Processing kodak motion picture films, module 3 analytical procedures

Titration of the Developing Agent with Sulfato
Cerate
Note: The end-point of the titration step can be determined
either potentiometrically (Step 1 below) or visually (Step 2
below).
1. Potentiometric Titration
a. Add 5 drops of ferroin indicator and a magnetic
stir bar to the 250-mL beaker (from steps 6 & 7
of the Back-Extraction of the Developing Agent
procedure).
Note: Do not omit the ferroin, it aids the
definition of the end point.
b. Set the following parameters, if using a
METROHM 536 titrator:
Titration mode mV/pH
Horizontal chart span 750 mV
Autocontrol OFF
Maximum titration speed 15 min/100% volume
Vertical chart span 400 mm/100% volume
Automatic titration stop
(U%)
Indicator electrode
Reference electrode
OFF
Platinum, BECKMAN,
Model 39373 or equivalent
Double-junction ORION,
Model 900200 or equivalent
c. Place the 250-mL beaker on the METROHM
titrator stand. Place the electrodes in the beaker.
(NOTE: The titrant delivery tip should be placed
so that the titrant flows past the reference
electrode before the platinum electrode.) Set the
stirrer speed to stir rapidly without splashing or
creating a vortex. Titrate the solution with
standardized 0.05 N sulfato cerate through the
inflection.
d. Determine the end point using concentric arcs.
(Refer to Universal Method ULM-0003-01,
Potentiometric Titrations for Photoprocessing
Solutions, or any subsequent revisions.) Record
the end point as mL A.
e. Add 100 mL of 1.0 N sulfuric acid to a second
250-mL beaker containing a magnetic stir bar.
Add 5 drops of ferroin indicator.
f. Place the second beaker on the METROHM
titrator stand and titrate through the inflection
point with standardized 0.05 N sulfate cerate.
Record any measurable end point as mL B.
(This is the blank. This determination needs to
be performed only once, if a series of analyses
will be performed.)
2. Visual Titration:
a. Place the 250-mL beaker (from steps 6 & 7 of
the Back-Extraction of the Developing Agent
procedure) on a magnetic stirrer. Add 5 drops of
ferroin indicator. Turn the magnetic stirrer on
and adjust the setting so that the solution stirs
vigorously but without creating a vortex or
splashing.
b. Using a 25-mL burette, titrate the solution with
standardized 0.05 N sulfato cerate to the first
green color that persists for 15 seconds. Add the
titrant dropwise when within an estimated 2 mL
of the end point, allowing sufficient time for
mixing before making another addition. Record
the end point as mL A.
c. Add 100 mL of 1.0 N sulfuric acid to a second
250-mL beaker containing a magnetic stir bar.
Add 5 drops of ferroin indicator and place the
beaker on a magnetic stirrer. Turn the magnetic
stirrer on and adjust the setting so that the
solution stirs vigorously without creating a
vortex or splashing.
d. Titrate the solution to the first light blue color
that persists for 30 seconds. Record the end point
as mL B. (This is the blank. This determination
needs to be determined only once, if a series of
analyses will be performed.)
Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H24.03 5