2-Octanol solid support

Several manufacturers introduced products amenable for this solid-supported LLE and for supported liquid extraction (SLE). The most common support material is high-purity diatomaceous earth. Table 1.8 lists some commercial products and their suppliers. The most widely investigated membrane-based format is the supported liquid membrane (SLM) on a polymeric (usually polypropylene) porous hollow fiber. The tubular polypropylene fiber (short length, 5 to 10 cm) is dipped into an organic solvent such as nitrophenyl octylether or 1-octanol so that the liquid diffuses into the pores on the fiber wall. This liquid serves as the extraction solvent when the coated fiber is dipped... 

Reversed phase HPLC methods have many supporters who insist that careful application of this technique can deliver log Poct values very reliably (Klein, 1988). When the stationary support is octanol-saturated silica, the process most nearly imitates the completely solvated distribution between phases (Mirrlees, 1976), but great care must be taken to avoid "channeling" in the solid support, especially for hydrophobic solutes where column length is short. 

Reversed-phase thin layer chromatography (RP-TLC) is a simple and rapid method for the estimation of a hydrophobic parameter (i rn) without the need of expensive equipment. In this method, the compound is adsorbed on a solid support (usually silica or alumina) and an aqueous phase (with varying amounts of water and 1-octanol mixture) is used as the mobile phase. It has already been established that values are linearly related to the log Poet values and, therefore, Rm values are analogous to the log Poet values.4 values are determined from the measured Rf values and defined by equation (7.6) 44 45... 

Technical details, including solid support, coating and column filling techniques, eluents, and factors affecting the reproducibility have been reviewed [173, 235, 236]. Lipophilicity values from HPLC measurements are not on a unique scale, but the log k values can be converted to -octanol/water partition coefficients with the help of a set of HPLC calibration standard compounds for which classical shake-flask partition coefficients are known. Experience shows once the HPLC method is successfully established in a laboratory, it will remain the method of choice for lipophilicity determinations. 

Immobilized artificial membranes (lAM) are solid membrane mimetics that are covalently bound to the surface of a silica chromatographic support to generate a phospholipid monolayer. lAM chromatography can be applied to measure membrane partitioning of a given compound or to predict bile salt-membrane interactions they may also be used in studies on transcellular absorption. Artificial membranes appear to be well correlated with 1-octanol/water partition coefficients however, since the latter can be well predicted in silico, the real value of AIMs is the ability to study complex molecules or extracts, where in silico prediction is poor. I AM can also be applied to generate large data sets, that in turn can be applied to train and, therefore, improve in silico models by an extensive data input [41]. 

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