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Processing KODAK Motion Picture Films, Module 3, Analytical Procedures 5
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
show whether or not a recovery is statistically or practically
significant from 100 percent.
Customer Standard Deviation, 1s
c
& 95 Percent
Confidence Estimate (not including bias)
The customer standard deviation (1s
c
) 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.
VISUAL RECOVERY, Process ECN-2
Analyte Recovery Value Statistically Significant Practically Significant
Hypo Index (1 mL) 73.3% Yes No
Thiosulfate (S
2
O
3
=
) 80.4% Yes No
Sodium Sulfite (Na
2
SO
3
) 53.4% Yes No
HYPO INDEX (1.0 mL)
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” 12.97 16 0.18 ± 0.39
“Seasoned”, As
Received
12.70 16 0.15 ± 0.31
“Seasoned” with
Standard Addition
15.93 16 0.20 ± 0.43
THIOSULFATE (S
2
O
3
=
)
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” 107.95 16 0.93 ± 1.99
“Seasoned”, As
Received
114.95 16 0.97 ± 2.06
“Seasoned” with
Standard Addition
142.59 16 1.07 ± 2.28
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” 21.17 16 1.18 ± 2.52
“Seasoned”, As
Received
15.46 16 1.14 ± 2.43
“Seasoned” with
Standard Addition
20.23 16 1.58 ± 3.38