scholarly journals Structure of the solubility diagram in the Na2SO4-Na2CO3-NaHCO3-H2O system at 0, 25 and 50 °С

2018 ◽  
Vol 5 (2) ◽  
pp. 104-108
Author(s):  
L. Soliev ◽  
◽  
M. T. Jumaev ◽  
R. O. Turaev ◽  
H. R. Makhmadov ◽  
...  
Keyword(s):  
Solubility Diagram

Synthesis of nickel selenites, their solubility and bonding in them

1982 ◽  
Vol 47 (8) ◽  
pp. 2069-2076 ◽  
Author(s):  
Miroslav Ebert ◽  
Zdeněk Mička ◽  
Ilona Peková
Keyword(s):  
Magnetic Properties ◽  
Hydrogen Bonding ◽  
Solubility Diagram ◽  
Reflectance Spectroscopy ◽  
Chloride Anion ◽  
Fluoride Anion ◽  
Infrared Absorption Spectroscopy ◽  
Magnetic Parameters ◽  
Nickel Cation ◽  
Spectrochemical Series

The solubility diagram of the NiSeO3-SeO2-H2O system at 25 °C was studied, and on its basis, Ni(HSeO3)2.2 H2O was prepared. This selenite and NiSeO3.2 H2O were investigated by infrared absorption spectroscopy and by electronic reflectance spectroscopy and their magnetic properties were determined. Based on the infrared spectra, the force constants of the selenium-oxygen bonds were determined and the hydrogen bonding was characterized. The electronic reflectance spectra and the magnetic parameters indicate an octahedral arrangement of the coordination sphere of the nickel cation and characterize the selenite anion as a ligand that in the spectrochemical series assumes a position between the fluoride anion and water and in the nephelauxetic series, between ethylenediamine and the chloride anion.

scholarly journals Thermodynamic Investigations on the Inclusion Complexation of Piroxicam with Cyclodextrin Derivatives

2005 ◽  
Vol 73 (3) ◽  
pp. 147-161 ◽  
Author(s):  
Charumanee S. ◽  
Weiss-Greiler P. ◽  
Wolschann P. ◽  
Viernstein H. ◽  
Titwan A. ◽  
...  
Keyword(s):  
Ph Value ◽  
Equilibrium Constants ◽  
Inclusion Complexation ◽  
Solubility Diagram ◽  
Phase Solubility ◽  
Cyclodextrin Derivatives ◽  
Ph Values ◽  
Solubility Behavior ◽  
Solubility Method ◽  
Different Temperatures

Thermodynamic studies of piroxicam in aqueous solution complexed with β-cyclodextrin (β-CD), γ-cyclodextrin (γ-CD) and two β-cyclodextrin derivatives, hydroxypropyl-β-cyclodextrin (HP-P-CD) and methyl-β-cyclodextrin (Me-β-CD) were performed at different temperatures and pH values using the phase solubility method. The phase solubility diagrams of β-CD, γ-CD and HP-β-CD is of AL-type behavior, indicating the formation of 1:l complexes. The related stability constants range from β-CD > γ-CD > Me-β-CD > HP-β-CD, respectively. An Ap-type solubility diagram is observed for Me-β-CD, indicating the formation of 1:2 complexes at higher CD concentrations. From the temperature dependence of the equilibrium constants the reaction enthalpies and entropies have been determined. The contributions of the reaction entropies are small and no enthalpy-entropy-compensation is observed, except for γ-CD, where a very small negative reaction entropy could be estimated. Moreover, the influence of the pH value is rather high because the differently charged forms of piroxicam show different solubility behavior in water.

scholarly journals Soluble 1:1 complexes and insoluble 3:2 complexes – Understanding the phase-solubility diagram of hydrocortisone and γ-cyclodextrin

2017 ◽  
Vol 531 (2) ◽  
pp. 504-511 ◽  
Author(s):  
Christian Schönbeck ◽  
Tobias L. Madsen ◽  
Günther H. Peters ◽  
René Holm ◽  
Thorsteinn Loftsson
Keyword(s):  
Solubility Diagram ◽  
Phase Solubility ◽  
Phase Solubility Diagram

scholarly journals Short-Stability Study of Rifaximin-Based Samples

2020 ◽  
Vol 103 (3) ◽  
pp. 743-746
Author(s):  
Ana Carolina Kogawa ◽  
Leena Peltonen ◽  
Hérida Regina Nunes Salgado ◽  
Marlus Chorilli
Keyword(s):  
Reaction Order ◽  
Solubility Diagram ◽  
Stability Study ◽  
New Drugs ◽  
Phase Solubility ◽  
Microbiological Analysis ◽  
Wet Milling ◽  
Pharmaceutical Technology ◽  
Microbiological Methods ◽  
Temperature And Humidity

Abstract Background Rifaximin is an oral antimicrobial with a daily dose ranging from 600 to 800 mg. It is classified as Class IV in the Biopharmaceutic Classification System. Thus, rifaximin-based samples were developed by complexation to β-cyclodextrin using a phase solubility diagram, and malaxation and decreasing particle size using wet milling. Objective Concomitant to the pharmaceutical technology, a stability studywas undertaken with the objective of verifying the integrity of the drug. Methods The stability of the new samples were studied for 6 months, without interruption, under controlled conditions of temperature and humidity in a climatic chamber. They were analyzed simultaneously by HPLC and microbiological turbidimetry at zero, 3, and 6 months. Results Two of the samples follow second reaction order and one follows zero reaction order. Microbiological analysis proved to be important in assessing the potency of rifaximin in one of the samples, and its results were more consistent than the results by HPLC. Conclusions The rifaximin-based samples were stable under controlled temperature and humidity conditions and the physical-chemical and microbiological methods were able to evaluate their behavior during the 6-month study. Highlights It is worth considering the development of these products, since the design process of formulation and pharmaceutical technology is financially more attractive than the development of new drugs that require high levels of investment in research and development, innovation of public policies, and regulatory actions.

Solubility diagram of the Cu–Ni nanosystem

2006 ◽  
Vol 18 (8) ◽  
pp. 2537-2551 ◽  
Author(s):  
A Shirinyan ◽  
M Wautelet ◽  
Y Belogorodsky
Keyword(s):  
Solubility Diagram

scholarly journals Physical properties and biological activities of hesperetin and naringenin in complex with methylated β-cyclodextrin

2015 ◽  
Vol 11 ◽  
pp. 2763-2773 ◽  
Author(s):  
Waratchada Sangpheak ◽  
Jintawee Kicuntod ◽  
Roswitha Schuster ◽  
Thanyada Rungrotmongkol ◽  
Peter Wolschann ◽  
...  
Keyword(s):  
Physical Properties ◽  
Inclusion Complexes ◽  
Biological Activities ◽  
Solubility Diagram ◽  
Dynamics Simulation ◽  
Phase Solubility ◽  
Free Energies ◽  
Scanning Calorimetry ◽  
Host Interaction ◽  
Vdw Force

The aim of this work is to improve physical properties and biological activities of the two flavanones hesperetin and naringenin by complexation with β-cyclodextrin (β-CD) and its methylated derivatives (2,6-di-O-methyl-β-cyclodextrin, DM-β-CD and randomly methylated-β-CD, RAMEB). The free energies of inclusion complexes between hesperetin with cyclodextrins (β-CD and DM-β-CD) were theoretically investigated by molecular dynamics simulation. The free energy values obtained suggested a more stable inclusion complex with DM-β-CD. The vdW force is the main guest–host interaction when hesperetin binds with CDs. The phase solubility diagram showed the formation of a soluble complex of AL type, with higher increase in solubility and stability when hesperetin and naringenin were complexed with RAMEB. Solid complexes were prepared by freeze-drying, and the data from differential scanning calorimetry (DSC) confirmed the formation of inclusion complexes. The data obtained by the dissolution method showed that complexation with RAMEB resulted in a better release of both flavanones to aqueous solution. The flavanones-β-CD/DM-β-CD complexes demonstrated a similar or a slight increase in anti-inflammatory activity and cytotoxicity towards three different cancer cell lines. The overall results suggested that solubilities and bioactivities of both flavanones were increased by complexation with methylated β-CDs.

Elucidation of the complexation mechanism between (+)-usnic acid and cyclodextrins studied by isothermal titration calorimetry and phase-solubility diagram experiments

2009 ◽  
Vol 22 (3) ◽  
pp. 232-241 ◽  
Author(s):  
Freimar Segura-Sanchez ◽  
Kawthar Bouchemal ◽  
Geneviève Lebas ◽  
Christine Vauthier ◽  
Néréide S. Santos-Magalhaes ◽  
...  
Keyword(s):  
Isothermal Titration Calorimetry ◽  
Usnic Acid ◽  
Solubility Diagram ◽  
Titration Calorimetry ◽  
Phase Solubility ◽  
Complexation Mechanism ◽  
Phase Solubility Diagram
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