Chromatographic Hydrophobicity Index CHI

The retention depends on the nature of both the stationary phase and the organic modifier in the mobile phase. Therefore CHI values obtained using different systems show different sensitivities towards solute characteristics. This has been studied systematically and used for the quantitative calculation of solute molecular descriptors (H-bond donor capacity, H-bond acceptor capacity and dipolarity/polarizability) for application in a general solvation equation [21]. [Pg.29]

Valko et al. [37] developed a fast-gradient RP-HPLC method for the determination of a chromatographic hydrophobicity index (CHI). An octadecylsilane (ODS) column and 50 mM aqueous ammonium acetate (pH 7.4) mobile phase with acetonitrile as an organic modifier (0-100%) were used. The system calibration and quality control were performed periodically by measuring retention for 10 standards unionized at pH 7.4. The CHI could then be used as an independent measure of hydrophobicity. In addition, its correlation with linear free-energy parameters explained some molecular descriptors, including H-bond basicity/ acidity and dipolarity/polarizability. It is noted [27] that there are significant differences between CHI values and octanol-water log D values. [Pg.416]

Valko et al. have developed chromatographic methods which are based on established reversed phase methods with acetonitrile water gradients. The lipophilicity is characterized as a so-called chromatographic hydrophobicity index (CHI), which approximates the percentage of acetonitrile necessary for equal distribution between mobile and stationary... [Pg.408]

Fig. I2.lt). The plot of the chromatographic hydrophobicity index (CHI) values obtained on Inertsil ODS and lAM column (from Ref. 64 ).

Based on the cpo concept, a fast gradient method RP-HPLC has been proposed to determine the chromatographic hydrophobicity index (CHI) as a high-throughput alternative to other lipophilicity measures.Eor this... [Pg.195]

Based on the (po concept, a fast gradient method RP-HPLC has been proposed to determine the chromatographic hydrophobicity index (CHI) as a high-throughput alternative to other lipophilicity measures.For this purpose, gradient retention times (tg) are measured and converted to CHI values by means of a calibration equation, derived by a set of standards with well-determined CHI (tpo) values ... [Pg.1403]

Fig. 12.19) that seemed to have the widest range of coefficients for the molecular descriptors in the solvation equation. Table 12.10 shows the solvation equations obtained and their normalised coefficients. The equations were obtained from the chromatographic hydrophobicity index data (CHI) of the compounds listed in Table 12.7 by using a 2.5 min linear gradient of the oi anic solvent from 0 to 1009F with 2 ml/min flow rate. The columns used were 4.6 x 50 mm short columns. The application of this fast gradient method makes it possible to obtain CHI values in a given HPLC system in 5 min. [Pg.586]

CHI index = chromatographic hydrophobicity index chromatographic descriptors... [Pg.126]