Search results for "partition coefficient"
showing 10 items of 146 documents
Bimodal copper oxide nanoparticles doped phase for the extraction of highly polar compounds by in-tube solid-phase microextraction coupled on-line to…
2020
Abstract Polymers obtained from tetraethyl orthosilicate (TEOS) and triethoxymethylsilane (MTEOS) have been functionalized with different metal and metal oxide nanoparticles (NPs), and used as coatings of extractive capillaries for the extraction of polar compounds by in-tube solid-phase microextraction (IT-SPME) coupled on-line to nano-liquid chromatography (nano-LC). The extraction capabilities of the new phases have been studied using several triazinic herbicides with log of octanol/water partition coefficients (Kow) ranging from -0.7 to 3.21 under reversed phase chromatographic conditions. Best extraction efficiencies for the most polar compounds (log Kow ≤ 2.3) were typically obtained …
Micellar versus hydro-organic mobile phases for retention-hydrophobicity relationship studies with ionizable diuretics and an anionic surfactant
2004
Abstract Logarithm of retention factors (log k ) of a group of 14 ionizable diuretics were correlated with the molecular (log P o/w ) and apparent (log P app ) octanol–water partition coefficients. The compounds were chromatographed using aqueous–organic (reversed-phase liquid chromatography, RPLC) and micellar–organic mobile phases (micellar liquid chromatography, MLC) with the anionic surfactant sodium dodecyl sulfate (SDS), in the pH range 3–7, and a conventional octadecylsilane column. Acetonitrile was used as the organic modifier in both modes. The quality of the correlations obtained for log P app at varying ionization degree confirms that this correction is required in the aqueou…
Physico-Chemical Interactions in the Flavor-Release Process
2017
The perception of flavor is induced by the release of aroma compounds in the vapor phase. The olfactory perception is not only related to the nature of aroma compounds initially present in the food, but also to their distribution between the different phases. After a description of the interactions established between the aroma compounds and different constituents of food, this chapter looks at physico-chemical characteristics of aroma compounds and at the composition and properties of food matrices. Then, in order to understand the behavior of aroma compounds in the matrices, study methods of interactions are described. The assessment of the release is done by determining the partition coe…
Impact on flavour release of the structure of composite gels containing polysaccharides: Example of the fruit préparations
2006
The main objective of this study was to understand the respective rôle of the structure of a food product and of the physicochemical interactions on flavour release. For that purpose, fruit préparations hâve been chosen as model matrices. Those matrices contain a polysaccharide as gelling agent, a cross-linked waxy corn starch (1.4%), a high sucrose content (35%), an acidic buffer and a strawberry aroma (17 molécules). Four matrices were developed by modifying either the composition or the concentration in gelling agent: two matrices of similar texture containing either LM pectin or carrageenan, and two carrageenan based matrices with différent gelled structures. In a first step; two comple…
Universal Organic Solvent−Water Partition Coefficient Model
1999
A method that permits a semiquantitative estimate of the partitioning of any solute between any two media is presented. As an example, the organic solvent-water partition coefficients P are calculated. Program GSCAP is written as a version of Pascal's SCAP program. The only needed parameters are the dielectric constant and molecular volume of the organic solvent. The log P results are compared with the Pomona database. The average absolute deviation is 1.48 log units and the standard deviation is 1.66 log units.
Study on resolution capacity and secondary mechanisms of three different TSK gels for organic SEC.
2005
A comparative study on the elution behavior in size-exclusion chromatography (SEC) of three polymeric TSK gel packings, named H, H H R , and H X L types, is performed. The deviations of the universal calibration (u.c.) curves of seven solvent-polymer systems show evidence that the existence of secondary effects accompanying the main SEC mechanism. These secondary mechanisms are a consequence of the binary enthalpic interactions between the different components of the chromatographic system, such as polymer-solvent, polymer-gel and solvent-gel. However, in the present case, the observed deviations from a unique u.c. curve can mainly be attributed to adsorption of polymeric solutes (analytes)…
Solution Properties of Poly-Electrolytes. XI. Adsorption Effects in Aqueous Size-Exclusion Chromatog-Raphy of Polyanions
1994
Abstract Elution profiles of a series of polymer standards such as sodium poly(styrene sulphonate), poly(acrylic acid) and poly(L-glutamic acid) have been obtained from size-exclusion chromatography experiments using separately two types of hydrophilic supports. A variety of mobile phase compositions have been performed to enhance adsorption effects in order to study how this phenomenon can affect to the chromatographic separation mechanism of polyanions. Distribution coefficient values, in general greater than unity, have served to quantify the adsorption effect, as well as to analyze their dependence on eluent ionic strength, on the ionic groups of the support and on the chemical nature a…
Atom-based non-stochastic and stochastic bilinear indices: Application to QSPR/QSAR studies of organic compounds
2008
The recently introduced bilinear indices are applied to the QSAR/QSPR studies of heteroatomic molecules. These novel atom-based molecular fingerprints are used to predict the boiling point of 28 alkyl-alcohols and partition coefficient, specific rate constant and antibacterial activity of 34 2-furylethylenes derivatives. The obtained models are statistically significant and show rather very good stability in a cross-validation experiment. The comparison with other approaches exposes a good behavior of our method in this QSPR studies. The obtained results suggest that with the present method, it is possible to obtain a good estimation of physical, chemical and physicochemical properties for …
Effects of dissolved organic matter from a eutrophic lake on the freely dissolved concentrations of emerging organic contaminants
2014
The authors studied the effects of dissolved organic matter (DOM) on the bioavailability of bisphenol A (BPA) and chloramphenicol by measuring the freely dissolved concentrations of the contaminants in solutions containing DOM that had been isolated from a mesocosm in a eutrophic lake. The abundance and aromaticity of the chromophoric DOM increased over the 25-d mesocosm experiment. The BPA freely dissolved concentration was 72.3% lower and the chloramphenicol freely dissolved concentration was 56.2% lower using DOM collected on day 25 than using DOM collected on day 1 of the mesocosm experiment. The freely dissolved concentrations negatively correlated with the ultraviolent absorption coef…
Gas-liquid chromatography as a tool for evaluation of lipophilicity of selected esters of aromatic and aliphatic acids
1986
Abstract The use of gas-liquid chromatographic retention values for the determination of lipophilicity was studied for series of esters of aromatic and aliphatic acids and for series of aliphatic alcohols. The regression relationships between the logarithms of the partition coefficients and the retention characteristics measured on two capillary columns, SE-30 and OV-351, differing markedly in polarity, were evaluated. It may be deduced that, for the structurally similar compounds, the stationary phases used simulate the reference partitioning system octanol-water.