Processing kodak motion picture films, module 3 analytical procedures

APPARATUS
All volumetric glassware should meet all “Class A”
specifications, as defined by American Society for Testing
and Materials (ASTM) Standards E 287, E 288, and E 969,
unless otherwise stated.
Pipette, (25.0-mL)
Tip-up pipettes, (20-mL and 25-mL)
Beakers, (250-mL)
METROHM 536 Titrator or equivalent with a DOSIMAT
and a 20-mL burette
Platinum indicator electrode, BECKMAN, Model 39273
or equivalent
Double junction reference electrode, ORION Model
900200 or equivalent
Filling solutions:
ORION No. 900002 (inner chamber)
ORION No. 900003 (outer chamber)
Burette, (50-mL) / (visual method only)
Magnetic stirrer / (visual method only)
Magnetic stir bar / (visual method only)
REAGENTS
Use ACS Reagent Grade reagents unless otherwise
specified.
0.6 N potassium iodide
Zinc sulfate - 7.0 N sulfuric acid reagent
Starch indicator
Sodium thiosulfate, (Na 2 S 2 O 3 ), (0.1 N) standardized to
4 places past the decimal point
Water, Type I Reagent – This method was developed, and
the resulting statistical data were obtained using reagent
water equivalent to purer than Type I Grade, as defined in
ASTM Standard D 1193. Other grades of water, e.g.,
reverse osmosis (RO), demineralized, or distilled water,
may give equivalent results, but the effects of water
quality on method performance have not been studied.
PROCEDURE
Removal of the Interfering Constituents
1. Pipette 25.0 mL of sample into a 250-mL beaker.
2. Add 25 mL of 0.6 potassium iodide from a tip-up
pipet.
3. Add 20 mL of zinc sulfate - 7.0 N sulfuric acid reagent
from a tip-up pipet; mix thoroughly.
Titration with Sodium Thiosulfate
Note: The end-point of the titration step can be determined
either potentiometrically (Step 1) or visually (Step 2)
1. Potentiometric Titration:
a. Set the following parameters on the
METROHM Titrator:
Titration mode mV/pH
Horizontal chart
span
250 mV
Autocontrol OFF
Maximum titration
speed
15 min/100% volume
Vertical chart span 400 mm/100% volume
Automatic titration
stop (U%)
b. Place the 250-mL beaker on the METROHM
titrator stand and add a magnetic stir bar. 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 0.1 N
sodium thiosulfate through the inflection.
c. Determine the end point using concentric arcs
(Refer to method ULM-0003-01, Potentiometric
Titrations for Photoprocessing Solutions, or any
subsequent revisions.) If a microprocessor
controlled titrator is used, the endpoint will be
picked automatically.
2. Visual Titration:
a. Place the 250-mL beaker (from the Removal of
the Interfering Constituents procedure) on a
magnetic stirrer after adding a magnetic stir bar.
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 50-mL burette, titrate the solution with
standardized 0.1 N sodium thiosulfate to a light
yellow color.
c. Add 5 mL of starch indicator from a tip-up pipet,
and continue the titration until the blue color just
disappears.
4 Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H24.03
OFF
Indicator electrode Platinum, BECKMAN,
Model 39273 or equivalent
Reference electrode Double-junction ORION,
Model 900200 or equivalent