High-performance liquid chromatography retention factor

Guo, D., Mant, C. T., Taneja, A. K., and Hodges, R. S., Prediction of peptide retention times in reversed-phase high-performance liquid chromatography II. Correlation of observed and predicted petide retention times and factors influencing the retention times of peptides, /. Chromatogr., 359, 519,1986. 

Enantiomers of the 8,9-dichloro-2,3,4,4 ,5,6-hexahydro-177-pyrazino[l,2-tf]quinoxalin-5-one (structure 249 Rz = R3 = Cl R1 = R4 = H) could be separated by normal-phase, chiral high-performance liquid chromatography (HPLC) with increased retention and separation factors if ethoxynonafluorobutane was used as solvent, instead of -hexane <2001JCH(918)293>. 

Experimental retention times or capacity factors generated by reverse phase high performance liquid chromatography (RP-HPLC) (Vowles and Mantoura, 1987 Hodson and Williams, 1988 Pussemier et al., 1990 Szabo et al., 1990a,b Hong et al., 1996) also have been correlated with Koc. 

Experimentally determined retention times or capacity factors (k) generated by reverse phase, usually octadecylsilane (ODS), high performance liquid chromatography (RP-HPLC) have been used widely to estimate Kow values (McDuffie, 1981 Haky and Young, 1984 Sarna, 1984 Doucette and Andren, 1988). More recently, this approach has been used to directly estimate Koc (Vowles and Mantoura, 1987 Hodson and Williams, 1988 Szabo et al., 1990 Kordel et al., 1993 Kordel et al., 1995 Hong et al., 1996). This is not strictly an estimation method because it relies on the acquisition of experimental retention times. 

Reversed-phase high performance liquid chromatography (RP HPLC) works by eluates partitioning between mobile and stationary phases, and the retention factor log k is proportional to log Kow. Numerous studies have correlated Koc with log k, and Gawlik et al. (1997) list 35 such correlations, most of which relate to specific chemical classes. Note that the correlations vary with the stationary phase used. Some examples are ... 

System Suitability Chromatograph a suitable number of injections of the Assay Preparation, as directed under Calibration, to ensure that the resolution factor, R, between the major peaks occurring at retention times of approximately 0.50 (8-tocopheryl propionate) and 0.63 ((3- plus y-tocopheryl propionates), relative to hexadecyl hexadecanoate at 1.00, is not less than 2.5 (see System Suitability in High-Performance Liquid Chromatography under Chromatography, Appendix IIA). 

Retention is measiued as either the retention time (Rt) or retention factor (Rf). Rt is used in high-performance liquid chromatography (HPLC) and gas chromatography, whereas Rf is used in paper and thin-layer chromatography. Rf is calculated using the following formula ... 

The LFER-based retention parameter in high-performance liquid chromatography (HPLC) is the logarithm of the phase capacity ratio or retention factor k. The capacity... 

Figure 33-2 shows plots of plate heights // as a function of average linear velocity u in cm/s for high-performance liquid chromatography and supercritical-fluid chromatography. In both cases, the solute was pyrene, and the stationary phase was a reversed-phase octadecyl silane maintained at 40°C. The mobile phase for HPLC was acetonitrile and water, while for SFC the mobile phase was carbon dioxide. These conditions yielded about the same retention factor (k) for both mobile phases. Note that the minimum in plate height occurred at a flow rate of 0.13 cm/s... 

Reversed phase high-performance liquid chromatography (RP-HPLC) is an indirect, rapid, and high throughput method for the determination of partition coefficients. In HPLC, the most frequently used retention factor, k, is defined as ... 

In a high-performance liquid chromatography experiment, the dependence of the retention parameter, k, on three factors was investigated. The factors were pH (factor P), the concentration of a counter-ion (factor T) and the concentration of the organic solvent in the mobile phase (factor C). Two levels were used for each factor and two replicate measurements made for each combination. The measurements were randomized. The table below gives the average value for each pair of replicates. 

K. Biittner, C. Pinilla, J.A. Appel, and R.A. Houghten, J Chromatogr. 625, 191 (1992). P.C. Sadek, Elucidation of the Factors Responsible for Small Solute Retention and Irreversible Protein Binding in Reversed-Phase High Performance Liquid Chromatography, Ph.D. dissertation. University of Minnesota, Minneapolis, 1985,... 

K. Saitoh, Y. Shibata, and N. Suzuki. Factors influencing the retention of rare earth— tetraphenylporphine complexes in reversed-phase high-performance liquid chromatography. Journal of Chromatography A 542 351-363,1991. 

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