Processing kodak motion picture films, module 3 analytical procedures

7. Add, from a tip-up pipes, 25 mL of butyl acetate to
separatory funnel No. 2; stopper and shake the funnel
for a few seconds, then vent through the stopper.
Continue to shake vigorously for 30 seconds, venting
occasionally.
8. Allow enough time for complete separation of the
phases.
Note: It may take longer for complete separation of the
phases in highly seasoned samples.
9. Discard as completely as possible the lower (aqueous)
layer from separatory funnel No. 2 without losing any
of the top (butyl acetate) layer.
10. Transfer the contents of separatory funnel No. 2 (butyl
acetate layer) into funnel No. 1.
Back-Extraction
1. Add, from a tip-up pipes, 100 mL of 1.0 N sulfuric
acid to separatory funnel No. 2 and swirl, rinsing the
inside walls of the funnel. Save for Step 3.
2. Gently swirl separatory funnel No. 1 and discard as
completely as possible any lower (aqueous) layer that
separates, being careful not to lose any of the butyl
acetate layer.
3. Transfer the contents of separatory funnel No. 2 into
funnel No. 1.
4. Stopper separatory funnel No. 1 and shake vigorously
for 30 seconds, venting occasionally through the
stopper.
5. Allow enough time for complete separation of the
phases.
Note: It may take longer for complete separation of the
phases in highly seasoned samples.
6. Transfer the lower (acid) layer from separatory funnel
No. 1 to a 250-mL beaker without losing any of the top
layer.
7. Swirl separatory funnel No. 1 and transfer as
completely as possible any additional lower (acid)
layer that separates to the beaker.
Note: The end point of the titration can be determined
either potentiometrically or visually.
Potentiometric Titration
1. Add 5 mL 0.10 M acidified ferric nitrate to the sample.
2. Titrate the sample potentiometrically with
standardized 0.05 N sulfato cerate using an automatic
titrator with at least a 20-mL buret capacity See
Method ULM-0003-01, Potentiometric Titrations for
Photoprocessing Solutions, or any subsequent
revision.
Note: Use a one mL/min titration speed with a chart
span of approximately 1000 mV. (Appropriate settings
for individual titrators should be determined
experimentally for the best inflection point.)
3. Determine the end point by means of the concentric
arcs technique. Record this as mL A. See Method
ULM-0003-01, Potentiometric Titrations for
Photoprocessing Solutions, or any subsequent
revision.
4. Add 100 mL of 1.0 N sulfuric acid to a second 250-mL
beaker. Repeat Step 2 above. Record this as mL B.
(This is your blank and only needs to be determined
once for any batch of samples.)
5. mLA-mLB =
mL standardized 0.05 N sulfato cerate titrated
Manual (Visual) Titration
1. Stir the solution vigorously, without splashing, on a
magnetic stirrer and add 5 drops of ferroin indicator.
2. 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 two mL of the end point, allowing sufficient
time for complete mixing before making another
addition. Record the end point as mL A.
3. Add 100 mL of 1.0 N sulfuric acid to a second 250-mL
beaker with 5 drops of ferroin indicator. Repeat Step 2
above, but record the end point as the first light blue
color that persists for 15 seconds. Record this as mL B.
(This is your blank and only needs to be determined
once for any batch of samples.)
4. mLA-mLB =
mL standardized 0.05 N sulfato cerate titrated
Calculations
CD-3, g/L =
(N cerate)(mL cerate)(eq. wt. CD-3)(1000)
(mL sample)(1000)
+ 0.49
=
(N cerate)(mL cerate)(218.0)(1000)
(25.0 mL)(1000)
+ 0.49 =
8.72(N cerate)(mL cerate) + 0.49
2 Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H24.03