Search for: spectrophotometric
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    Direct orthogonal signal correction-partial least squares for simultaneous spectrophotometric determination of sulfamethoxazole and trimethoprim in pharmaceutical formulation and synthetic samples

    , Article Journal of the Chilean Chemical Society ; Volume 54, Issue 3 , 2009 , Pages 309-313 ; 07179324 (ISSN) Goodarzi, M ; Shahbazikhah, P ; Sohrabi, M. R ; Fathabadi, M ; Nouri, S. H ; Sharif University of Technology
    This work describes a very simple, novel and selective spectrophotmetric method for simultaneous determination of sulfamethoxazole and trimethoprim in pharmaceutical preparation and synthetics samples using direct orthogonal signal correction-partial least squares (DOSC-PLS). The all factors affecting on the sensitivity were optimized and the linear dynamic range for determining of these drugs was found. The PLS modeling was used for the multivariate calibration of the spectrophotometric data and DOSC was used for preprocessing of data matrices and the prediction results of model. The experimental calibration matrix was designed by measuring the absorbance over the range 200-400 nm for 32... 

    Sensitive spectrophotometric detection of dopamine, levodopa and adrenaline using surface plasmon resonance band of silver nanoparticles

    , Article Journal of the Iranian Chemical Society ; Volume 7, Issue SUPPL. 1 , 2010 , Pages S83-S91 ; 1735207X (ISSN) Hormozi Nezhad, M. R ; Tashkhourian, J ; Khodaveisi, J ; Sharif University of Technology
    A simple and effective procedure is proposed for spectrophotometric determination of catecholamines; Dopamine (1), L-Dopa (2) and Adrenaline (3). It was found that the reduction of Ag+ to silver nanoparticles (Ag-NPs) by these catecholamines in the presence of polyvinylpyrrolidone (PVP) as a stabilizing agent produced very intense surface plasmon resonance peak of Ag-NPs. The plasmon absorbance of the Ag-NPs allows the quantitative spectrophotometric detection of the catecholamines. The calibration curves derived from the changes in absorbance at λ = 440 nm were linear with concentration of Dopamine, Levodopa and Adrenaline in the range of 3.2×10-6- 2.0x10-5 M, 1.6x10-7 - 1.0×10-5 M,... 

    Thermodynamic complexation of dopamine with magnesium (II) in media with different dielectric constants

    , Article Main Group Metal Chemistry ; Volume 31, Issue 1-2 , 2008 , Pages 81-91 ; 07921241 (ISSN) Bagheri, A ; Boghaei, D. M ; Monajjemi, M ; Sharif University of Technology
    Walter de Gruyter GmbH  2008
    The solution equilibria of magnesium (II) complex formed with bidentate ligand of dopamine in acidic media (pH=∼4-∼6) have been studied in cosolvent systems at 15, 25, 35 ± 0.1° C and 1=0.2 mol.dm-3 sodium chloride, using phosphate buffer, with spectrophotometric methods. Evidence for the 2:1 complex was not observed for magnesium. The stability constant of the complex was determined KMg(HL)+ = ∼9 and the resulting free-energy changes obtained. The protonation constant of dopamine was determined under the above conditions. The results are discussed in terms of the effect of solvent on protonation and complexation  

    Spectrophotometric Determination of Glutathione and Cysteine Based on Aggregation of Colloidal Gold Nanoparticles

    , M.Sc. Thesis Sharif University of Technology Seyyed Hosseini, Ensieh (Author) ; Hormozi Nezhad, Mohammad Reza (Supervisor)
    low-molecular-weigth aminothiols such as cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) play a critical role in many biochemical pathways . Their level in biological fluids such as human plasma and urine are important for clinical diagnostics of a variety of diseases.
    We report herein the development of a highly sensitive colorimetric method for detection of cysteine and glutathione using the citrate capped gold nanoparticles (Au-NPs). This thiol containing molecules exhibit intriguing reactivities with Au nanoparticles. The reactivity involves the displacement of the citrate shell by the thiolate shell which is followed by intermolecular electrostatic interactions or... 

    Spectrophotometric Determination of Ametryn Herbicide in Drainage Water Based on Aggregation of Gold Nanoparticles Capped with Citrate

    , M.Sc. Thesis Sharif University of Technology Rastgar, Mortaza (Author) ; Hormozi-Nezhad, Mohammad Reza (Supervisor) ; Torkian, A (Supervisor)
    Due to vast use of Ametryn herbicide in agricultural and even non-agricultural activities and the possibility of contamination of carp and natural water sources by this herbicide, determination of this herbicide in surface and ground water sources is very important. Therefor introducing simple and sensitive method for determination of Ametryn is critical.
    This study demonstrate a simple and sensitive colorimetric method for the detection and determination of Ametryn based on aggregation of citrate capped AuNPs. Studied method relies upon shape and distance dependent AuNPs surface plasmon resonance. By replacing the sulfide containing Ametryn herbicide with citrate molecules on AuNPs... 

    Spectrophotometric Study of Formation of Donor-Acceptor Adducts of Selenium Dioxide with Amines and Pyridine like Bases

    , M.Sc. Thesis Sharif University of Technology Saniepay, Mersedeh (Author) ; Mohammadi Boghaei, Davar (Supervisor)
    Donor-acceptor adducts of selenium dioxide were formed with tree aromatic amines, two aliphatic amines and tree pyridine like bases. Characterization of these adducts were done through UV-Vis Spectrophotometer and IR Spectrophotometer and NMR Spectroscopy. In addition, the stoichiometry of these adducts were identified by elemental analysis (CHN). To approve the existence of selenium, Atomic absorption instrument was used.The results obtained from the entioned methods show that the adduct formation between selenium dioxide with amines and pyridine like bases are in following order: p-phenylen diamine.SeO2>NH5.SeO2,en.SeO2,cyclohexylamine.SeO2,... 

    Comparative study of partial least squares and multivariate curve resolution for simultaneous spectrophotometric determination of pharmaceuticals in environmental samples

    , Article RSC Advances ; Volume 5, Issue 86 , Aug , 2015 , Pages 70017-70024 ; 20462069 (ISSN) Parastar, H ; Shaye, H ; Sharif University of Technology
    Royal Society of Chemistry  2015
    The potentials of partial least squares regression (PLSR) and multivariate curve resolution alternating least squares (MCR-ALS) are evaluated for the simultaneous determination of diclofenac (DCF), naproxen (NAP), mefenamic acid (MEF) and carbamazepine (CBZ) as target analytes and gemfibrozil (GEM) as an interference in synthetic and real environmental samples. The analysis of first-order UV-Vis spectra is performed using PLSR with different variable selection methods, which include variable importance in projection (VIP), recursive weighted partial least squares (rPLS), regression coefficient (RV) and uninformative variable elimination (UVE), and using MCR-ALS with correlation constraint... 

    The advantage of spectrophotometric measurement for size-selective complexing of Cu(II) with O2N2-azacrown ligands

    , Article Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy ; Volume 139 , March , 2015 , Pages 286-289 ; 13861425 (ISSN) Ghanbari, B ; Gholamnezhad, P ; Sharif University of Technology
    Elsevier  2015
    A comparative investigation of the interaction of Cu(II) with a series of 15- to 19-membered mixed-donor dibenzo-substituted macrocyclic ligands, each incorporating an O2N2-donor set, has been carried out using UV-Visible studies in methanol. Although a ring size effect has been reported for a related series of Ni(II) complexes, no such metal ion discrimination has been reported for Cu(II) in terms of its binding constants with 14- to 17-membered macrocycles. Employing Job's method of continuous variation established 1:1 stoichiometry for the interaction between Cu(II) and 1-5. From UV-Visible studies applying the Benesi-Hildebrand equation, the binding constants (K) of Cu(II) with 1-5 were... 

    Spectrophotometric determination of glutathione and cysteine based on aggregation of colloidal gold nanoparticles

    , Article Scientia Iranica ; Volume 19, Issue 3 , June , 2012 , Pages 958-963 ; 10263098 (ISSN) Hormozi Nezhad, M. R ; Seyedhosseini, E ; Robatjazi, H ; Sharif University of Technology
    We report herein the development of a highly sensitive colorimetric method for the determination of cysteine and glutathione, based on aggregation of the citrate capped gold nanoparticles (Au NPs). This was exploited from high affinity of low-molecular-weight aminothiols towards the Au NPs surface, which could induce displacement of the citrate shell by the thiolate shell of target molecules, resulting in aggregation of the NPs through intermolecular electrostatic interaction or hydrogen-bonding. As a result of aggregation, which can be affected by the ionic strength, pH and concentration of Au NPs, the plasmon band at around 521 nm decreases gradually, along with formation of a new red... 

    A sensitive colorimetric detection of ascorbic acid in pharmaceutical products based on formation of anisotropic silver nanoparticles

    , Article Scientia Iranica ; Volume 17, Issue 2 F , 2010 , Pages 148-153 ; 10263098 (ISSN) Hormozi Nezhad, M. R ; Karimi, M. A ; Shahheydari, F ; Sharif University of Technology
    A sensitive colorimetric method for the detection of ascorbic acid was proposed in this research based on the reduction of silver ions by ascorbic acid in the presence of citrate-stabilized silver seeds, additional trisodium citrate and a polymer such as polyvinylpyrrolidone. The color of the stable sol is controlled by varying the concentration of trisodium citrate (TSC), polyvinylpyrrolidone, silver nitrate and silver seeds. The reduction of Ag + to triangle silver nanoparticles (Ag-NPs) by ascorbic acid in the presence of trisodium citrate (TSC) and silver seeds produced two very intense surface plasmon resonance peaks of Ag-NPs. The plasmon absorbance of Ag-NPs allows the quantitative... 

    Investigating the shape evolution mechanism of CdSe quantum dots by chemometrics analysis of spectrophotometry data

    , Article Journal of Physical Chemistry C ; Volume 112, Issue 47 , 2008 , Pages 18321-18324 ; 19327447 (ISSN) Hemmateenejad, B ; Hormozi Nezhad, M. R ; Sharif University of Technology
    The study on the mechanism of the shape evolution of nanocrystaline particles is an important and emerging field, which is applicable in the shaped control synthesis of nanoparticles. As an alternative to transmittance electron microscopy (TEM), which is already used in the study of nanoparticles, in this article a simple spectrophotometric method has been proposed utilizing the advantages of chemometrics methods in analyzing overlapped and complex spectral data. The evolutionary visible absorbance data of CdSe quantum dots through particle formation were analyzed by factor analysis, evolving factor analysis, and multivariate curve resolution-alternative least-squares analysis, by which four...