Bio-Rad Foresight™ Chromatography Columns, Prepacked - Manual (Page 23)

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For instance, compared to a buffer solution,
a protein solution of relatively high protein
concentration will be prone to not forming clean
single droplets on the tip of the drip director.
The droplets tend to stick to the outer surface of
the drip director, forming even bigger droplets,
which may end up in multiple wells. In contrast,
centrifugation does not have these shortcomings
and is the preferred method for sample
collection. Using a media plate with
0.8 ml well volume loaded with 0.3 ml of
liquid and equipped with a 0.45 μm filtration
membrane, a centrifugation cycle at 300 x g
for 60–120 seconds should lead to complete
sample collection. However this should be
confirmed visually, since times up to 10 minutes
are occasionally required. A swinging bucket
rotor centrifuge, equipped with a microtiter plate
bucket is recommended.
For steps such as plate equilibration, vacuum
filtration can be used. Vacuum filtration for
1 minute (or until the wells are empty) at
–1 to –3” in Hg is recommended. Visual
inspection of the wells should be conducted prior
to sample loading.
3.3.5 Mixing
An orbital shaker capable of mixing at 1100 rpm
is recommended for good mixing. The shaker
should be equipped with plate holders. The
collection and media plate should be secured
to each other and to the microtiter plate shaker
before the start of the mixing cycle. The top of
the media plate should be sealed.