Hi dx a2 ORf dx z ZoRf

Figure 7 Plot of time necessary to ascend 4 cm versus percentage of water in mixtures of methanol/water and acetonit-rile/water. acetonitrile; O, methanol. Plate LiChrosorb RP-18 (7 |im).

The value of cos 6' decreases rapidly as the percentage of water increases. When 6' is close to 90° the solvent is unable to ascend the plate. Even when using a relatively nonviscous organic solvent such as acetonitrile, 30% of water is the upper limit.

In Figure 7, the variation of 4 cm development time with percentage of water is reported, showing the very steep rise of the curve. Analysis may last more than 1 h, which is undesirable. The differences that occur with chain length are rather small but the sequence RP 2 < RP 8 < RP 18 is observed. A compromise between the extended hydrophobicity of a totally modified RP phase and the strong hy-drophilic character of unmodified silica has been found with layers prepared with a lower degree of silanization. These layers are completely water wett-able (WF plates) and permit the ascent of mobile phases with high water content.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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