Gohar Deilamy-Rad; Parisa Hossein-Khezri,; Pegah Pykarimah; Leila Elyasi
Abstract
In this study, the acid dissociation constants (pKa) of three indicators, bromocresol green, phenolphthalein and methyl orange, were determined by scanning the solution of indicators and deposited pH paper in these solutions (in each step of color-changing solution) and then chemometrics method. These ...
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In this study, the acid dissociation constants (pKa) of three indicators, bromocresol green, phenolphthalein and methyl orange, were determined by scanning the solution of indicators and deposited pH paper in these solutions (in each step of color-changing solution) and then chemometrics method. These methods are simple, fast, and inexpensive. For this reason, first, the vessels containing the indicator solution and pH paper (in each step of color-changing solution) were scanned by the scanner, and then the images of sample solutions and pH papers were transferred to a computer using Microsoft Photo Editor (Microsoft XP). RGB values were measured, in each pixel, with the image processing tool box of MATLAB. In MATLAB (2013) software, a novel program was written based on RGB values, for calculating pKa indicators. The agreement between obtained pKa by this method and values reported in the literature demonstrates the utility of the method here used.
Hossein Tavallali; Gohar Deilamy-Rad; Mohammad Ali Karimi; Elaheh Sharifi; Zahra Tavallali; Arshida Najafi-Nejad
Abstract
Bromopyrogallol Red (BPR) dye (Dibromopyrogallolsulfonphthalein), was evaluated as a highly selective colorimetric chemosensor for tin and citrate ion. BPR displayed rapid response, high specificity, visual determination and good selectivity toward tin and citrate ion over other competing cations and ...
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Bromopyrogallol Red (BPR) dye (Dibromopyrogallolsulfonphthalein), was evaluated as a highly selective colorimetric chemosensor for tin and citrate ion. BPR displayed rapid response, high specificity, visual determination and good selectivity toward tin and citrate ion over other competing cations and anions in DMSO/H2O (1:1 v/v) media. The sensing mechanism was discussed by UV–Vis, titration, and a comparison study. Over a wide range from 0.4 µmol L-1 to 153.8 µmol L-1 and 0.02 µmol L-1 to 1.08 µmol L-1, a good linear relationship between the absorbance and the concentration of tin and citrate ion was found respectively and the detection limit was estimated to be as low as 0.06 and 0.003 µmol L-1 (S/N = 3) for tin and citrate ion. This proposed chemosensor has also been successfully applied for the determination of citrate in real samples which demonstrates its value of practical applications in food and biological systems.
Hossein Tavallali; Gohar Deilamy-Rad; Abolfath Parhami; Sajedeh Lohrasbi
Volume 3, Issue 2 , September 2016, , Pages 76-87
Abstract
A new diazo based, Congo-Red-Cu , was developed to act as an ‘Off–On’ reversible fluorescent probe for CN− detection. The changes in solvent composition has been shown greatly effective on selectivity of anion sensing through eliminate of sulfite interference. Increasing the amount ...
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A new diazo based, Congo-Red-Cu , was developed to act as an ‘Off–On’ reversible fluorescent probe for CN− detection. The changes in solvent composition has been shown greatly effective on selectivity of anion sensing through eliminate of sulfite interference. Increasing the amount of ethanol up to 5% (v/v) cause a dramatic development in selectivity of CN−via inhibitory effect on sulfite interferent. The chemosensing behavior of the CR-Cu has been demonstrated through fluorescence, absorption, visual color changes and FT-IR studies. This chemosensor (CR-Cu) has been shown a significant visible color change and displays a remarkable fluorescent switch on in the presence of CN− ions. The ‘in situ’ prepared CN− complexes of CR-Cu shows high “Turn-Off” selectivity toward CO32− over the other anions. The detection limits for CN− were 90 and 20 nM for colorimetric and fluorometric methods respectively, that is far lower than the WHO guideline of 1.9 µM. The complex of CN− with CR-Cu also displayed ability to detect up to 15 nM CO32− among other competing anions through a fast response time of less than 30 s which is much lower than most recently reported chemosensor probes. It has been possible to build an INHIBIT logic gate for two binary inputs viz., CN− and CO32− by monitoring the fluorescence emission band at 446 nm as output. The development of fluorometric an ‘‘Off–On’’ reversible switch for three chemical inputs Cu2+, CN− and CO32− ions and mimics a molecular level keypad lock.
Hossein Tavallali; Gohar Deilamy-Rad; Hoda Ansari
Volume 1, Issue 2 , September 2014, , Pages 87-96
Abstract
A novel magnetic mixed hemimicell solid phase extraction (MMHSPE) technique for speciation analysis of soluble, ferrous and ferric iron in legumes sample by flame atomic absorption spectrometry analysis (FAAS) was developed. MMHSPE system consisting of alumina-coated magnetite nanoparticles (Fe3O4/Al2O3NPs) ...
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A novel magnetic mixed hemimicell solid phase extraction (MMHSPE) technique for speciation analysis of soluble, ferrous and ferric iron in legumes sample by flame atomic absorption spectrometry analysis (FAAS) was developed. MMHSPE system consisting of alumina-coated magnetite nanoparticles (Fe3O4/Al2O3NPs) modified by sodium dodecylsulfate-1-(2-pyridylazo)-2-naphthol (SDS-PAN) have been successfully synthesized as an extracting agent. The procedure is based on complexation of Fe(II) with PAN that immobilized on the SDS-coated Fe3O4/Al2O3 NPs. Total iron is subjected to a similar extraction procedure after reduction. Then Fe(III) has been calculated by subtracting Fe(ΙI) from the total iron. The new and rapid method of analyses (MMHSPE technique) has been successfully applied for the determination of iron ions in certified reference materials (NCS DC 73349—bush, branches and leaves; and TM-23.2—fortified water) and legumes samples with high efficiency. Under the optimum conditions of parameters, the recoveries of Fe(ΙI) by analyzing the seven spiked some legumes samples were between 96.0% and 103.6% and detection limits of Fe(ΙI) were between 1.7 and 3.1 ng mg−1. The results have been also indicated that Fe3+ concentrations obtained are always higher than the Fe2+ contents in legumes sample and Soy bean snack and Peanut have the maximum content of Fe2+.
