Terms in this set (79)

Preparing:
CHAMBER:
-add 3-4 mm of solvent to a beaker (TLC chamber)
-take filter paper (cut so that it does not stick out over beaker) and put into beaker
-cap chamber and let solvent (mobile phase, developing solvent) equilibrate
-filter paper takes mobile phase and helps transition to vapor phase
PLATE:
-draw 1 cm line on bottom with pencil
-take capillary tube and dip in solution
-press capillary tube against TLC plate lightly and quickly

1. Injection - load sample onto instrument/column/TLC plate
-TLC: spotting
-take capillary tube and dip in solution with mixture -> press against TLC plate lightly and quickly
-compound should be in dilute solution
2. Separation - run solvent through instrument/column/TLC plate
-TLC: developing TLC plate
3. Detection - determine results of the chromatography
-TLC: visualization (fluorescence, staining)

-solid phase (silica, alumina, cellulose) is polar
-polar compounds bind stronger to solid phase = MOVE SLOWER
-nonpolar compounds can bind only by weak Van der Waals forces = MOVE FASTER
-smaller particles (or longer TLC plate) = more theoretical plates
-solvent also affects distance traveled
-compounds move slower in nonpolar SOLVENTS

COMMON SOLVENT SYSTEMS
-you do not have to use a pure solvent, you can use a mixture to cater to the polarity you want
-hexanes (nonpolar)
-DCM (nonpolar)
-ether (moderately polar)
-ethyl acetate (moderately polar)
-acetone (polar)
-water not advised b/c it dissolves silica gel
-most common system is a ratio of hexanes/ethyl acetate
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