18
5
Sample Processing - Membrane Filtration
12
When all of the sample has been filtered,
detach the vacuum pump and remove
the filter funnel from the rubber base.
The membrane filter is now ready to
be removed and placed in the petri
dish containing the absorbent pad and
growth media.
13
Remove one of the sterile petri dishes
previously prepared from the rack and place
onto the work-surface. (Prepared petri
dishes should contain an absorbent pad,
if not, follow the procedure in Section 3.3).
14
Taking care to only handle the petri dish
by the sides, remove the lid and place it
on the work surface.
15
Take an MMD containing liquid MLSB
media. Shake well then remove the blue
screw lid and place it, lid-down, onto
the work-surface.
16
Lift the petri dish containing the
absorbent pad and hold between
thumb and forefinger.
17
Take the MMD containing the liquid
MLSB and carefully pour the media onto
the absorbent pad in the petri dish in a
single, decisive pouring motion. Always
ensure that the petri dish is raised from
the surface when pouring the media.
Never use the plastic Pasteur pipettes
to dispense media onto the pads.
18
Ensure the pad is well saturated with a
small excess of MLSB visible at the edges.
This should equate to between 2.5 and
3.0mls. If too much media is dispensed,
simply pour the excess away. Place the
petri dish back down on the work surface.
