Processing kodak motion picture films, module 3 analytical procedures

Back-Extraction of CD-2
1. Add 50 mL of 1.0 N sulfuric acid to separatory funnel
No. 2 and swirl, rinsing the inside walls of the funnel.
Save the funnel contents for step 3 below.
2. Gently swirl separatory funnel No. 1 and discard as
completely as possible any lower (aqueous) layer that
separates, taking care not to lose any of the ethyl
acetate layer.
3. Transfer the contents of separatory funnel No. 2 into
funnel No. 1.
4. Swirl the funnel for 30 seconds. Stopper the funnel;
invert and vent through the stopcock. Shake the
separatory funnel horizontally for a few seconds;
invert and vent through the stopcock. Continue to
shake vigorously for 30 seconds, venting 2 times.
5. Transfer the lower (acid) layer from separatory funnel
No. 1 to a 250-mL beaker without losing any of the top
layer.
6. Swirl separatory funnel No. 1 and transfer, as
completely as possible, any additional lower (acid)
layer that separates to the beaker.
Potentiometric Titration of CD-2
1. Add 5 drops of ferroin indicator to the 250-mL beaker.
Note: Do not omit the ferroin, it aids the definition of
the end point.
2. If using a Metrohm E536 Potentiograph autotitrator,
use the following settings:
E536 Potentiograph: Control Settings
Cut-off: OFF
Autocontrol: OFF
Feeding Time: 15 min/100% volume
Selector Switch: mV, pH
Measuring Span: 750 mV
Changeover Switch: 400 mm/100% volume
Buret Size: 20 mL
Reference Electrode: Double-Junction
Indicator Electrode: Platinum Inlay/Disc
3. Place the 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.
4. Titrate the solution with standardized 0.05 N sulfato
cerate through the inflection.
5. Determine the end point using the concentric arcs
technique. (Refer to Method XIE, Potentiometric
Titrations, or any subsequent revisions.)
6. Record the end point as mL A.
7. Add 50 mL of 1.0 N sulfuric acid to a second 250-mL
beaker containing a magnetic stir bar.
8. Add 5 drops of ferroin indicator.
9. This is the blank. This determination only needs to be
performed once if a series of analyses will be
performed.
Note: This is the blank. This determination only needs
to be performed once if a series of analyses will be
performed.
Calculations
where:
CD-2, g/L =
(N cerate)(mL cerate)(eq wt CD-2)(1000)
(mL sample) x (1000)
(N cerate)(mL cerate)(107.4)(1000)
(25.0)(1000)
4.296(N cerate)(mL cerate)
mL cerate = mL A – mL B
N cerate = Normality of standardized cerate
1000 = conversion factor meq to eq in the
numerator and mL to L in the denominator
Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H24.03 3
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