Processing kodak motion picture films, module 3 analytical procedures

Determination of Total Iron in EASTMAN Color Films, Process ECN-2 “UL” Type Bleach
Using a HACH Pocket Colorimeter Test Kit
ECN-0026-01
INTRODUCTION
This test kit (HACH catalog no. 46700-22) is used to
determine total iron in Eastman Color Films,
Process ECN-2, “UL” type bleach samples. The bleach
samples are diluted and mixed with a FerroVer® Iron
Reagent Powder Pillow to create a colored solution. This
colored solution is measured using the HACH Pocket
Colorimeter provided with the test kit. The absorbance is
then used to calculate the amount of iron in the bleach.
“Determination of Total Iron in Eastman Color Films,
Process ECN-2, UL Type Bleach Using HACH Colorimeter
Test Kit” (ECN-2-UL-3280) is used with the previous analog
colorimeter Model DR 100.
Use of this method requires handling of potentially
hazardous chemicals. Material Safety Data Sheets (MSDS)
should be consulted for each chemical before use. These can
be obtained from each chemical supplier.
PRECISION AND BIAS
Repeatability Standard Deviation (1sr) ) &
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.
To obtain the repeatability data, a single skilled analyst
performed five (5) replicates on each of the following
solutions during methods development.
1. A “fresh” UL type bleach tank prepared with all
components at their respective “working tank” aim
concentrations.
2. A “seasoned” UL type bleach tank analyzed
colorimetrically as received, at 5.59 g/L iron.
3. The same “seasoned” solution as in number 2, above,
reanalyzed after making an analytically weighed,
standard addition of 1.68 g/L iron.
Sample
“Fresh”
(Prepared
at 4.94 g/L)
“Seasoned”
As Received
“Seasoned”
plus
Standard
Addition
Mean
(g/L 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
is not determined independently of the test method.
A bias of 0.10 g/L iron was found to be statistically
significant at the 95 percent confidence level, but was judged
not to be practically significant.
Recovery
Recovery is used for seasoned samples, since the component
concentration level is not determined independently of the
test method. It is defined as the calculated mean for the
seasoned sample with a standard addition of the component
minus the mean for the seasoned sample, divided by the
actual amount of the standard addition. It is expressed as a
percentage.
Statistically, the recovery of 87.50 percent was
statistically different from 100 percent at the 95 percent
confidence level, but was judged not to be practically
significant.
Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H24.03 1
Iron
N
Repeatability
Standard
Deviation, 1S r
(g/L Iron)
95 Percent
Confidence
Estimate
(g/L Iron)
5.04 5 0.065 ± 0.18
5.59 5 0.022 ± 0.06
7.06 5 0.065 ± 0.18