Effect of Solvent Vaporization

The observation of most TLC spots shows that solute distribution is not uniform. Precise data have been collected by Hezel and Belenkii, who used a microtome to cut layers 0.05 mm thick. There is a radial flow of liquid phase, which explains why the material in spots is on the surface of the plate, the band being thinner than the layer itself. When a plate is wetted by the mobile phase, vaporization occurs, the flux of which is given by:

By combination of the above equations and rearrangement:

dt e

Integration of this second-order equation and two terms expansion gives:

Equation [27] is valid if the rate of vaporization is small compared to the flow rate inside the layer bed. This is true since from Van Brakel's data the evaporation expressed in terms of the velocity of the rising front is about 0.5 mm day-1 with toluene or water. A loss of 1% min"1 is reasonable.

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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