Retention mobile phase

Flow of Mobile Phase Retention Time in Plate Volumes... 

MeOH in mobile phase Retention time R (min) Capacity factor k Log k ... 

An increase in temperature decreases the viscosity and hence increases the EOF. Thus, for a given voltage, more rapid analysis is possible. Temperature also affects the solute partitioning between the mobile and stationary phases and therefore the chromatographic retention. The distribution of the solute between the mobile and stationary phases is a function of its solubility in the liquid phase and adsorption on the solid stationary phase. This is characterized by the distribution ratio K defined as the ratio of the concentration of the solute in the stationary phase to its concentration in the mobile phase. Retention factors are influenced by increasing column temperature because of the increased partition into the mobile phase according to the Van t Hoff equation ... 

From the Snyder-Soczewinski model (12, 13), the entire adsorbent surface is covered by an adsorbate monolayer that consists of mobile phase. Retention is assumed to occur as a displacement process in which an adsorbing solute molecule X displaces some number n of previously adsorbed mobile-phase molecules S... 

LAC at the critical point can be classified as the fifth type of NELC. Operating in the region between size exclusion and adsorption modes of LC by changing the composition of the bicomponent mobile phase, retention becomes independent of polymer size and the separation is accomplished exclusively by composition (20). This technique was applied to the characterization of block polymers (2J). 

In pure micellar mobile phases, retention is described by a hyperbolic relationship. - ... 

Pyka separated 16 PAHs (naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo [a] anthracene, chrysene, benzo[/>]fluoranthene, benzo[fe]fluoranthene, benzo[a]py-rene, dibenzo[a,/z]anthracene, benzo[g,/i,i]perylene, and indeno[l,2,3-C(i]pyrene) according to the Environmental Protection Agency (EPA) by gradient HPLC on a LiChrospher PAH column using acetonitrile and water as mobile phases. Retention times fr (sec) of investigated PAHs were correlated with topological indices based on the adjacency matrix (M, 012) and the... 

Linear mobile-phase velocity Volume of mobile phase Retention factor... 

Retention factor A measure of the amount of time an analyte spends in the stationary phase relative to the mobile phase Retention time The time taken for an analyte to travel from the point of injection to the point of detection within an HPLC system Reverse phase chromatography Describes the chromatographic separation in which the stationary phase is nonpolar and the mobile phase is composed of an aqueous, moderately polar liquid Robustness A measure of a method s ability to withstand small but deliberate changes in the method parameters it provides an indication of its reliability during normal usage Selectivity factor See separation factor... 

Bonded human blood serum has an even more restricted application range than CBH. It is also used in the reversed phase mode with mixtures of phosphate buffers and organic modifiers such as 2-propanol as the mobile phase. Retention and selectivity can be adjusted in the same manner as AGP and CBH. 

Snyder and co-workers [606] studied the retention of benzyl alcohol, m-nitroacetophenone, 10 substituted naphthalenes, chrysene, and perylene on a 30°C diol column using a series of isocratic dichloromethane/hexane (0/100 to 35/65) mobile phases. Retention results for all compounds at various isocratic mobile phase compositions are tabulated. Five steroids (prednisone, corticosterone, adrenosterone, 4-androstene-17a-ol-3-one, and 4-androstene-17j5-ol-3-one) were similarly studied but at ranges of dichloromethane from 13% to 80%. Also presented in this work is an equation from which the eluotropic strength of an A -F B solvent mixture, i.e.. 

Hexamethylpropyleneamine oxime (HMPAO) stereoisomers and their technetium-99m complexes were resolved on a 40°C Chiralcel OD column [614]. The d- and /-uncomplexed isomers were separated in 20 min using a 97/3 hexane/IPA (0.01% diethylamine) mobile phase. The ""Tc complexes were also resolved but with an 85/15 hexane/IPA mobile phase. Temperature increases from 20°C to 40°C greatly improved peak shape and resolution. A table of resolution for the Tc complexes of meso-, d- and /-HMPAO was generated for 90/10 to 0/100 hexane/IPA mobile phases. Retention times for 65/35 to 85/15 hexane/IPA were also tabulated. For all these mobile phases the retention times were under 15 min. 

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