Partition coefficients, chromatography

Elution volume, exclusion chromatography Flow rate, column Gas/liquid volume ratio Inner column volume Interstitial (outer) volume Kovats retention indices Matrix volume Net retention volume Obstruction factor Packing uniformity factor Particle diameter Partition coefficient Partition ratio Peak asymmetry factor Peak resolution Plate height Plate number Porosity, column Pressure, column inlet Presure, column outlet Pressure drop... 

By modeling the substance behavior at the interface of two liquid phases, in particular, stationary and mobile phases in liquid chromatography, 1-octanol - water partition coefficients or partition coefficients in... 

The lipophilicity (7 m value) and specific hydrophobic surface area of pyrido[l,2-a]pyrazinium-l-olates 342 and -3-olate 343, and l-(4-chlorophe-nyl)-l-hydroxy-l,2-dihydropyrazino[2,l-a]isoquinolinium salt (344) has been measured by reversed-phase thin-layer chromatography (98MI13). Partition coefficient (log/ ) of 9-bromo-5-[(A-phenylaminocarbonyl)-methyl]-l,2,3,5,6,7-hexahydropyrido[l,2,3- fc]quinoxaline-2,3-dione was calculated to be 2.78 (97JMC4053). 

Palladium, D. of as dimethylglyoximate. (g) 463 as nioximate, (g) 474 by EDTA, (ti) 329 Paper chromatography 229 see Thin layer chromatography Parallax errors due to, 85 Parallel determinations 132 Partial ionic equations 850, (T) 851 Partition chromatography 13. 217 Partition coefficient 162 Patton and Reeder s indicator 317, 328 Peptisation 419. 421... 

Squire [364] and Porath [300,301] developed geometrical pore models for gel chromatography media. Squire considered a gel with a set of conical, cylindrical, and rectangular crevices, and found the pore volume, assumed equal to the partition coefficient K y, to vary as... 

In contrast to straight phase or adsorption chromatography, partition chromatography involves the separation of sample molecules owing to their different partition coefficients between the liquid stationary and mobile phases. The liquid stationary phase is located in the pores of a sorbent, ideally only acting as a support, making no contribution to the retention of the sample molecules. 

Lipophilicity represents the affinity of a molecule or a moiety for a lipophilic environment. It is commonly measured by its distribution behavior in a biphasic system, either liquid-liquid (e.g. partition coefficient in 1-octanol-water) or solid-liquid (retention on reversed-phase high-performance liquid chromatography or thin-layer chromatography system). 

Trone, M. D., Leonard, M. S., Khaledi, M. G. Congeneric behavior in estimations of octanol-water partition coefficients by micellar electrokinetic chromatography. Anal. Chem. 2000, 72, 1228-1235. 

Sangster, J. Octanol-Water Partition Coefficients Fundamentals and Physical Chemistry, Wiley, Chichester, 1997. n Valko, K. Application of high-performance liquid chromatography based measurements of lipophilicity to model biological distribution. J. Chromatogr. A 2004, 1037, 299-310. 

R. B. Screening of octanol-water partition coefficients for pharmaceuticals by pressure-assisted microemulsion electrokinetic chromatography. 

Ostergaard, J., Hansen, S. H., Larsen, C., Schou, C., Heegaard, N. H. Determination of octanol-water partition coefficients for carbonate esters and other small organic molecules by microemulsion electrokinetic chromatography. Electrophoresis 2003, 24, 1038-1045. 

Poole, S. K., Patel, S., Dehring, K., Workman, H., Dong, J. Estimation of octanol-water partition coefficients for neutral and weakly acidic compounds by microemulsion electrokinetic chromatography using dynamically coated capillary columns. J. Chromatogr. 

Razak, J. L., Cutak, B. J., Larive, C. K., Lunte, C. E. Correlation of the capadty factor in vesicular electrokinetic chromatography with the octanobwater partition coefficient for charged and neutral analytes. Pharm. Res. 2001, 18, 104-111. 

Klotz, W. L., Schure, M. R., Eoley, J. P. Rapid estimation of octanol-water partition coefficients using synthesized vesicles in electrokinetic chromatography. J. Chromatogr. A 2002, 962, 207-219. 

The following physico-chemical properties of the analyte(s) are important in method development considerations vapor pressure, ultraviolet (UV) absorption spectrum, solubility in water and in solvents, dissociation constant(s), n-octanol/water partition coefficient, stability vs hydrolysis and possible thermal, photo- or chemical degradation. These valuable data enable the analytical chemist to develop the most promising analytical approach, drawing from the literature and from his or her experience with related analytical problems, as exemplified below. Gas chromatography (GC) methods, for example, require a measurable vapor pressure and a certain thermal stability as the analytes move as vaporized molecules within the mobile phase. On the other hand, compounds that have a high vapor pressure will require careful extract concentration by evaporation of volatile solvents. 

R. -S. Tsai, P.-A. Carrupt, and B. Testa, Measurement of Partition Coefficients Using Centrifugal Partition Chromatography. Method Development and Application to the Determination of Solute Properties, American Chemical Society, Washington DC, 1995, pp. 143-154. 

In gas chromatography the value of the partition coefficient d ends only on the type of stationary phase and the column temperature. It is independent of column type and instrumental parameters. The proportionality factor in equation (l.ll) is called the phase ratio and is equal to the ratio of the volume of the gas (Vg) and liquid (V ) phases in the column. For gas-solid (adsorption) chromatography the phase ratio is given by the volume of the gas phase divided by the surface area of the stationary phase. 

Krikorian SE, Chom TA, King JW. 1987. Determination of octanol/water partition coefficients of certain organophosphorus compounds using high-performance liquid chromatography. Quant Struct-Act Relat 6(2) 65-69. 

A method where phospholipids are entrapped in the pores of resin beads, in the forms of multilamellar vesicles, has been described [313-319,376]. In some ways, the idea is similar to that of IAM chromatography, even though the resin is modified differently. The retention indices correlate very well with the partition coefficients measured in liposome-water systems (described below). 

Centrifugal partition chromatography (CPC) has been used to characterize the partitioning behavior of hydrophilic molecules, where log D values as low as —3 can be obtained [371,377-379]. It is not as popular a method as it used to be, apparently due to instrumental challenges. Cyclic voltammetry (CV) has become the new method used to get access to very low log D values, with partition coefficients reported as low as —9.8 [261,269,362]. 

Ong, S. Liu, H. Pidgeon, C., Immobilized-artificial-membrane chromatography Measurements of membrane partition coefficient and predicting drug membrane permeability, J. Chromatogr. A 728, 113-128 (1996). 

Bums, S. T. Khaledi, M. G., Rapid determination of liposome-water partition coefficient (Kiw) using liposome electrokinetic chromatography (LEKC), J. Pharm. Sci. 91, 1601— 1612 (2002). 

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