Chromatotron

Rotor Set-Up for Slow Setting Layers
Masking tape in contact with a wet layer for more than about 20 min will detach
from the rotor and allow the mixture to leak out. The rotor set-up below
prevents leakage.
1 Clean and dry a
rotor. Remove from
the coating arbor and
dry the central area.
4 Push the aluminum foil up
and apply masking tape in
short (10 cm) pieces. The
tape is for stiffening only, not
for sealing.
2 Place another rotor on the
coating arbor handle, cover
with a square sheet of
aluminum foil. Press the
central area with the fingers
to mark the center hole then
pierce with the coating
arbor.
5 Press the foil and tape
together forming a neater
edge.
PARTITION CHROMATOGRAPHY, RECIPE 4
3 Place the clean rotor on
top, insert the coating arbor
and screw in. Full tightening
requires touching both rotors
(outer 5 mm only!) to allow
turning the rotors while
holding the handle. Cut the
aluminum foil to a rough
circle extending about 2 cm
beyond the rotor edge.
Partition of compounds between a moving solvent and a liquid stationary
phase retained by silica gel provides a separation method quite different from
adsorption chromatography. Partition is particularly successful for the
separation of mixtures of compounds that differ in the ratio of polar to non
polar groups, such as homologs, and for separating unrelated compounds
which by chance have the same Rf by adsorption chromatography. Only
hydrocarbon solvents give good resolution
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