such as the micro solid phase extraction (µ-SPE), needle trap microextraction (NTME) and thin film microextraction (TFME).In the first research, feasibility of the online µ-SPE method using cellulose acetate (CA) fibers was investigated. For this purpose, CA fibers were prepared by electrospinning technique and then placed into µ-SPE cartridge. With this method, it was possible to simultaneously extract the drug compounds in the urine and plasma samples. The enrichment factor and limits of detection (LODs) were obtained in the range of 194-210 and 1.0-2.4 μg L-1,...
Synthesis Of A Stable Triazole-Containing Structure And Compare Its Sorption Capability Versus other Extractive Phases for the Sorption of Triazole Fungicides in Environmental Samples
,
M.Sc. Thesis
Sharif University of Technology
;
Bagheri, Habib
(Supervisor)
Abstract
In this study, a 1,2,3-triazole-containing ligand and the subsequent zinc-based MOF were synthesized. Then, in order to investigate the role of structural similarity of analytes and sorbent on sorption efficiency, the sorption capability of triazole-containing MOF along with several other well-known sorbents toward selected triazole fungicides were tested using dispersive micro solid phase extraction (d-μSPE). In order to further investigate the role of structural similarity on the sorption efficiency, the performance of synthesized MOF in the extraction of other compounds such as triazine herbicides, organochlorine, and organophosphorous pesticides was also evaluated. As expected, the...