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Unformatted text preview: ry important step.
CAUTION: As stated previously, the column bed should
NEVER be allowed to dry. Remember to close the
stopcock when necessary to prevent the top of the
solvent from draining below the top of the alumina. Separation. Add approximately 10 mL of fresh
petroleum ether to the top of the column bed, open the
stopcock, and collect the eluent in a small beaker.
Monitor progress of the chromatography by
determining when the first compound starts and
finished eluting from the column. Monitoring may be
achieved by collecting a drop or two of eluent on a
watchglass after every 2-3 mL that elutes from the
column. When the solvent evaporates, any white solid
present will be visible on the watchglass. You can
determine when all of the white solid has been eluted
using this technique. Addition of more solvent may be
required (only add ~5 mL at a time). Most of the white
solid should elute with a volume of 10-20 mL of
petroleum ether, and slow movement of a yellow band
down (but not completely through) the column should
occur. Use petro...
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