The Chromatotron™ centrifugal thin-layer chromatograph is now available from T-Squared Technology, Inc.
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IMPORTANT NEW RECIPE !
This new recipe replaces the former recipe no. 1 that was based on silica gel PF (Merck 7749).
There is now no requirement to protect layers from drafts during
drying. The new layers can be dried by any of several methods: 1.Exposure to the air with or without a fan. 2.Heating with a 60 watt lamp above the
rotor. 3.Oven drying at temperatures not higher than 50°C.
Recipe 1, Silica Gel TLC Standard Grade - Gypsum
| Layer thickness |
1 mm |
2 mm |
4 mm |
8 mm |
| Silica gel, TLC standard grade |
33g |
45g |
75g |
137g |
| Calcium sulfate hemihydrate |
13g |
18g |
30g |
55g |
| Water at 0-10°C |
82 ml |
112 ml |
187 ml |
343 ml |
Silica gel TLC standard grade (contains 254 nm fluorescent indicator)
is Sigma - Aldrich item no. 288586. Calcium sulfate hemihydrate (plaster
of Paris, dried gypsum) is available from various chemical suppliers
but material from hardware stores is usually of better quality.
Cover the layer and allow to set for at least 1 hr (overnight OK) before drying.
Suggested Mixing Jar Sizes
| Layer thickness |
1 mm |
2 mm |
4 mm |
8 mm |
| Mixing jar size |
250-400 ml |
300-400 ml |
400-600 ml |
750-1100 ml |
For easy mixing, the jar should be not more than 70% full with the dry sorbent.
Check the quality of the calcium sulfate hemihydrate: With a spatula
stir a 5g sample and 5 ml of water in a 25 ml beaker then mix
continuously by swirling. The mix should thicken after about 7 -14 min
to the point where it will not move when tilted. Thickening outside of this time interval, indicates the presence of impurities, usually calcium
sulfate dihydrate, that will make rotor coating difficult. If sorbent layers crack, try another source or brand of plaster of Paris.
The TLC standard grade silica gel has a reduced porosity. Reduce the solvent flow rates: a funnel should be at 55cm (bench to stopcock). Pumps should be used at the lower end of the recommended flow rates.
© Harrison Research 2014
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