Processing kodak motion picture films, module 3 analytical procedures

d. Filling
Using a bulb, draw the solution into the pipet to
a point about one inch above the calibration
mark, then remove the bulb and cap the pipes
with the forefinger.
e. Wiping Outside
Before adjusting the liquid level to the mark,
wipe off the drops adhering to the outside with a
paper cleansing tissue. This prevents droplets on
the outside from draining into the receiving
vessel and affecting the results.
f. Lowering Meniscus to Mark
Hold the pipet in a vertical position at eye level
over a waste container. Touch the tip of the pipet
against the wall of the container. Hold the waste
container at approximately a 30° angle so that
the out-flowing liquid makes continuous contact
with the container. Carefully lower the meniscus
to the mark. See Figure 5.
Figure 5 Lowering Meniscus to the Mark
F002_0908AC
Meniscus
Mark
g. Movement of Pipet to Receiving Vessel
Carefully move pipet to the receiving vessel,
avoiding rapid vertical motion which might
dispense part of the solution prior to reaching the
receiving vessel.
h. Delivery
Keeping the pipet in a vertical position, place the
tip against the wall of the receiving vessel (at
approximately a 30° angle) just above the
surface of the liquid, then remove the forefinger.
Allow to drain at a vertical position until the
continuous outflow ceases, then remove the
pipet. A small amount of the solution will, and
should, remain in the tip of the pipet. Do not
blow it out.
i. Cleaning
If, after usage, a pipet has a film of liquid in it,
not droplets of liquid, it may be reused
immediately with the same solution without
being cleaned in a cleaning solution. Merely
rinse it with the solution to be pipeted. It is not
necessary to rinse it with reagent water just prior
to rinsing with the sample to be pipeted.
However, if droplets of liquid are adhering to the
inner surface of the pipes or if it is colored, it
should be rinsed with a cleaning solution, then
rinsed inside and out with reagent water for
approximately five seconds. If drops of water
remain in the pipet, it is contaminated and must
be treated again with cleaning solution. Store
pipets in racks in a vertical position. Pipets must
be recleaned immediately before use if allowed
to stand more than an hour under ordinary
conditions of air-contamination.
3. Micropipets
Micropipets are used in methods where precise
samples, 1.00 mL or less, are required. They are
usually equipped with disposable tips. Follow the
manufacturer's instructions for care and use of the
micropipet and any additional instructions that may be
included in the method.
4 Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H24.03