Spectrofluorimetric Study of the Inclusion Complex of 7-Hydroxymethylnalidixic Acid with γ-Cyclodextrin in Aqueous Solution

1997 ◽  
Vol 51 (5) ◽  
pp. 684-688 ◽  
Author(s):  
Isabel Durán-Merás ◽  
Arsenio Muñoz De La Peña ◽  
Francisco Salinas ◽  
Isabel Rodríguez Cáceres
Keyword(s):  
Aqueous Solution ◽  
Inclusion Complex ◽  
Formation Constant ◽  
Spectral Characteristics ◽  
Stoichiometric Ratio ◽  
Acid Base ◽  
Method Of Determination ◽  
Cyclodextrin Cavity ◽  
Complexation Process

A fluorimetric study on the spectral characteristics and acid-base behavior of 7-hydroxymethylnalidixic acid has been performed. The host–guest complexation process between γ-cyclodextrin and 7-hydroxymethylnalid ixic acid has also been investigated by fluorescence spectroscopy. Scatchard and Benesi-Hildebr and methods have been applied to determine the stoichiometry of the complex, and a 1:1 stoichiometric ratio has been established. A K1 = 118 ± 25 M−1 formation constant has been calculated for the inclusion complex, by using the changes produced on the fluorescence of 7-hydroxymethylnalid ixic acid, when it is included on the hydrophobic cyclodextrin cavity. A fluorimetric method of determination of 7-hydroxymethylnalid ixic acid, in γ-cyclodextrin aqueous solution, has been proposed. The analytical parameters and detection and quantification limits of the method have been determined.

Spectral characteristics of desipramine in β-cyclodextrin cavity through inclusion complex

2016 ◽  
Vol 53 (12) ◽  
pp. 781-790 ◽  
Author(s):  
Muthusamy Viswalingam ◽  
Samikannu Prabu ◽  
Krishnamoorthy Sivakumar ◽  
Rajaram Rajamohan
Keyword(s):  
Inclusion Complex ◽  
Spectral Characteristics ◽  
Cyclodextrin Cavity

scholarly journals Determination of the level of freshness of snail meat according to the content of the enzyme reductase

2020 ◽  
pp. 123-129
Author(s):  
І. V. Yatsenko ◽  
◽  
I. V. Zabarna ◽  
N. M. Bogatko ◽  
K. A. Rodionova ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Methylene Blue ◽  
Bacterial Contamination ◽  
Blue Color ◽  
State Control ◽  
Meat Extract ◽  
Normative Documents ◽  
Method Of Determination ◽  
Consumer Services

To search and use of alternative sources of animal protein is an urgent problem in Ukraine. In this aspect, snail meat is interesting, due to its nutritional value. Meat contains protein, essential vitamins and amino acids for humans, and does not contain cholesterol and unhealthy fats. There is no a comprehensive system for monitoring the safety and quality of snail meat in the system of state control of Ukraine for compliance with food legislation. Consequently, the question of determination of its safety, including and the degree of freshness is an urgent task. The method of determination of the level of freshness of snail meat, according to the content of the enzyme reductase with 0,1 % aqueous solution of methylene blue, was developed. This authors` approach is proposed both a qualitative and quantitative method to determine the degree of freshness of snail meat, according to other methods its safety determination. It has an advantage against existing methods because the safety of snail meat could be determine in different technological processing at different storage times by qualitative indicators of bacterial contamination of meat, depending on the level of freshness. According to the results of this method, it is able to obtain quantitative indicators of bacterial contamination of freshness of snail meat with the aim to determine its level. It was carried out that in fresh snail meat there is a discoloration in the meat extract after thermostating during 2,5 hours or it does not discolor (there is a stable blue color) – up to 103 CFU/g. In snail meat of dubious freshness, the meat extract is discolored in period from 40 minutes up to 2,5 h (104-105 CFU/g); in stale snail meat, discoloration of the meat extract is achieved in 20–40 minutes (106 CFU/g and more). The developed method of determination the freshness of snail meat according to the content of the enzyme reductase with 0,1% aqueous solution of methylene blue can be used in production laboratories at producing capacity for production, processing, sale and storage of snail meat, as well as in state laboratories of the State Food and Consumer Services of Ukraine. In addition, obtained data could make the basis for the development of normative documents in the system of state control over the safety of snail meat in Ukraine.

scholarly journals SYNTHESIS, COORDINATION AND ACID-BASE PROPERTIES OF MESO-DINITROSUBSTITUTED DERIVATIVES OF 5,15-DIPHENYL-β-OCTAALKYLPORPHINE

2018 ◽  
Vol 61 (6) ◽  
pp. 17
Author(s):  
Svetlana G. Pukhovskaya ◽  
Yulia B. Ivanova ◽  
Dmitry A. Erzunov ◽  
Aleksander S. Semeykin ◽  
Sergei A. Syrbu
Keyword(s):  
Spectral Characteristics ◽  
Spectrophotometric Titration ◽  
Basicity Constant ◽  
Acidity Constant ◽  
Electronic Effects ◽  
Acid Base ◽  
Electronic Effects Of Substituents ◽  
Derivatives Of ◽  
Base Properties

Presented work shows results of synthesis and spectrophotometric researches on properties of meso-dinitrosubstituted derivatives of 5,15-diphenyl-β-octaalkylporphyrin nitroderivatives in comparison with 2,8,12,18,3,7,13,17-octaethylporphyrin and 2,3,7,8,12,13,17,18-octaethyl-5,15-dinitroporphyrin. The method of spectrophotometric titration with perchloric acid (for determining the basicity constant) and 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU) was used in order to study the acid-base properties of porphyrins, namely to determine the acidity constant. The spectral characteristics of the ionized forms of 5,15-dinitro-10,20-diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporfin-F (I) and 5,15-dinitro-10,20-bis(4-nitrophenyl)-2,8,12,18-tetramethyl-3,7,13,17-tetraethylporphyrin (II) and the corresponding total constants of the acidic (pKa (I) = 6.00 and pKa (II) = 5.27) and the basic (pKb (I) = 19.78 and pKb (II) = 19.83) ionization were provided. The reaction of complexation of porphyrins with zinc acetate was studied by spectrophotometric method in pure acetonitrile and in mixed AN + DBU solvent. The influence of the degree of deformation of the tetrapyrrole macroring, the electronic effects of substituents and the acidity of the medium on the coordination and acid-base properties of porphyrins was analyzed. It was shown that the reactions of formation of metalloporphyrins with anionic porphyrin forms proceed with much higher rates compared to molecular ones, that is accompanied with a decrease in the energy parameters of the reaction. This is evidently due to the absence of energy costs for the deformation and cleaving N-H bonds of the reaction center, as well as the stronger polarization of the molecule, and as a consequence, the higher degree of solvation of anionic forms of porphyrins in the transition state. Thus, the determination of the conditions for the existence of dianionic forms of porphyrins gives grounds for the development of new sensor systems for the recognition and determination of the concentration of metal cations in liquid media due to a sharp increase in the rate of formation of metalloporphyrins in the presence of an organic base.Forcitation:Pukhovskaya S.G., Ivanova Yu.B., Erzunov D.A., Semeykin A.S., Syrbu S.A. Synthesis, coordination and acid-base properties of meso-dinitrosubstituted derivatives of 5,15-diphenyl-β-octaalkylporphine. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 6. P. 17-28

scholarly journals The fluorescence of a mercury probe based on osthol

2021 ◽  
Vol 17 ◽  
pp. 22-27
Author(s):  
Guangyan Luo ◽  
Zhishu Zeng ◽  
Lin Zhang ◽  
Zhu Tao ◽  
Qianjun Zhang
Keyword(s):  
Mass Spectrometry ◽  
Aqueous Solution ◽  
Detection Limit ◽  
Stoichiometric Ratio ◽  
Mercury Ions ◽  
Recognition Mechanism ◽  
H Nmr ◽  
Specific Selectivity ◽  
Good Linear Correlation

The ability of osthol (OST) to recognize mercury ions in aqueous solution was studied using fluorescence, UV–vis spectrophotometry, mass spectrometry, and 1H NMR spectroscopy, and the recognition mechanism is discussed. The results showed that OST and Hg2+ can form a complex with a stoichiometric ratio of 1:1. The binding constant was 1.552 × 105 L∙mol−1, having a highly efficient and specific selectivity for Hg2+. The fluorescence intensity of OST showed a good linear correlation with the Hg2+ concentration (6.0 × 10−5 to 24.0 × 10−5 mol∙L−1, R 2 = 0.9954), and the detection limit of the probe was 5.04 × 10−8 mol∙L−1, which can be used for the determination of Hg2+ traces.

Determination of the acidity constant of isothiocyanic acid in aqueous solution

2000 ◽  
Vol 78 (12) ◽  
pp. 1627-1628 ◽  
Author(s):  
Y Chiang ◽  
A J Kresge
Keyword(s):  
Aqueous Solution ◽  
Acid Solution ◽  
Acidity Constant ◽  
Acidity Function ◽  
Acid Base ◽  
Perchloric Acid Solution ◽  
Thiocyanate Ion ◽  
Acid Base Titration ◽  
Aqueous Perchloric Acid

Changes in absorbance of the thiocyanate ion (SCN–) at λ = 220 nm, measured in concentrated aqueous perchloric acid solution, were analyzed using a titration curve expression containing the Xo excess acidity function; this provided the acidity constant Ka = 19.2 ± 1.1 M, pKa = –1.28 ± 0.03, for isothiocyanic acid (SCNH).Key words: isothiocyanic acid (acidity of), thiocyanate ion (basicity of), acid–base titration in concentrated aqueous acids, Xo excess acidity function, Cox–Yates method.

Determination of the formation constant for the inclusion complex between rutin and methyl-β-cyclodextrin

1995 ◽  
Vol 315 (3) ◽  
pp. 357-363 ◽  
Author(s):  
S. Letellier ◽  
B. Maupas ◽  
J.P. Gramond ◽  
F. Guyon ◽  
P. Gareil
Keyword(s):  
Inclusion Complex ◽  
Formation Constant
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