Tuesday, February 08, 2005

Boring day in lab

Well, if I'm going to blog, I have to stick with it, even if it means pumping out crappy copy just to get into practice. Today I washed a lot of glassware. Woo woo. I also did some chromatography.

Today I sucessfully separated a three-component mixture into its parts with a silica gel chromatography column. The column consists of a vertical tube filled with silica gel (just like the silica in those little capsules in vitamin bottles that say "Do not eat") and hexane. The reason they put silica in vitamin bottles is related to the reason I put silica in my chromatography column. Silica is a very polar compond. It it also chemicaly inert, meaning it won't react under normal conditions. In the vitamin bottle, the silica acts as a dessicant, absorbing the water in the bottle to keep the vitamins dry. In my column, it acts as a stationary phase, and the hexane acts as a mobile phase. When I put my mixture onto the top of the column, and then allow more hexane to flow through the column, the parts of my mixture that are not very polar and soluble in the hexane will flow along with the hexane. Components that are more polar are less soluble in the hexane, and will tend to stay absorbed in the silica. The more hexane I pass through the column, the farther apart the components get, with the most polar ones hardly moving at all, and the least polar ones moving the farthest. The first few milliliters of hexane to emerge from the column contained all of my desired product, the second few milliliters contained the second component, but to get the third component off, I had to add a little methanol (a very polar solvent--more polar than the silica) to the column. Once I had evaporated the solvents, I had finally isolated my three compounds.


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