Processing kodak motion picture films, module 3 analytical procedures

Cerimetric Determination of Sodium Ferrocyanide in Ferricyanide Bleach
ECN-2-1101
ECP-2D-1101
ECR-1101E
Process ECN-2 ECP-2D VNF-1/LC RVNP
Formulas SR-29 SR-27 SR-40 —
PRINCIPLE
Ferrocyanide is oxidized in an acid solution by sulfato
cerate. This reaction is:
Ce +4 + Fe(CN) 6 -4 → Ce +3 + Fe(CN) 6 -3
Sodium diphenylamine sulfonate indicator is used. The
indicator has a blank of 0.1 mL sulfato cerate. This value is
used in the calculations.
This method requires handling potentially hazardous
chemicals. Consult the Material Safety Data Sheet for each
chemical before use. MSDS's are available from your
chemical supplier.
Note: Use pipets and volumetric glassware meeting the
“Class A” definition by the National Institute of Standards
and Technology (NIST).
RELIABILITY
It is difficult to see the color change of the indicator in darkcolored
seasoned samples. Thus, the resulting analyses may
vary by approximately ± 3 g/L ferrocyanide. If greater
precision is needed, refer to Method 1102, Potentiometric
Determination of Ferrocyanide in Ferricyanide Bleach and
Ferrocyanide Stock Solutions, (or the most recent revision).
REAGENTS
Use ACS Reagent Grade reagents unless specified
otherwise.
7.0 N Sulfuric Acid, H 2 SO 4
0.01 M Sodium Diphenylamine Sulfonate Indicator
0.05 N Sulfato Cerate (standardized to 4 decimal places)
PROCEDURE
Sample Treatment
1. Add approximately 500 mL of distilled water to a
1000-mL conical flask.
2. Pipet (wipe the pipet before leveling) the sample into
the flask according to the table below.
3. Add 10 mL of 7.0 N sulfuric acid from a tip-up pipet.
Titration
1. Add, with swirling, 20 drops (approximately 1 mL) of
0.01 M sodium diphenylamine sulfonate indicator.
2. Titrate immediately with standardized 0.05 N sulfato
cerate to the first scarlet color that persists for
1minute.
Calculations
10-mL sample
5-mL sample
Solution Sample Size
Fresh or regenerated Bleach 10.0 mL
Seasoned Bleach 5.0 mL
∆mL cerate = mL cerate – blank = mL cerate – 0.1
Na 4Fe(CN) 6 10H 2O, g/L =
(N cerate)(∆cerate)(eq wt Na 4Fe(CN) 6 10H 2O)(1000)
(mL sample)(1000)
(N cerate)(∆mL cerate)(484.1)(1000)
(10)(1000)
48.41(N cerate)(∆mL cerate)
(N cerate)(∆mL cerate)(484.1)(1000)
(5)(1000)
96.82(N cerate)(∆mL cerate)
Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H24.03 1
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