Extraction Technologies For Medicinal And Aromatic Plants - Unido

EXTRACTION TECHNOLOGIES FOR MEDICINAL AND AROMATIC PLANTS
Table 3: Typical column solvent volumes for column equilibration
Column size,
g
Approximate column
volume, ml
2 2.5 5
5 6.5 13
10 12.5 25
20 25 50
25 31.3 62.5
50 62.5 125
70 88 176
100 125 250
150 188 376
201
Typical solvent
volume, ml
Normal phase fl ash columns can be used without prewetting,
but some column-to-column variation may be experienced.
12.5 Sample Application
There are two popular approaches to fl ash chromatography
sample loading: wet loading and dry loading.
12.5.1 Wet Loading
Load the liquid sample directly onto the top frit of the column,
and allow it to percolate through the top of the sorbent bed. For best results,
load the sample onto a prewetted column in a non-polar solvent.
12.5.1.1 Practical Tips for Wet Loading
• Dissolve the sample in as non-polar as solvent as possible.
• If compounds are not easily soluble in a non-polar solvent,
either dissolve them in a small volume of polar solvent and
then dilute with a non-polar solvent to reduce the elution
strength, or consider dry loading of the sample (discussed
in next section).
• Position column on a FlashVac vacuum manifold equipped
with PTFE stopcock needles.
• Apply the sample evenly over the entire area of the top frit.
To do so, seal the column by closing the stopcock.
• Alternatively, load samples onto the column in on-line mode using
a Flash Master system equipped with a 3-way injection valve.