Processing kodak motion picture films, module 3 analytical procedures

PROCEDURE
A. Sample Treatment
1. Pipet 10.0 mL of sample into a l00-mL volumetric
flask containing approximately 50 mL of reagent
water.
2. Bring to volume with reagent water and invert the
flask 6 to 9 times to mix.
3. Pipet 10.0 mL from the l00-mL volumetric flask into a
250-mL beaker containing 100 mL of reagent water
and a magnetic stir bar.
4. Add 10 mL of 7.0 N sulfuric acid from a tip-up pipet.
Place the beaker on a magnetic stirrer. Turn on the
stirrer.
B. Titration
1. Set the following parameters on the METROHM
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%) OFF
Indicator electrode Silver/Sulfide Ion
Selective, Orion
Model 941600 or
equivalent
Reference electrode Double-Junction, Orion
Model 900200 or
equivalent
2. 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 silver/silver electrode.) Set the
stirrer speed to stir rapidly without splashing or
creating a vortex. Titrate the solution with
standardized 0.05 N silver nitrate through the
inflection.
3. 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.
CALCULATIONS
For NH 4 Br;
g/L NH 4 Br = (mL AgNO 3) (N AgNO 3) (eq wt NH 4Br) (10) (1000)
(mL sample)(1000)
Where
mL AgNO3 = volume of AgNO3 in millilitres required to
reach the equivalence point
N = normality of the AgNO3 in milliequivalents per
millilitre (meq/mL)
eq wt = equivalent weight of ammonium bromide in
milligrams per milliequivalent (97.9 mg/meq)
10 = dilution factor for sample
mL sample = millilitres of sample pipetted in step 1 of part A
of procedure
1000 = factor to convert meq to eq in the numerator
and mL to L in the denominator
If mL 0.0492 N AgNO 3 = 10.34 mLs:
(10.34) (0.0492) (97.9) (10) (1000)
g/L NH4Br =
(10.00) (1000)
= 49.8 g/L NH4Br Figure 2 S-shaped Curves
Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H24.03 3
+150
0
−150
+ MiliVolts
−
−300
6 MiliLiters
5
4
3
2
1
F002_1123GC