High-performance liquid hydrophobic effect

Lau, S. Y. M., Taneja, A. K., and Hodges, R. S., Effects of high-performance liquid chromatographic solvents and hydrophobic matrices on the secondary and quaternary structure of a model protein. Reversed-phase and size exclusion high-performance liquid chromatography, /. Chromatogr., 317, 129, 1984. 

Burke, T.W., Mant, C.T., Black, J.A., Hodges, R.S. (1989). Strong cation-exchange high-performance liquid chromatography of peptides. Effect of non-specific hydrophobic interactions and linearization of peptide retention behaviour. J. Chromatogr. 476, 377-389. 

Nakagawa, T., Murata, H., Shibukawa, A., Murakami, K., and Tanaka, H. (1985) Liquid Chromatography with Crown Ether-containing Mobile Phases V. Effect of Hydrophobicity and Cavity Size of the Crown Ether on Retention of Amino Compounds in Reversed-phase High-performance Liquid Chromatography, J. Chromatogr. 330, 43-53. 

P. Roumeliotis, A. A. Kurganov, and V. A. Davankov, Effect of the hydrophobic spacer in bonded [Cu(L-hydroxyprolyl)alkyl] silicas on retention and enantiose-lectivity and enantioselectivity of a-amino acids in high performance liquid chromatography. /. Chromatogr. A 266 (1983), 439. 

The experiment was initiated by introducing nitrogen gas from the gas feed line at the head of the rotating column. Then, a 2.5-L volume of the BC solution was continuously introduced into the coil from the sample feed line at 1.5 mL/min. The hydrophobic components produced a thick foam which was carried with the gas stream and collected from the foam collection line at the tail other components stayed in the liquid stream and eluted from the liquid collection line at the head. High-performance liquid chromatographic analysis of the foam fraction revealed that the degree of enrichment increased with the hydrophobidty of the components. These results clearly indicate that the present method will be quite effective for the detection and isolation of small amounts of natural products present in a large volume of aqueous solution. 

In order to investigate the properties of individual fractions of humic substances, various modes of high performance liquid chromatography (HPLC) have been employed. Hydrophobic interaction chromatography (5) has proved to be an effective separation technique, resulting in five distinct humic fractions from one sample. Structural analysis of these fractions was subsequently performed by infrared and nuclear magnetic resonance spectroscopy, and molecular weight distribution was also measured. 

The beneficial effect of the hydrophobicity of [BMIM]PFg was shown to extend to other enzymes a remarkably enhanced enantioselectivity was observed for lipases AK and Pseudomonas fluorescens for the kinetic resolution of racemic P-chiral hydroxymethanephosphinates (Scheme 31) (278). The ee values of the recovered alcohols and the acetates were about 80% when the enzymatic reactions were conducted in the hydrophobic [BMIMJPFg. In contrast, there was little enantioselectivity (<5%) observed with the enzymes in hydrophilic [BMIM]BF4. The lack of stereoselectivity in [BMIM]BF4 was attributed to the high miscibility of [BMIM]BF4 with water. The relatively hydrophilic ionic liquid is capable of stripping off the essential water from the enzyme surface, leading to insufficient hydration of the enzyme and a consequently strong influence on its performance (279). 

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