Processing kodak motion picture films, module 3 analytical procedures

Titrimetric Determination of EASTMAN Color Developing Agent, CD-3, in Process ECN-2
Developer with Sulfato Cerate
ECN-0003/1
Process ECN-2 ECP-2B VNF-1/LC RVNP
Formulas SD-49 — — —
INTRODUCTION
This method describes an analytical procedure for measuring
EASTMAN Color Developing Agent, CD-3, in Process
ECN-2 Developer. CD-3 in the aqueous developer sample is
extracted with an organic solvent (butyl acetate). An
inorganic salt (NaCI) and a surfactant (polystyrene
sulfonate) are added to minimize the formation of emulsion
layers during the extraction of CD-3. In seasoned samples,
an emulsion layer is usually present. If the layer does not
transfer to the sulfuric acid, no significant error is
introduced. The CD-3 in the solvent layer is then backextracted
with sulfuric acid. This acid layer can then be
titrated with sulfato cerate, using either an automatic titrator
to record a potentiometric end point or manually titrated
using ferroin indicator, to detect the end point visually.
The potentiometric titration is recommended over the
visual end point titration. However, for those unable to use
instrumentation, the manual titrimetric technique, using the
visual ferroin indicator, is included. Judging end points with
a visual color change, especially if the samples are highly
seasoned and highly colored, can differ from person to
person. The potentiometric method overcomes this problem
because the end point is detected potentiometrically and
displayed graphically by the titrator.
For the potentiometric measurement, a METROHM
Potentiograph, Model E536 or equivalent should be used.
The potentiometric titration requires a platinum indicator
electrode and a double-junction reference electrode.
This method requires handling potentially hazardous
chemicals. Consult the Material Safety Data Sheet for each
chemical before use. MSDS's are available from your
chemical supplier.
PRECISION AND BIAS
Repeatability
To obtain the repeatability data, a single skilled analyst
performed five (5) replicates on each of the following
solutions during methods development (this procedure was
performed by both potentiometric and visual end point
detection):
a. A “fresh” EASTMAN Color Films, Process ECN-2
developer prepared with all components at their
respective working tank aim concentrations
(4.0023 g/L CD-3).
b. A “seasoned” EASTMAN Color Films, Process ECN-2
developer analyzed as received at 2.755 g/L CD-3
(potentiometrically) and 2.250 g/L CD-3 (visually).
c. The same “seasoned” solution as in number b, above,
reanalyzed after making an analytically weighed,
standard addition of 1.354 g/L CD-3 for the
potentiometric study and 1.117 g/L CD-3 for the visual
study.
Reproducibility
(Customer Standard Deviation, 1sc )
Three EASTMAN Color Films, Process ECN-2 developer
samples were analyzed by four trained analysts, each using
different titration stations, on two different days. Each
analyst analyzed each sample by both the potentiometric and
the visual end point technique. Duplicate analyses were
performed on each sample, on each of the two days. These
samples were:
a. A “fresh” tank solution prepared at 4.008 g/L CD-3.
b. An EASTMAN Color Films, Process ECN-2
“seasoned” tank developer sample analyzed, as
received, in the same manner as the “fresh” developer.
c. The same (as in #b, above) EASTMAN Color Films,
Process ECN-2 “seasoned” tank developer sample
reanalyzed in the same manner as the “fresh” developer,
after a standard addition of CD-3 was made. The
“seasoned” sample of EASTMAN Color Films, Process
ECN-2 developer, analyzed to be 3.7067 g/L CD-3
(potentiometrically) and 3.7270 g/L CD-3 (visually). A
standard addition of 1.130 g/L CD-3 was made to that
“seasoned” sample for the potentiometric and visual
calibration study.
Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H24.03 1