Hydrophilic interaction HPLC chromatography

Today, the most rational way to address the separation of very hydrophilic and uncharged compounds in HPLC is by utilizing hydrophilic interaction liquid chromatography (HILIC) [4-7], which is considered to be a variant of... 

Figure 1 Principles of reversed-phase high-performance liquid chromatography (RP-HPLC) and hydrophilic interaction liquid chromatography (HILIC).

Figure 6 Hydrophilic interaction liquid chromatography (HILIC) separation of the taste-active subfraction FI of an acid-deamidated wheat gluten hydrolysate that was not retained by reversed-phase high-performance liquid chromatography (RP-HPLC). Fru-Val, A -(l-deoxy-D-fructos-l-yl)-valine Fru-Glu, A -(l-deoxy-D-fructos-l-yl)-glutamic acid (cf. Fig. 7).

A new topic is now included Chapter 20 about quahty assurance. Part of it could be found before in chapter 19 but now the subject is presented much broadly and independent of Analytical HPLC . Two chapters in the appendix were updated and expanded by Bruno E. Lendi, namely the ones about the instrument test (now chapter 25) and troubleshooting (now chapter 26). Some new sections were created 1.7, comparison of HPLC with capillary electrophoresis 2.11, how to obtain peak capacity 8.7, van Deemter curves and other coherences 11.3, hydrophilic interaction chromatography 17.2, method transfer 18.4, comprehensive two-dimensional HPLC 23.3, fast separations at 1000 bar 23.5, HPLC with superheated water. In addition, many details were improved and numerous references added. 

High-performance liquid chrottHtogtaphy (HPLC), definition. 3 HlUC, 217-223 HPLC, definition, 3 Hydrodynamic chromatography, 142 Hydrolytic stability, 107,346,369-370 Hydrophilic interaction (HlUC), 5,135,136, 217-223... 

McCalley, D.V. (2011) Hydrophilic interaction chromatography is it a viable complementary method to reversed-phase for the separation of polar or ionizable compounds Presentation TOl at HPLC 2011, Budapest, Hungary. 

Nowadays, almost all commercially available HPLC stationary phases are also applicable to planar chromatography. In addition to the polar hydroxyl groups present on the surface of native silica, other polar functional groups attached to the silica skeleton can also enter into adsorptive interactions with suitable sample molecules (34). Silica with hydrophilic polar ligands, such as amino, cyano, and diol functions, attached to the silica skeleton by alkyl chains, all of which have been well proven in HPLC, have also been developed for TLC (34). 

Normal phase (NP) separations are comparatively rarely used in environmental analysis. Again, the reasons lie in the range of analytes amenable to this mode of separation, and in the limited compatibility of typical normal phase HPLC (NP-HPLC) mobile phases with mass spectrometric detection (this also applies to IC). Not only for this reason has interest recently grown in hydrophilic-lipophilic interaction chromatography (HILIC), which represents a viable alternative to the separation of very polar compounds with mobile phases that have a much better compatibility with MS detection, for example, acetonitrile/water with a low water content, typically below 10%, 32 Nonetheless, NP chromato-graphy retains its important role in sample preparation, particularly for the cleanup of complex environmental samples. In the off-line approach, fractions are collected and the relevant one is injected into the reversed phase HPLC (RP-HPLC) system, often after solvent exchange. 

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