Processing kodak motion picture films, module 3 analytical procedures

12. Substitute the following sample sizes in Step 8.
Sample size A std
13. Each of the standards needs to be analyzed at least
three times.
Calculation of the Absorptivity
Where:
4 mL A std #2
5 mL A std #3
10 mL A std #4
Absorptivity, L/(g-cm) =
A x DF
Assay
A = absorbance measured at 474 rnm
Assay = the value determined below
DF = the dilution factor,
Absorptivity for std. #1 =
Absorptivity for std. #2 =
Absorptivity for std. #3 =
Absorptivity for std. #4 =
(
500
100
x
)
5 sample size
3333 for std. #1
2500 for std. #2
2000 for std. #3
1000 for std. #4
3333 x A std #1
Assay
2500 x A std #2
Assay
2000 x A std #3
Assay
1000 x A std #4
Assay
A typical absorptivity is 190.0 L/(g-cm) (see APPENDIX 2,
Typical Absorptivity). Calculate a mean absorptivity using
the data from the triplicate analysis of the standards. The
mean value should have a RSD < 1.0%.
Mean =
RSD = s
A
A =
A
n
;
x 100%
Standard Deviation(s) =
(A - A)
n-1
where: A = individual absorbance measurements
n = 12
See APPENDIX 2, Typical Absorptivity for an example of
sample data.
2
Assay of 5 g/L Iron Solution
1. This assay procedure should be performed in
triplicate.
2. Pipet 25.0 mL of the stock solution of 5 g/L Fe into a
500-mL glass stoppered ERLEMMEYER flask
containing 100 mL of distilled water.
3. Add 5 mL of concentrated Hydrochloric Acid and
3 ± 0.1 g of Potassium Iodide.
4. Stopper and swirl the flask to dissolve the Potassium
Iodide. Store in a dark place for 30 minutes.
5. After the 30 minutes, remove the flask from the dark
and titrate with standardized 0.1 N Sodium
Thiosulfate (50-mL buret) from a red color to a
yellow-red color change.
6. Add 3 mL Starch indicator solution and continue
titrating until the blue to colorless endpoint persists for
15 seconds. This is mLspl .
7. Into another 500-mL ERLENMEYER flask, add
100 mL distilled water, 5 mL concentrated
Hydrochloric Acid and 3 g Potassium Iodide.
8. Stopper the flask and swirl as in Step 4. Store in the
dark for 30 minutes.
9. After 30 minutes, add 3 mL Starch indicator solution.
10. Swirl and titrate with standardized 0.1 N Sodium
Thiosulfate (50-mL beret). Titrate to the same
persistent color observed in step 6, above. This is
mLblk .
11. Each of the standards needs to be analyzed at least
three times.
Calculation of the Absorptivity
g/L Fe) =
Where:
Calculate the mean, standard deviation and RSD of the
assay. The RSD should be < 0.5%.
Where:
mL x Ew x N
25.0
Ew = Equivalent weight of Iron, 55.85
25.0 = Sample size in mL
N = Normality of the Sodium Thiosulfate
mL = mLSpl - mLblk Mean =
X =
RSD =
x 100%
Ew = the individual result
n = the number of replicates (3)
F010_0088
4 Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H24.03
s
X
n X
Standard Deviation(s) =
(X - X)
n-1
2