Search for: mass-spectrometry
0.008 seconds
Total 191 records

    Determination of the pesticide naptalam and its degradation products by positive and negative ion mass spectrometry

    , Article Fresenius' Journal of Analytical Chemistry ; Volume 369, Issue 2 , 2001 , Pages 176-183 ; 09370633 (ISSN) Ghassempour, A ; Arshadi, M. R ; Asghari, F. S ; Sharif University of Technology
    N-1-naphthylphtalamic acid (naptalam) and its degradation products, 1-naphthylamine and N-(1-naphthyl) phthalimide were simultaneously determined in river water by two independent mass spectrometric (MS) methods. These were negative ion MS (NIMS) and programmable temperature vaporizer gas chromatography mass spectrometry (PTV-GC MS) with electron impact ionization (positive ions). Prior to the NIMS analysis, the samples were preconcentrated by solid phase extraction (SPE) of C18 membrane discs. The PTV-GC MS studies were performed without any preconcentration procedure. Selected ion monitoring (SIM) and internal standardization with naphthalene were applied in both methods. The limits of... 

    Chemometrics-assisted gas chromatographic-mass spectrometric analysis of volatile components of olive leaf oil

    , Article Journal of the Iranian Chemical Society ; Volume 10, Issue 1 , 2013 , Pages 169-179 ; 1735207X (ISSN) Konoz, E ; Abbasi, A ; Moazeni, R. S ; Parastar, H ; Jalali Heravi, M ; Sharif University of Technology
    Iranian olive leaf essential oil components were extracted by microwave-assisted hydrodistillation and analyzed using gas chromatography-mass spectrometry. Ninety-seven components were identified by direct similarity searches for olive leaf essential oil. Chemometrics was used to find more components with the help of multivariate curve resolution methods. Eigenvalues-based methods and Malinowski functions were used for chemical rank determination of GC-MS data. Multivariate curve resolution-alternative least squares as an iterative method was used for resolving the overlapped and embedded peaks. With the use of this method the number of 97 components was extended to 127 components. Major... 

    Chemically bonded carbon nanotubes on modified gold substrate as novel unbreakable solid phase microextraction fiber

    , Article Microchimica Acta ; Volume 174, Issue 3 , September , 2011 , Pages 295-301 ; 00263672 (ISSN) Bagheri, H ; Ayazi, Z ; Sistani, H ; Sharif University of Technology
    A new technique is introduced for preparation of an unbreakable fiber using gold wire as a substrate for solid phase microextraction (SPME). A gold wire is used as a solid support, onto which a first film is deposited that consists of a two-dimensional polymer obtained by hydrolysis of a self-assembled monolayer of 3-(trimethoxysilyl)-1-propanthiol. This first film is covered with a layer of 3-(triethoxysilyl)-propylamine. Next, a stationary phase of oxidized multi-walled carbon nanotubes was chemically bound to the surface. The synthetic strategy was verified by Fourier transform infrared spectroscopy and scanning electron microscopy. Thermal stability of new fiber was examined by... 

    Electrospun composite of polypyrrole-polyamide as a micro-solid phase extraction sorbent

    , Article Analytical and Bioanalytical Chemistry ; 2011 , Pages 1-7 ; 16182642 (ISSN) Bagheri, H ; Aghakhani, A ; Akbari, M ; Ayazi, Z ; Sharif University of Technology
    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... 

    A sol-gel-based amino functionalized fiber for immersed solid-phase microextraction of organophosphorus pesticides from environmental samples

    , Article Microchemical Journal ; Volume 94, Issue 1 , 2010 , Pages 1-6 ; 0026265X (ISSN) Bagheri, H ; Ayazi, Z ; Babanezhad, E ; Sharif University of Technology
    A method based on immersed solid-phase microextraction (SPME) and gas chromatography mass spectrometry detection (GC-MS) for the determination of organophosphorous pesticides (OPPs) in aqueous samples was developed. A sol-gel based coating fiber was prepared using 3-(trimethoxysilylpropyl) amine as precursor. The synthesized fiber was prepared in a way to impart polar moiety into the coating network and would be more suitable for extracting polar and semi-polar organic pollutants. Important parameters influencing the extraction process were optimized and an extraction time of 40 min at 30 °C gave maximum peak area, when NaCl (20% w/v) was added to the aqueous sample. The linearity for... 

    Microextraction of antidepressant drugs into syringes packed with a nanocomposite consisting of polydopamine, silver nanoparticles and polypyrrole

    , Article Microchimica Acta ; Volume 183, Issue 1 , 2016 , Pages 195-202 ; 00263672 (ISSN) Bagheri, H ; Bani Hashemi, S ; Zandian, F. K ; Sharif University of Technology
    Springer-Verlag Wien 
    We describe a nanocomposite prepared from polydopamine, silver nanoparticles, and polypyrrole (PDA-Ag-PPy) that can be used for the microextraction in packed syringe (MEPS) of tricyclic antidepressants from urine samples. The PDA-Ag-PPy composite was prepared in-situ by the reduction of silver ion - doped PPy during oxidative polymerization of dopamine. The PDA-Ag coatings on the nanoribbon – shaped PPy represent a highly porous, inorganic–organic hybrid nanomaterial that has a wide range of applications. The nanocomposite was characterized by FTIR and scanning electron microscopy. It is shown to be an efficient sorbent for the MEPS of the tricyclic antidepressants amitriptyline, imipramine... 

    A magnetic multifunctional dendrimeric coating on a steel fiber for solid phase microextraction of chlorophenols

    , Article Microchimica Acta ; Volume 184, Issue 7 , 2017 , Pages 2201-2209 ; 00263672 (ISSN) Bagheri, H ; Manouchehri, M ; Allahdadlalouni, M ; Sharif University of Technology
    Springer-Verlag Wien  2017
    A polyamidoamine dendrimer was synthesized, placed on magnetite nanoparticles, and the resulting material was then employed as a fiber coating for use in solid phase microextraction of chlorophenols. The polyamidoamine was expected to be an efficient extracting medium due to the presence of multipolar groups and its inner porosity. A thin stainless steel wire was coated with the dendritic polyamidoamine polymer via electrolysis and chemical reactions. The coated fiber was investigated in terms of headspace solid phase microextraction of chlorophenols from aqueous samples followed by GC-MS quantitation. The calibration plots are linear in the 2–1000 ng⋅L−1 chlorophenol concentration ranges.... 

    Wireless electrochemical preparation of gradient nanoclusters consisting of copper(II), stearic acid and montmorillonite on a copper wire for headspace in-tube microextraction of chlorobenzenes

    , Article Microchimica Acta ; Volume 185, Issue 1 , 2018 ; 00263672 (ISSN) Enteshari Najafabadi, M ; Bagheri, H ; Sharif University of Technology
    Springer-Verlag Wien  2018
    This work introduces a new gradient fiber coating for microextraction of chlorobenzenes. Nanoclusters of organoclay-Cu(II) on a copper wire were fabricated by wireless electrofunctionalization. The resultant gradient coatings are more robust, and thermally and mechanically stable. Wireless electrofunctionalization was carried out in a bipolar cell under a constant deposition potential and using an ethanolic electrolyte solution containing stearic acid and montmorillonite. Stearic acid acts as an inexpensive and green coating while montmorillonite acts as a modifier to impart thermal stability. The gradient morphology of the nanoclusters was investigated by scanning electron microscopy,... 

    Big (Bio)chemical data mining using chemometric methods: a need for chemists

    , Article Angewandte Chemie (International ed. in English) ; Volume 61, Issue 44 , 2022 , Pages e201801134- ; 15213773 (ISSN) Parastar, H ; Tauler, R ; Sharif University of Technology
    NLM (Medline)  2022
    This Review summarizes how big (bio)chemical data (BBCD) can be analyzed with multivariate chemometric methods and highlights some of the important challenges faced by modern analytical researches. Here, the potential of chemometric methods to solve BBCD problems that are being encountered in chromatographic, spectroscopic and hyperspectral imaging measurements will be discussed, with an emphasis on their applications to omics sciences. In addition, insights and perspectives on how to address the analysis of BBCD are provided along with a discussion of the procedures necessary to obtain more reliable qualitative and quantitative results. In this Review, the importance of "big data" and of... 

    Novel unbreakable solid-phase microextraction fibers on stainless steel wire and application for the determination of oxadiargyl in environmental and agricultural samples in combination with gas chromatography-mass spectrometry

    , Article Talanta ; Vol. 128, issue , 2014 , Pages 231-236 ; ISSN: 00399140 Es-Haghi, A ; Baghernejad, M ; Bagheri, H ; Sharif University of Technology
    Sol-gel based solid-phase microextraction fibers supported by a stainless steel wire were fabricated and employed for GC-MS determination of oxadiargyl in real samples. The fibers were based on four compounds with different polarity: polar and non-polar (end-capped) poly(dimethylsiloxane) (PDMS), polyethylene glycol (PEG), and poly(ethylene-propyleneglycol)-monobutyl ether (UCON). For this purpose, the surface of the stainless steel was initially modified by (3-mercaptopropyl) trimethoxysilane. The results of the modification procedure were evaluated by cyclic voltammetry and energy dispersive X-ray (EDX) spectroscopy. After the modification, four different sol-gel based SPME fibers with... 

    Thorough analysis of Iranian spearmint essential oil: Combination of chemometrics and gas chromatography-mass spectrometry

    , Article Analytical Methods ; Vol. 6, Issue. 17 , 2014 , Pages 6753-6759 ; ISSN: 17599660 Jalali Heravi, M ; Moazeni-Pourasil, R. S ; Sereshti, H ; Sharif University of Technology
    The components of Iranian spearmint essential oil were identified and quantified using gas chromatography-mass spectrometry (GC-MS) combined with chemometric tools. A multivariate curve resolution (MCR) approach was used to overcome the problems of background, baseline offset and overlapping/embedded peaks in GC-MS. The peaks were resolved using heuristic evolving latent projection (HELP) and multivariate curve resolution-alternating least squares (MCR-ALS) techniques. A new pure variable selection method named multivariate curve resolution-objective function equal to zero (MCR-FEQZ) is introduced and was applied in this work. The performance of this technique was evaluated and confirmed... 

    New grafted nanosilica-based sorbent for needle trap extraction of polycyclic aromatic hydrocarbons from water samples followed by GC/MS

    , Article Chromatographia ; Volume 74, Issue 5-6 , September , 2011 , Pages 429-436 ; 00095893 (ISSN) Bagheri, H ; Roostaie, A ; Babanezhad, E ; Sharif University of Technology
    In this work, the preparation of a new grafted nanosilica-based sorbent was extensively investigated. An inexpensive modifier, cis-9-octadecenoic acid (oleic acid) was selected to be grafted on the surface of the nanosilica particles as the support. The grafting process was accurately confirmed by Fourier transform infra-red spectrometry (FT-IR). Applicability of the prepared sorbent was thoroughly examined by needle trap extraction (NTE) method. The grafted sorbent was dispersed in the appropriate solvent and carefully packed inside a steel needle. Feasibility of the method was completely examined using polycyclic aromatic hydrocarbons (PAHs), as model compounds. For extraction of analytes... 

    A combined micro-solid phase-single drop microextraction approach for trace enrichment of volatile organic compounds

    , Article Analytical Methods ; Volume 7, Issue 16 , Jun , 2015 , Pages 6514-6519 ; 17599660 (ISSN) Bagheri, H ; Zare, M ; Piri Moghadam, H ; Es haghi, A ; Sharif University of Technology
    Royal Society of Chemistry  2015
    An attempt was made to combine μ-solid phase extraction and headspace single drop microextraction techniques and use their advantages for trace determination of some volatile organic compounds in aqueous samples. After performing the two-step preconcentration approach, the desired analytes were determined by gas chromatography-mass spectrometry. A resorcinol-formaldehyde-based xerogel was used as the extraction medium in the μ-solid phase extraction (μ-SPE) method. Then, the extracted BTEX was eluted with a rather large amount of methanol. To remove the laborious process including solvent evaporation and further reconstitution, which is usually accompanied by loss of analytes and accuracy,... 

    Analysis of olive fruit essential oil: Application of gas chromatography-mass spectrometry combined with chemometrics

    , Article International Journal of Food Properties ; Volume 18, Issue 2 , Aug , 2015 , Pages 316-331 ; 10942912 (ISSN) Konoz, E ; Abbasi, A ; Parastar, H ; Moazeni, R. S ; Jalali Heravi, M ; Sharif University of Technology
    Taylor and Francis Inc  2015
    The extracted Iranian olive fruit essential oil was analyzed using gas chromatography-mass spectrometry. Multivariate curve resolution-alternative least squares approach was used to overcome the problem of background, baseline offset and overlapping/embedded peaks in gas chromatography-mass spectrometry. The analysis of gas chromatography-mass spectrometry data revealed that 90 components exist in the olive fruit essential oil. However, with the help of multivariate curve resolution-alternative least squares this number was extended to 141 components with concentrations higher than 0.01%. Major constituents in the olive fruit oil are 2-dodecenal (16.88%), 2-undecenal (10.71%), ethyl oleate... 

    Exploration of an easily synthesized fluorescent probe for detecting copper in aqueous samples

    , Article Dalton Transactions ; Volume 46, Issue 45 , 2017 , Pages 15827-15835 ; 14779226 (ISSN) Sanmartín Matalobos, J ; García Deibe, A. M ; Fondo, M ; Zarepour Jevinani, M ; Domínguez González, M. R ; Bermejo Barrera, P ; Sharif University of Technology
    Royal Society of Chemistry  2017
    An easily synthesized fluorescent probe for detecting copper in aqueous samples, with a short response time and at neutral pH, has been investigated. Through the chelation of Cu2+ ions or by binding to CuO nanoparticles, the fluorescence emission of the 2-(aminomethyl)aniline derivative H2L is quenched by over 50%. Spectroscopic determination of the association constants of H2L with some metal ions showed that the ligand has a higher affinity toward Cu2+ than toward other d-block metal ions. The comparative bonding ability of the aniline-based fluorescent probe in d-block metal complexes was studied in solution by a combination of UV-Vis, 1H NMR and mass spectrometry analyses. Besides these,... 

    Characterization of essential oil components of Iranian geranium oil using gas chromatography-mass spectrometry combined with chemometric resolution techniques

    , Article Journal of Chromatography A ; Volume 1114, Issue 1 , 2006 , Pages 154-163 ; 00219673 (ISSN) Jalali Heravi, M ; Zekavat, B ; Sereshti, H ; Sharif University of Technology
    The essential oil components of geranium oil cultivated in center of Iran were identified and determined using gas chromatography-mass spectrometry data combined with the chemometric resolution techniques. A total of 61 components accounting for 91.51% were identified using similarity searches between the mass spectra and MS database. This number was extended to 85 components using chemometric techniques. Various chemometric methods such as morphological scores, simplified Borgen method (SBM) and fixed size moving window evolving factor analysis (FSMWEFA) were used for determining the number of components, pure variables, zero concentration and selective regions. Then the overlapping peak... 

    Development and Application of Multivariate Curve Resolution Techniques for the Analysis of Complex Chromatographic Data

    , Ph.D. Dissertation Sharif University of Technology Parastar Shahri, Hadi (Author) ; Jalali Heravi, Mahdi (Supervisor)
    In recent years, chromatographic techniques as one of the most important analytical techniques have been greatly developed from instrumentation and data volume point of views. On the other side, multivariate curve resolution (MCR) techniques as a branch of chemometrics have potential for the analysis of multivariate and huge data sets. In addition, MCR methods have been developed very fast in these years and their potential have been shown in the analysis of different types of chemical data. Thus, combination of sophisticated chromatographic techniques (e.g. gas chromatography-mass spectrometry (GC-MS) or comprehensive two-dimensional gas chromatography (GC×GC)) with MCR techniques can be... 

    A superhydrophobic silica aerogel with high surface area for needle trap microextraction of chlorobenzenes

    , Article Microchimica Acta ; Volume 184, Issue 7 , 2017 , Pages 2151-2156 ; 00263672 (ISSN) Baktash, M. Y ; Bagheri, H ; Sharif University of Technology
    Springer-Verlag Wien  2017
    The authors have synthesized a superhydrophobic silica aerogel by using a sol-gel technique. The material is shown to be an efficient sorbent for needle trap microextraction of chlorobenzenes. Hydrophobicity affects the performance of the sorbent as shown by altering the ratio between tetraethylorthosilicate (TEOS) and methyltrimethoxysilane when synthesizing the sorbent. The observed contact angle (which is >150°) underpins the superhydrophobic properties of the aerogel. The microstructure of the sorbent was investigated by BET adsorption, revealing a surface area above 1000 m2 g−1. The sorbent was applied to needle trap extraction of chlorobenzenes from aqueous samples, and their... 

    Chemometrics-assisted isotope ratio fingerprinting based on gas chromatography/combustion/isotope ratio mass spectrometry for saffron authentication

    , Article Journal of Chromatography A ; Volume 1657 , 2021 ; 00219673 (ISSN) Ghiasi, S ; Parastar, H ; Sharif University of Technology
    Elsevier B.V  2021
    In the present contribution, the capability of isotopic ratio mass spectrometry (IRMS) for saffron authentication and detection of four common plant-derived adulterants (marigold flower, safflower, rubia, and saffron style) was investigated. For this purpose, 62 authentic saffron samples were analyzed by elemental analyzer-IRMS (EA-IRMS) and gas chromatography-combustion-IRMS (GC-C-IRMS). In this regard, EA-IRMS and GC-C-IRMS isotope fingerprints of carbon-13 and nitrogen-15 isotopes of saffron components were provided and then analyzed by chemometric methods. Principal component analysis (PCA) showed two different behaviors regarding two main regions. Then, a representative saffron sample... 

    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) Javanmardi, H ; Naderi, M ; Bagheri, H ; Sharif University of Technology
    Elsevier Inc  2021
    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®...