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Processing KODAK Motion Picture Films, Module 3, Analytical Procedures 3
Recovery
Recovery is used instead of bias 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 table below
shows whether or not a recovery is statistically or practically different
from 100 percent.
Reliability
Customer Standard Deviation, 1s
c
& 95 Percent
Confidence Estimate (not including bias)
The customer standard deviation 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.
POTENTIOMETRIC RECOVERY, Process ECN-2
Analyte Recovery Value Statistically Significant Practically Significant
Hypo Index (1 mL) 76% Yes No
Thiosulfate (S
2
O
3
=
)74% Yes No
Sodium Sulfite (Na
2
SO
3
) 80.4% No No
HYPO INDEX
Samples (Process
ECN-2 Fixer)
Mean Level
(mL 0.1 N I
2
)
(N)
Reproducibility
Standard Deviation, 1S
c
(mL 0.1 N I
2
)
95 Percent
Confidence Estimate
(mL 0.1 N I
2
)
“Fresh” at “Aim” 12.88 16 0.25 ± 0.54
“Seasoned”, As
Received
12.73 16 0.13 ± 0.27
“Seasoned” with
Standard Addition
15.83 16 0.16 ± 0.33
THIOSULFATE
Samples (Process
ECN-2 Fixer)
Mean Level
(g/L S
2
O
3
=
)
(N)
Reproducibility
Standard Deviation, 1S
c
(g/L S
2
O
3
=
)
95 Percent
Confidence Estimate
(g/L S
2
O
3
=
)
“Fresh” at “Aim” 108.14 16 0.94 ± 2.00
“Seasoned”, As
Received
114.86 16 0.73 ± 1.56
“Seasoned” with
Standard Addition
142.23 16 0.78 ± 1.67
SULFITE (Na
2
SO
3
)
Samples (Process
ECN-2 Fixer)
Mean Level
(g/L Na
2
SO
3
)
(N)
Reproducibility
Standard Deviation, 1S
c
(g/L Na
2
SO
3
)
95 Percent
Confidence Estimate
(g/L Na
2
SO
3
)
“Fresh” at “Aim” 20.79 15 0.59 ± 1.26
“Seasoned”, As
Received
15.70 16 0.68 ± 1.45
“Seasoned” with
Standard Addition
19.85 16 0.76 ± 1.63