Processing kodak motion picture films, module 3 analytical procedures

B. REPRODUCIBILITY
Customer Standard Deviation, 1sc & 95 Percent
Confidence Estimate (not including bias)
Reproducibility or customer standard deviation (1sc ) is an
estimate of the variability a customer could expect when
submitting a sample to any Photoprocessing Quality
Services laboratory, where any trained analyst could test the
sample using any instrument on any day.
The 95 percent confidence estimate (calculated using the
customer standard deviation) around a single test result will
include the mean value 95 percent of the time.
Four analysts analyzed four Accelerator tank samples, on
two different days. Duplicate analyses were performed on
each sample, on each of the two days. These samples were:
1. A “fresh” Accelerator tank solution prepared with all
components at their respective “working tank” aim
concentrations.
2. The same “fresh” solution as in number 1, above,
reanalyzed in the same manner, after making a
standard addition of 1.2038 g/L Na2S2O5 (assay
99.04 percent).
3. A “seasoned” Accelerator tank solution analyzed as
received as 2.2705 g/L Na2S2O5. 4. The same “seasoned” solution, as in number 3, above,
analyzed in the same manner, after making a standard
addition of 1.0296 g/L Na2S2O5 (assay 99.04 percent).
Sample
Mean
(g/L Na 2S 2O 5) N
Na 2 S 2 O 5
Reproducibility
Standard
Deviation, 1s c
(g/L Na 2 S 2 O 5 )
95 Percent
Confidence
Estimate
(g/L Na 2 S 2 O 5 )
“Fresh”
“Fresh” plus
2.10 16 0.115 ± 0.24
Standard
Addition
“Seasoned”,
3.17 16 0.087 ± 0.19
As
Received
“Seasoned”
2.27 16 0.111 ± 0.24
plus
Standard
Addition
3.30 15 0.128 ± 0.27
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 was not determined
for this sample because the component concentration level
was not determined independently of the test method. An
equilibrium is established between sodium metabisulfite and
PBA-1 that effectively lowers the concentration of sodium
metabisulfite in freshly mixed solutions. Therefore bias is
estimated for fresh solutions by spiking a known amount of
sodium metabisulfite to a fresh mix that has been allowed to
sit overnight, and the recovery is then calculated.
The recovery of 88.59 percent was statistically
significantly different from 100 percent 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 was 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.
The recovery of 100.05 percent was not statistically
significantly different from 100 percent at the 95 percent
confidence level.
2 Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H24.03