Talk:Aqueous normal-phase chromatography

Redirect
Ciccone, I notice that you've redirected "Aqueous Normal Phase Chromatography" to this article, so that "it will be easier for viewers to find". Actually, I'd think it'd be easier to find it the other way -- after all, we look for "High Performance Liquid Chromatography" rather than "High Performance Liquid". Would it be all right if I reverse the redirect (point "Aqueous Normal Phase" to "Aqueous Normal Phase Chromatography")? -- Jaeger5432 | Talk 20:41, 1 January 2007 (UTC)

Jaeger- I would keep it the way it is, since ANP is better understood as an error. I edited it the following way: Normal phase chromatography, an adsorptive mechanism, is used for the analysis of solutes readily soluble in organic solvents based on their polar differences such as amines, acids, metal complexes, etc., while reversed phase, a partition mechanism, is typically used for non-polar differences.Heckendorf 12:53, 20 March 2007 (UTC)

A third type of silica has been developed, using stationary phases based on hydride surfaces. It has been incorrectly referred to as aqueous normal phase chromatography (ANP) for two fundamental reasons, the first of which is that ANP more appropriately describes HILIC chromatography, where water must be present to permit the partitioning of solutes in a "normal phase" order. Secondly, it has been shown in publications studying the derivatization of hydride surfaces, that the "normal phase' character is the result of residual siilanol groups, rather than the fundamental contribution of the hydride. If the (mixed) hydride phase is end capped, then the retention by polar groups decreases, indicating the unique performance is not from the hydride. This is similar to the Hearn observation of increased retention under high acetonitrile (ACN) on acidic, silica based, reversed phase columns, a U-shaped plot of retention versus ACN concentration. Heckendorf 12:14, 20 March 2007 (UTC)

The above statement is completely false. There is no published evidence to prove what the responder has stated. In fact all published work proves just the opposite and all experimental work collected in many labs around the world supports the orignial statements describing ANP. ANP is distinctly differentl from HILIC. If the responder has any published evidence to the contrary he should cite these articles. —Preceding unsigned comment added by 75.7.13.223 (talk) 04:46, 31 January 2008 (UTC)

I removed "What is Aqueous Normal Phase" from See Also, as it was a link to advertising content. It would be better to link to the Knut Irgum review paper on HILIC and ANP instead. Heckendorf 12:55, 2 May 2007 (UTC)

The assumption stated above that the silica hydride surface has no influence on the aqueous normal phase behavior in these phases is false and proven by numerous experiments in a variety of labs. First ANP is distinctly different than HILIC where water is necessary on the surface. The main factors that refute the claim of both being the same are the very fast re-equilibration of silica hydride phases when using gradient analysis (five min or less) and the high reproducibility of the phases in isocratic and gradient ANP. Another strong piece of evidence that silica hydride phases are not dependent on a water layer at the surface can be gained from organic normal phase experiments. Here no extra drying of solvents is necessary and no measures must be taken to protect the solvents from the atmosphere and under these circumstances reproducible isocratic and gradient analysis can be obtained. A ordinary silica phase requires extra measures to be taken to exclude water in order to obtain reasonably reproducible retention. Finally NMR data also indicates that the solvent layer at the surface of a silica hydride phase is different from an ordinary silica-based material. —Preceding unsigned comment added by 75.7.13.223 (talk) 22:29, 29 January 2008 (UTC)