Processing kodak motion picture films, module 3 analytical procedures

6. Microburets
Microburets equipped with 1.00-, 5.00-, or l0.00-mL
syringes are used in some methods where
microtitrations are performed. Follow the
manufacturer's instructions for care and use of the
microburet and any additional instructions that may be
included in the method.
7. Volumetric Flasks
Volumetric flasks are generally graduated “to contain”
(TC) known volumes of solutions and should never be
used “to deliver” (TD) known volumes unless they
have been so calibrated. Volumetric flasks are used to
make up solutions to a given volume. Use Class A
flasks. See Table 1 for tolerances.
Analysts should understand and practice the following
instructions for the use of volumetric flasks.
a. Safety
Volumetric flasks are fragile, and when shaken,
should be held at both the neck and bottom. A
flask should never be shaken when held at the
neck only. When inserting a stopper, hold at the
neck rather than at the bottom.
b. Cleanliness
Use a clean flask. It usually does not have to be
dry, but it must be clean. Rinse the entire interior
of the flask two or three times with distilled
water prior to use.
c. Diluting to Volume
Add the solution to be diluted to the flask, and
add distilled water or specified diluent to bring
to volume. While raising the meniscus to the
graduation mark, hold the mark at eye level and
add the last few drops from a wash bottle or from
a small pipet. Stopper and invert 6 to 12 times to
assure homogeneity. Care should be taken when
making the initial inversion. Some solutions
have a tendency to effervesce, and loss of the
solution may result if the stopper is not held
firmly in place. If such is the characteristic of the
solution being mixed, a momentary removal of
the stopper (flask in an upright position) prior to
the second inversion will release the gas
pressure formed and avoid possible loss.
d. Cleaning and Storing
Clean the flask with Alconox or a similar
cleaning solution. It is not necessary to fill the
volumetric flask with cleaning solution. If a
generous portion is placed in the flask and the
flask is stoppered, cleaning will be
accomplished if the flask is shaken and inverted
several times so as to keep the walls moistened
with cleaning solution. After a thorough rinse
inside and out with tap water, rinse 3 times with
small quantities of reagent water. Store in an
inverted position with the bottom slightly
inclined. If the bottom is horizontal, the flask
may not drain completely.
Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H24.03 7