Chromatographic hydrophobicity index

Valko, K., Bevan, C., Reynolds, D. Chromatographic hydrophobicity index by fast-gradient RP-HPLC a high-throughput alternative to log P/log D. Anal. Chem. 1997, 69, 2022-2029. 

Valko, K., Siegel, P. New chromatographic hydrophobicity index ( /o) based on the slope and the intercept of the logk versus organic phase concentration plot. J. Chromatogr. 1993, 637,49-61. 

Camurri, G., Zaramella, A. High-throughput liquid chromatography/mass spectrometry method for the determination of the chromatographic hydrophobicity index. Anal. Chem. 2001,... 

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. 

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... 

Valko K, Bevan C, Reynolds D (1997) Chromatographic Hydrophobicity Index by Fast-Gradient RP-HPLC A High-Throughput Alternative to log P/log D. Anal Chem 69 2022... 

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

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. 

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... 

CHI index = chromatographic hydrophobicity index chromatographic descriptors... 

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 ... 

Source Valko, K., et al. "Chromatographic Hydrophobicity Index by Fast Gradient RP-HPLC A High Tliroughput Alternative to P/logD." Analytical Chemistry, 691997,2022-2029. As an interesting tidbit, this article has a comprehensive table of lipophilicity values that can be useful in designing extractions. 

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