FlashTube chromatography puts parallel purification in your own
hands. It is simple and rapid, almost like running TLC. Below are
some hints and advice when using it.
Type of compounds
All type of compounds which can be separated on silica TLC and
which absorb UV-light can be purified by FlashTube chromatography.
Finding a solvent system for elution
Usually a TLC system which separates the desired
compound(s) can be used for FlashTube chromatography. Some
examples are given below. Unlike normal chromatography relatively
high Rf-values (~0.5) can be used.
Adding the sample
The top of the column is wetted with the eluting solvent before
adding the sample. This may be dissolved in the same or sometimes
a less polar solvent. The rest of the solvent needed for the
separation is finally added. The total amounts of solvent which
can be absorbed on the columns are: FlashTube 2002: 2.5 ml. FlashTube chromatography utilizes up to
five times less solvent than normal chromatography!
Compounds which are poorly soluble in non-polar solvents may be
dissolved in small amounts of a polar solvent and added to the
column. The polar solvents are then removed under vacuum prior to
addition of the eluting solvent.
Cutting the column
When the column has been developed the desired bands are located
in UV-light and cut out with the FlashTube cutter. To avoid band
broadening this should be done relatively soon. As an alternative
to cutting out a piece of the column, the silica may be carved out
from one end of the band.
Isolating the compounds
Different procedures may be used.
Extraction/Separation. The column piece is placed in a test tube
and the plastic is removed. For extraction a relatively polar
solvent (solvent combination) is used and the silica may be
centrifuged down. Alternatively the silica is treated with a water
solution (optionally containing acid or base) and a low density
solvent added to extract the compound into the organic phase which
is finally separated.
Filtration. The column piece that has been cut out is placed in a
reservoir equipped with a filter (10µ) and a valve. The plastic
tube is removed and the silica is extracted with a relatively
polar solvent (solvent combination). The silica may alternatively
be treated with a water solution (optionally containing acid or
base) and chloroform added to extract the compound into an organic
phase which is finally separated.
FlashTubeTM Chromatography , how to use it
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