additions of 34.57 g/L thiosulfate ion and 5.444 g/L sodium sulfite were made to that “seasoned” sample.

POTENTIOMETRIC TITRATION STATISTICS

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.

HYPO INDEX (1 mL)

Samples

Mean Level

 

Repeatability

95 Percent

(N)

Standard Deviation, 1Sr

Confidence Estimate

(Process ECN-2 Fixer)

(mL 0.1 N I2)

 

(mL 0.1 N I2)

(mL 0.1 N I2)

 

 

 

“Fresh” at “Aim”

10.02

5

0.086

±

0.24

 

 

 

 

 

 

“Seasoned”, As

15.80

5

0.073

±

0.20

Received

 

 

 

 

 

 

 

 

 

 

 

“Seasoned” with

19.38

5

0.14

±

0.39

Standard Addition

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

THIOSULFATE

 

 

 

 

 

 

 

Samples

Mean Level

 

Repeatability

95 Percent

(N)

Standard Deviation, 1Sr

Confidence Estimate

(Process ECN-2 Fixer)

=

(g/L S2O3 )

 

=

 

=

 

 

 

(g/L S2O3 )

(g/L S2O3 )

“Fresh” at “Aim”

81.18

5

0.67

±

1.9

 

 

 

 

 

 

“Seasoned”, As

125.67

5

0.47

±

1.3

Received

 

 

 

 

 

 

 

 

 

 

 

“Seasoned” with

153.79

5

0.60

±

1.7

Standard Addition

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SULFITE

 

 

 

 

 

 

 

Samples

Mean Level

 

Repeatability

95 Percent

(N)

Standard Deviation, 1Sr

Confidence Estimate

(Process ECN-2 Fixer)

(g/L Na2SO3)

 

(g/L Na2SO3)

(g/L Na2SO3)

 

 

 

“Fresh” at “Aim”

17.55

5

0.69

±

1.9

 

 

 

 

 

 

“Seasoned”, As

28.92

5

0.65

±

1.8

Received

 

 

 

 

 

 

 

 

 

 

 

“Seasoned” with

35.69

5

1.18

±

3.3

Standard Addition

 

 

 

 

 

 

 

 

 

 

 

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.

A statistically significant bias for thiosulfate of

(-1.09 percent) was found for a “fresh” tank Process ECN-2 Fixer sample. The biases for Hypo Index and Sodium Sulfite were not statistically significant. However, the bias for thiosulfate was judged not to be practically significant.

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Processing KODAK Motion Picture Films, Module 3, Analytical Procedures • H24.03

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Kodak ECN-0002/1 manual Potentiometric Titration Statistics, Bias, Thiosulfate, Sulfite