Processing kodak motion picture films, module 3 analytical procedures

95 Percent Confidence Estimate (not including bias)
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. It is not
adjusted for the method bias.
Sample
Fresh
(prepared at 6.003 g/L NaSCN
as 100% salt)
Seasoned
(mean = 5.97 g/L NaSCN
as 100% salt)
APPARATUS
All volumetric glassware should meet all “Class A”
specifications, as defined by American Society for Testing
and Materials (ASTM) Standards E 287, E 288, and E 969,
unless otherwise stated.
1-cm silica cells
Spectrophotometer, equipped with a visible light source
(i.e., SHIMADZU Model UV 160 U or equivalent)
5, 10-mL pipets
100, 250-mL volumetric flasks
95 Percent
Confidence Estimate
± 0.12 g/L NaSCN
as 100% salt
± 0.10 g/L NaSCN
as 100% salt
REAGENTS
Use ACS Reagent Grade reagents unless otherwise
specified.
0.10 M Acidified Ferric Nitrate
Warning
Acidified ferric nitrate is very corrosive to eyes, skin, and
metals.
Water, Type I Reagent—This method was developed
using reagent water equivalent to purer than Type I Grade,
as defined in ASTM Standard D 1193. Other grades of
water, e.g., reverse osmosis (RO), demineralized, or
distilled water, may give equivalent results, but the effects
of water quality on method performance have not been
studied.
PROCEDURE
1. Pipet 10.0 mL of sample into a 100-mL volumetric
flask. Dilute to volume with reagent water and mix
thoroughly.
2. Set a timer for two minutes, but do not start.
3. Pipet 5.0 mL of the solution from step 1 into a 250-mL
volumetric flask. Dilute to volume with 0.10 M
acidified ferric nitrate and mix thoroughly.
4. Start timer and allow the solution to sand for two
minutes.
5. Set the spectrophotometer wavelength to 460 nm. Fill
two clean 1-cm silica cells with 0.10 M acidified ferric
nitrate. Place one cell in the sample beam, and the
other in the reference beam. Either adjust the balance
(zero control) until the spectrophotometer reads 0.000
absorbance or use the instrument autozero, if so
equipped.
6. After two minutes has elapsed, rinse the cell from the
sample beam several times and fill with the solution
from step 3. Rinse the outer faces of the cell with
reagent water and carefully dry with a tissue.
Determine the absorbance at 460 nm vs the 0.10 M
acidified ferric nitrate blank.
CALCULATIONS
y = mx + b
Definition of the equation is found in the Regression section
of Appendix A:
NaSCN, g/L as 100% salt = m(ABS) + b
Where:
m = slope of the calibration line
(g/L NaSCN/ABU @ 460 nm)
ABS = Absorbance of sample vs 0.10 acidified ferric nitrate
blank
b = the intercept of the calibration line with the y-axis
(g/L NaSCN)
Each laboratory should establish its own regression equation
based on a set of calibration standards. APPENDIX A
explains this calibration procedure. The regression equation
may be different for each spectrophotometer. A typical
regression equation line for the developer is described by the
following equation:
NaSCN, g/L as 100% salt = 9.65 (ABS) – 0.07
Example Calculation
NaSCN, g/L as 100% salt = 9.65 (0.630) – 0.07
= 6.01 g/L NaSCN
2 Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H24.03