University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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Partition coefficients

Classification: Chemical constant -> Partition coefficients

Citations 9

"Determination Of Octanol-water Partition Coefficients Using A Micro-volume Liquid-liquid Flow Extraction System"
Anal. Chim. Acta 2000 Volume 423, Issue 1 Pages 137-144
Karin Carlsson and Bo Karlberg

Abstract: An extraction system consuming less than 1 µl of sample and organic solvent (combined volume) has been developed for the determination of 1-octanol-water partition coefficients (log K-ow). The system comprises a capillary, a micro-volume stepper piston pump, a peristaltic pump and a detector. The stepper piston pump is programmable, enabling full control and selection of each step in the pumping sequence. Coupled to the pump is a 250 µm i.d. silica capillary, extending 240 mm from its aperture to the detector cell which houses an on-capillary spectrophotometric detector allowing direct monitoring of both the aqueous sample and the organic solvent plugs. Programmed portions of air, aqueous sample, organic solvent and a second portion of air are sequentially introduced into the capillary from respective vials. Typically, 250 nl of both the aqueous sample and organic solvent were introduced in the trials reported here. Since all liquids are aspirated directly into the capillary there is no need to pre-flush the system (as is required in most other continuous flow systems). Thus, the entire portions of the sample and the organic solvent are used in the analysis. The analytical procedure used for determining octanol-water partition coefficients is essentially an automated and miniaturised version of the batch method recommended in the OECD manual. The log K-ow values obtained agreed well with literature data and/or manual batch determinations. Typical analysis time was 4 min when applying a mean flow rate of about 4 µl min-1, including a wash cycle between the samples. The system is suitable for screening purposes and could readily be automated using a robot.
1-Octanol Water Spectrophotometry

"Interfacial Enzyme Partitioning As A Tool For Constructing Biosensors"
Acta Aliment. 1999 Volume 28, Issue 4 Pages 329-338
N. Adányi, Szamos, J., M. Váradi

Abstract: To explore new possibilities of enzyme immobilization, we investigated bioactive layers prepared by a new procedure based on three-phase partitioning (TPP) of proteins. By this method a third phase or midlayer as a protein layer can be developed at the interface of a protein system containing two phases (organic solvent/aqueous salt solution). Proteins of meat origin partitioned together with bioselective material (e.g. an enzyme) after centrifugation resulted in excellent bioactive layers. In the newly developed sensor, glucose oxidase was immobilized in a layer, which was fixed on the surface of a platinum ring electrode. The biosensor was built in a flow injection analyzer (FIA) system, where the hydrogen peroxide generated during the enzymatic reactions was determined by an amperometric cell. The parameters for biochemical and electrochemical reactions (ion concentration and pH of buffer, flow rate) were optimized. The linear range of analysis by the newly developed sensor was from 0.5 to 10 mmol L-1 glucose. The biosensor could be used for more than 300 analysis.
Glucose Biological tissue Amperometry Sensor

"Determination Of Octanol/water Partition Coefficients By Flow Injection Analysis"
Anal. Chim. Acta 1988 Volume 214, Issue 1 Pages 315-328
S. J. Gluck

Abstract: Determination of octanol/water partition coefficients by batch-extraction methods is currently the only acceptable procedure for application to structure/activity relationships. Work on the development of flow-injection systems to determine these partition coefficients is reported. It is shown that it is not necessary to know the concentration of the analytic in either phase; the partition coefficient should be equal to the differences in the octanol and water peak widths divided. by the system residence time. For a limited number of compounds, this is shown to be valid. Several systems were developed, including a flow-through dialyzer which was 5 times more efficient than the best commercial unit.
Sample preparation

"Determination Of Octan-1-ol Water Partition Coefficients By Flow Injection Extraction Without Phase Separation"
Anal. Chim. Acta 1991 Volume 248, Issue 2 Pages 493-499
V. Kubán

Abstract: Single-channel coaxial segmenters were used for the introduction of an aqueous or octan-1-ol solution of an organic substance directly into a continuous flow of the other solvent. The analytical signal was measured simultaneously on both aqueous and organic phase segments by an 'on-tube' fast-reading spectrophotometric detector (ca. 3 ms time resolution) and treated mathematically. The octan-1-ol-water phase signal ratio corresponds to the partition coefficient of the organic substances. The applicability of the method is demonstrated by the determination of partition coefficients of phenol, citric acid, acetylsalicylic acid and sodium salicylate.
1-Octanol Water Sample preparation

"Evaluation Of Partition Measurements In Liquid-liquid Segmented Flow"
Talanta 1994 Volume 41, Issue 8 Pages 1377-1382
Lars-Göran Danielsson and Zhang Yu-Hui,

Abstract: Equations are presented for the calculation of partition coefficients determined by two-phase FIA. The equations were demonstrated with the injection of 20 µL metoprolol, p-hydroxybenzaldehyde, p-nitrophenol, phenol, propranolol and p-toluidine in CHCl3 or 0.15 M phosphate buffer of pH 5-6 into a carrier stream of CHCl3 or buffer and subsequently mixed in a PTFE reaction coil (2 m x 0.5 mm i.d.). The two phases were pumped at a total flow rate of 0.21-3.7 ml/min and the organic and aqueous phases separated under N2 using 0.2 and 0.22 µm PTFE and poly(vinylidene fluoride) membranes. The absorbance of the separated phases was determined by spectrophotometry. The product of carrier flow rate and peak area RSD was 0.87% (n = 11). Separation efficiencies of 80-90% and 40-50% were obtained for the hydrophobic and hydrophilic membranes, respectively.
Metoprolol 4-hydroxybenzaldehyde 4-Nitrophenol Phenol Propranolol 4-Toluidine Spectrophotometry Sample preparation

"Mechanized Method For Measuring Metal Partition In N-octanol-aqueous Systems. Partition Of Aluminum Complexes"
Analyst 1995 Volume 120, Issue 10 Pages 2513-2519
Lars-Göran Danielsson, Yu-Hui Zhang and Anders Sparén

Abstract: A continuous-flow extraction system combined with electrothermal (ET) AAS for the measurement of n-octanol/H2O partition constants (D') of metal complexes is described. A stream (0.2 ml/min) of the aqueous sample solution was merged with a stream (0.1 ml/min) of n-octanol in a segmentor. The mixture was passed through a PTFE extraction coil (1 m x 0.5 mm i.d.) and then into a gravitational (non-membrane) phase separator (diagram given). The separated n-octanol phase was subsequently injected into an air stream and carried to the ETAAS instrument for metal determination. A diagram of the system used is given. The D' value was evaluated from the ratio of the metal concentration in n-octanol to that in aqueous solution. The RSD was 10%. The throughput was 3 samples/h. The method was used to study the partition of aluminum citrate complexes to n-octanol. D' values for Al in supernatant solutions from rat-feed slurries, obtained from in vitro studies of gastro-intestinal absorption, were also measured. Results are discussed.
Aluminum Rat Feed Spectrophotometry Sample preparation

"Rapid Determination Of Conditional Partition Constants In An FIA System"
J. Pharm. Biomed. Anal. 1992 Volume 10, Issue 6 Pages 405-412
L. -G. Danielsson*, L. Nord and Zhang Yu-hui

Abstract: This paper presents a simple and rapid method for the screening of substances for their conditional partition constants in the chloroform-water system. Samples are injected in either aqueous or organic solution into the corresponding phase. After equilibration in segmented flow, the the amt. of samples remaining is measured photometrically. Performing the measurements at a series of phase volume ratios enables calculation of conditional partition constants knowing neither the amount injected nor the absorptivity of the substance under study. The time needed for a determination is about 15 min per substance, in many cases even shorter and the sample consumption is, in most cases, less than 1 mg. These characteristics make the method suitable for screening purposes. A series of compounds has been examined with this method, and acceptable results for the conditional partition constants were obtained in the range 0.2 < D' < 100 (-0.7 < log D' < 2.0).
Sample preparation

"Mechanized Determination Of N-octanol/water Partition Constants Using Liquid-liquid Segmented Flow Extraction"
J. Pharm. Biomed. Anal. 1994 Volume 12, Issue 12 Pages 1475-1481
Lars-G&ouml;ran Danielsson* and Zhang Yu-Hui

Abstract: In the cited flow injection method, analytes (acetic acid, caffeine, p-toluidine, 2,5-dinitrophenol or alprenolol) were dissolved in water and portions (25 µL) were injected into a stream of water which was then segmented with a stream of n-octanol. After passage through an extraction coil, a portion of the aqueous phase was separated with use of a cellulose nitrate/cellulose acetate (0.45 µm) or PVDF (0.22 µm or 0.1 µm) hydrophilic membrane and analyzed spectrophotometrically. The flow injection manifold was similar to that described previously (cf., Talanta, 1994 41, 1377). Partition coefficients were calculated by varying the phase flow rates. A simplified method involving only two measurements is described. The results agreed well with literature values obtained by the shake-flask method and the RSD were 15%. Phase separation efficiencies at various flow rates are tabulated. The assay time was 15 min.
Acetic acid Caffeine 4-Toluidine 2,5-Dinitrophenol Alprenolol Spectrophotometry Sample preparation

"Estimation Of Partition-coefficients Using FIA And Flow-through Membrane Electrodes"
Chem. Anal. 1991 Volume 36, Issue 5-6 Pages 855-861
Blaskiewicz, T.;Staroscik, R.;Zaleska, E.

Abstract: The selectivity coefficients of electrodes based on tricaprylmethylammonium ion pairs in decanol were correlated with the octanol-water partition coefficients for several barbiturates under optimized flow conditions. A fair correlation between the selectivity coefficients, detection limit, and octanol-water partition coefficients was found. (SFS)
Electrode Electrode