Processing kodak motion picture films, module 3 analytical procedures

Spectrophotometric Determination of Total Iron in EASTMAN Color Films, “KUL” Bleach
ECN-0006/1
ECP-0006/1
Process ECN-2 ECP-2D VNF-1/LC RVNP
Formulas
SB-34/
SR-34R
SB-34/
SR-34R
INTRODUCTION
The determination of total iron in Eastman Color Films,
Process ECN-2 or Process ECP-2D, “KUL” Bleach utilizes
a spectrophotometric procedure. Total Iron is determined by
oxidizing any iron (II) present to iron (III) with persulfate. A
thiocyanate complex of the iron (III) is formed in a dilute
acid solution. A direct measurement of the iron-thiocyanate
complex is made using a calibrated spectrophotometer with
wavelength set at 477 nm. The calibration of the
spectrophotometer is described in Appendix A.
Use of 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.
PRECISION AND BIAS
Repeatability
To obtain the repeatability data, a single skilled analyst
performed five (5) replicates on each of the following
solutions during methods development:
a. A “fresh” EASTMAN Color Films, Process ECN-2 or
Process ECP-2D, “KUL” bleach prepared with all
components at their respective working tank aim
concentrations:
4.946 g/L total iron for Process ECN-2
8.728 g/L total iron for Process ECP-2D
b. A “seasoned” EASTMAN Color Films, Process ECP-2,
“KUL” bleach analyzed as received at:
5.285 g/L total iron for Process ECN-2
9.219 g/L total iron for Process ECP-2D
c. The same “seasoned” solution as in letter b, above,
analyzed after making an analytically weighed, standard
addition of:
0.529 g/L total iron for Process ECN-2
— —
1.386 g/L total iron for Process ECP-2D
Repeatability Standard Deviation, 1s r & 95 Percent
Confidence Estimate (not including bias)
Repeatability standard deviation is an estimate of the
variability one trained analyst should be able to obtain under
favorable conditions (analyzing a sample, with one
instrument, within one day).
The 95 percent confidence estimate (calculated using the
repeatability standard deviation) around a single test will
include the mean value 95 percent of the time.
Samples
(Process
ECN-2,
“KUL”
Bleach)
“Fresh” at
“Aim”
(4.946 g/L
Total Iron)
“Seasoned”,
As
Received
“Seasoned”
with
Standard
Addition
Samples
(Process
ECP-2,
“KUL”
Bleach)
“Fresh” at
“Aim”
(8.728 g/L
Total Iron)
“Seasoned”,
As
Received
“Seasoned”
with
Standard
Addition
Mean
Level
(g/L Total
Iron)
Bias
Bias is a statistically significant deviation of the mean from
the known mix level at a 95 percent confidence level. It is
determined for “fresh” samples only. Bias is not determined
for “seasoned” samples, since the component concentration
level was not determined independently of the test method.
No statistically significant bias was found for a Process
ECN-2, “KUL” “fresh” tank bleach sample.
A statistically significant low bias (–1.5 percent) was
found for a Process ECP-2, KUL “fresh” tank bleach sample.
This was judged not to be practically significant.
Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H24.03 1
(N)
Repeatability
Standard
Deviation, 1S r
(g/L Total Iron)
95 Percent
Confidence
Estimate
(g/L Total
Iron)
4.943 5 0.055 ± 0.15
5.285 5 0.12 ± 0.32
5.797 5 0.039 ± 0.11
Mean
Level
(g/L Total
Iron)
(N)
Repeatability
Standard
Deviation, 1S r
(g/L Total Iron)
95 Percent
Confidence
Estimate
(g/L Total
Iron)
8.598 5 0.046 ± 0.13
9.219 5 0.13 ± 0.36
10.610 5 0.075 ± 0.21