Organic chemistry
Masoumeh Hasani; Tayebeh Sayarpour; Abbas Karami; Masoud Shariati-rad
Abstract
Kinetic spectrophotometric second order data based on the reaction of 1,2-naphthoquinone-4-sulphonate (NQS) coupled with multivariate curve resolution-alternating least squares (MCR-ALS) has been proposed for simultaneous determination of ethylamine, propylamine and butylamine. Using second-order advantage, ...
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Kinetic spectrophotometric second order data based on the reaction of 1,2-naphthoquinone-4-sulphonate (NQS) coupled with multivariate curve resolution-alternating least squares (MCR-ALS) has been proposed for simultaneous determination of ethylamine, propylamine and butylamine. Using second-order advantage, MCR-ALS methodology can solve problems of quantitation of analyte in the presence of unknown and uncalibrated interferences. Ethylamine, propylamine and butylamine react differentially with NQS at pH 9.5. Therefore, determination of these amines has been carried out due to the difference between their reaction rates. Quantitative determination of each amine in the mixture is performed using a synthetic solution as standard containing only the amine of interest. The MCR-ALS results are evaluated by the residuals and parameters such as lack of fit. The quantitative determination of these amines in different synthetic mixtures and some real samples such as river water, well water, tap water and soil has been performed and the results have been found to have good recoveries.
Physical chemistry
Nasrin Sohrabi; Maryam Dookheh
Volume 3, Issue 3, pp. 180-282,Serial No. 8 , July 2015, , Pages 254-265
Abstract
In this study at first , an azo dye, 2,7- naphthalenediol, 2-[(4-Bromophenyl)azo (BPAND) as a ligand has been synthesized by addition of p-Bromoaniline to the modified montomorillonite K10 clay. This ligand was characterized using 1H-NMR, UV-Vis and IR spectroscopies. Subsequently, its interaction with ...
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In this study at first , an azo dye, 2,7- naphthalenediol, 2-[(4-Bromophenyl)azo (BPAND) as a ligand has been synthesized by addition of p-Bromoaniline to the modified montomorillonite K10 clay. This ligand was characterized using 1H-NMR, UV-Vis and IR spectroscopies. Subsequently, its interaction with calf thymus deoxyribonucleicacid ,ct-DNA was investigated in 5 mM phosphate buffer solution, pH=7 using UV-Vis absorption, thermal denaturation and viscosity measurement. From spectrophotometric titration experiments, the binding constant of BPAND with ct-DNA was found to be (2.89±0.2)×107 M-1 at 25°C. In order to determine changes in thermodynamic properties such as binding constant, Gibbs free energy, binding enthalpy and binding entropy, this experiment was done at various temperatures. The enthalpy and entropy changes were -2.852±0.634 kJ/mol and -814.065 ±2.52 J/mol.K, respectively.Thermal denaturation experiments show the increasing of melting temperature of ct-DNA (about 0.06°C less than 0.6) due to binding of BPAND ligand. From these results the mechanism and the stoichiometry of binding were determined. The results revealed that this interaction is exothermic (negative enthalpy change) along with negative entropy change. Therefore, the driving force in these interactions is enthalpy and the process is enthalpy-driven and suggest that the main driving force for the ct-DNA-BPAND complex formation is being Van der Waals or hydrogen binding.
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