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161.
Ultrasound‐assisted supramolecular‐solvent‐based microextraction combined with high‐performance liquid chromatography for the analysis of chlorophenols in environmental water samples
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An efficient, inexpensive and environmentally benign ultrasound‐assisted supramolecular‐solvent‐based microextraction technique combined with high‐performance liquid chromatography was used for the determination of chlorophenols in environmental water samples. Different factors such as amount of decanoic acid, volume of tetrahydrofuran, pH of the sample, ultrasound time and ionic strength were investigated and optimized. The optimized extraction conditions were 60 mg decanoic acid, 1.5 mL tetrahydrofuran, 3 min ultrasound time, without salt addition. Under this condition, the extraction recoveries were 83.0–89.3 with preconcentration factors of 94–102. The calibration curves were linear from 5.0–400.0 ng/mL with square of the correlation coefficient higher than 0.9998 and the limits of detection were between 1.5–2.0 ng/mL. The values of intra‐ and inter‐day relative standard deviations were 3.2–6.0 and 7.3–8.0%, respectively. Analysis of different samples showed that the concentration of 2,5‐dichlorophenol in Babolrood river water was 80.6 ng/mL. 相似文献
162.
Central composite design with the help of multivariate curve resolution in loadability optimization of RP‐HPLC to scale‐up a binary mixture
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Mohammadreza Taheri Roudabeh Sadat Moazeni‐Pourasil Majid Sheikh‐Olia‐Lavasani Ahmad Karami Alireza Ghassempour 《Journal of separation science》2016,39(6):1031-1040
Chromatographic method development for preparative targets is a time‐consuming and subjective process. This can be particularly problematic because of the use of valuable samples for isolation and the large consumption of solvents in preparative scale. These processes could be improved by using statistical computations to save time, solvent and experimental efforts. Thus, contributed by ESI‐MS, after applying DryLab software to gain an overview of the most effective parameters in separation of synthesized celecoxib and its co‐eluted compounds, design of experiment software that relies on multivariate modeling as a chemometric approach was used to predict the optimized touching‐band overloading conditions by objective functions according to the relationship between selectivity and stationary phase properties. The loadability of the method was investigated on the analytical and semi‐preparative scales, and the performance of this chemometric approach was approved by peak shapes beside recovery and purity of products. 相似文献
163.
Somayeh Tajik Hadi Beitollahi Zahra Dourandish Peyman Mohammadzadeh Jahani Iran Sheikhshoaie Mohammad Bagher Askari Parisa Salarizadeh Fariba Garkani Nejad Dokyoon Kim Soo Young Kim Rajender S. Varma Mohammadreza Shokouhimehr 《Electroanalysis》2022,34(7):1065-1091
Non-precious transition metal oxide nanomaterials offer numerous opportunities for various cost-effective electrochemical applications. This review article features the design and advancement of such nanomaterials with unique features applied for the fabrication of electrochemical devices. Also, it discusses various new syntheses of transition metal oxide nanoparticles (TMO NPs) via multiple chemicophysical and biological procedures. Further, the novel appliances of the TMO NPs with varying sizes and morphologies are appraised. The advantages and challenges of a number of investigations on the TMO NPs towards electrochemical applications are addressed with their standpoint of cost-effectiveness, applicability, and the efficiency of the introduced nanostructures for the industrial applications. 相似文献
164.
Mehdi Ebadi Wan Jeffrey Basirun Yatimah Alias Mohammadreza Mahmoudian 《Chemistry Central journal》2010,4(1):14
Electrodeposition of Ni-Co-Fe-Zn alloys was done in a chloride ion solution with the presence and absence of a Permanent Parallel
Magnetic Field (PPMF). The PPMF was applied parallel to the cathode surface. The deposition profile was monitored chronoamperometrically.
It was found that the electrodeposition current was enhanced in the presence of PPMF (9 T) compared to without PPMF. The percentage
of current enhancement (Γ%) was increased in the presence of PPMF, with results of Γ% = 11.9%, 16.7% and 18.5% at -1.1, -1.2
and -1.3 V respectively for a 2400 sec duration. In chronoamperometry, the Composition Reference Line (CRL) for Ni was around
57%, although the nobler metals (i.e. Ni, Co) showed anomalous behaviour in the presence of Zn and Fe. The anomalous behaviour
of the Ni-Co-Fe-Zn electrodeposition was shown by the Energy Dispersive X-Ray (EDX) results. From Atomic Force Microscopy
(AFM) measurements, it was found that the surface roughness of the Ni-Co-Fe-Zn alloy films decreased in the presence of a
PPMF. 相似文献
165.
Kavosh Majlesi Mohammadreza Gholamhosseinzadeh Saghar Rezaienejad 《Journal of solution chemistry》2010,39(5):665-679
The main aim of this research is to study the complexation of molybdenum(VI) with methyliminodiacetic acid in NaClO4 aqueous solutions at pH = 6.00 and ionic strengths (0.1<I/mol⋅dm−3<1.0) at 25 °C by using potentiometric and UV spectrophotometric measurements in order to obtain thermodynamic stability constants
at I=0 mol⋅dm−3. A comparison with previous literature data was made for the stability constants, though few data were available. The stability
constants data have been analyzed and interpreted by using extended Debye-Hückel theory, specific ion interaction theory and
parabolic model. Finally it might be concluded that parabolic model applies better for this complexation reaction. 相似文献
166.
Keivan Majidzadeh-A Vahid Khalaj Davami Fatemeh Hemayatkar Mahdi Barkhordari Farzaneh Adeli Ahmad Fereidoun Mahboudi 《Applied biochemistry and biotechnology》2010,162(7):2037-2048
Human tissue plasminogen activator (t-PA) plays a pivotal role in the treatment of acute myocardial infarction, ischemic stroke,
and deep vein thrombosis. It has the benefit of generating no adverse effects such as fibrinogen depletion, systemic hemorrhage,
and immunologic reactions. Human t-PA is a serine-protease enzyme containing 527 amino acid residues in five structural domains.
The correct folding of t-PA requires the correct pairing of 17 disulfide bridges in the molecule. A gene encoding full-length
human t-PA was cloned into pPICZαA expression vector downstream of alcohol oxidase promoter and α-mating signal sequence from
Saccharomyces cerevisiae and flush with the kex2 cleavage site to express the protein with a native N terminus. The methylotrophic yeast, Pichia pastoris GS115 strain, was transformed with this cassette, and methanol utilizing (mut+) transformants were selected for production
and secretion of human t-PA into culture media. SDS–PAGE and Western blot analysis showed the expressed bands of t-PA protein.
Zymography test indicated suitable folding and proper function of the expressed recombinant human t-PA in conversion of plasminogen
to plasmin and gelatin lysis. Amidolytic activity test showed the amidolytic activity of 1,650 IU/ml. The results of this
study concluded that P. pastoris methylotrophic yeast can be a suitable alternative for mammalian and prokaryotic expression systems to produce t-PA. 相似文献
167.
Extending to systems of hyperbolic-parabolic conservation laws results of Howard and Zumbrun for strictly parabolic systems, we show for viscous shock profiles of arbitrary amplitude and type that necessary spectral (Evans function) conditions for linearized stability established by Mascia and Zumbrun are also sufficient for linearized and nonlinear phase-asymptotic stability, yielding detailed pointwise estimates and sharp rates of convergence in Lp, 1?p?∞. 相似文献
168.
Mohammadreza Ghandforoush-Sattari Siminozar Mashayekhi Mahboub Nemati Philipp A. Routledge 《Chromatographia》2009,69(11-12):1427-1430
Taurine is an amino acid which is not incorporated into proteins but found in the cytosol of many mammalian cells, in high concentrations (2–30 mM). Increase in plasma taurine concentration has already been reported after surgical trauma, X-radiation, muscle necrosis, carbon tetrachloride-induced liver damage, and paracetamol overdose. Plasma taurine concentration was measured using LC with fluorescence detection following derivatization by o-phtalaldehyde plus 3-mercapto-propionic acid and α-aminobutyric acid as internal standard. Under these conditions the retention time of taurine was 10 min. This method was sensitive enough, to quantify 150 pg mL?1 and detect 50 pg mL?1 of taurine ranging normally between 65 and 179 mmol L?1 (8–22 μg mL?1). The validated method allowed simple determination of human plasma taurine in pharmacokinetic and biomarker studies. 相似文献
169.
Mohammadreza Khanmohammadi Nahid Mashkuri Masumeh Rostami Amir Bagheri Garmarudi 《Journal of Analytical Chemistry》2012,67(4):330-334
Sodium perborate (SPB) and sodium percarbonate (SPC) are solid compounds which act as sources of H2O2 in solution for stain bleaching, being considered as oxidizing agents in washing powder. This research deals with the quantitative
determination of SPB and SPC by an analytical procedure based on attenuated total reflectance Fourier transform infrared spectrometry,
utilizing partial least squares for data processing in the 1600-800 cm−1 spectral region. The statistical parameters such as R
2, standard error of prediction and relative standard deviation have been evaluated, while number of factors, number of scans
and resolution were optimized. The standard deviation of method was 0.006 and 0.010 for SPC and SPB, respectively. 相似文献
170.
Essential oil (EO) compositions of flowers and fruits of Hypericum perforatum L. and Hypericum scabrum L. growing wild in Kashan, central Iran, were determined by simultaneous steam distillation-solvent extraction method and analysed using GC-MS technique. Analysis revealed 28 identified compounds for H. perforatum, with two main components being α-pinene (25.36%) and α-amorphene (12.12%). Thirty-five compounds were identified in H. scabrum L. representing 98.60% of the oil with α-pinene (70.21%) and p-mentha-1,5-dien-8-ol (2.89%) as main components. Some new compounds were found in significant quantities which were not found in other chemotypes. The antioxidant activities of the EOs evaluated for the first time in this study using β-carotene bleaching and DPPH assays seemed to be attributed directly to α-pinene contents in them. Antibacterial activities of both mentioned EOs were higher than that of their main constituent, α-pinene, against Staphylococcus aureus and Escherichia coli. 相似文献