Processing kodak motion picture films, module 3 analytical procedures

The Selection, Care, and Use of Volumetric Glassware and Weighing Equipment
ULM-0005/1
Introduction
This document outlines the various glassware and weighing
equipment required to accurately perform the procedures for
analyzing photoprocessing chemistry defined in methods.
Most require measurement of liquids with a tolerance of
± 0.1 mLs and weights of 0.001 g.
VOLUMETRIC MEASURING EQUIPMENT
The standard unit of volume in the metric system is the litre.
It is defined as the volume occupied by the mass of one
kilogram of water at its temperature of maximum density
and under normal atmospheric pressure. Volumetric
glassware is calibrated in terms of litres (L) or
millilitres (mL). A volumetric determination can be no better
than the equipment and technique used in performing it.
Table 1 at the end of this document summarizes the various
glassware and gives information on the specifications of
each type.
Selection And Tolerances
The volumetric glassware used must have adequate accuracy
to avoid introducing a significant error to the analytical
result. If a volume of solution is critical in an analytical
procedure, pipets, burets, or volumetric flasks of high
accuracy must be used. Other steps may require the
measurement of only an approximate volume, thus either a
graduated cylinder or a “tip-up pipet” may be used.
The National Institute of Standards and Technology
(formerly National Bureau of Standards) Circular 602
specifies tolerances for volumetric glassware that meet the
most precise requirements of the analytical procedures used
in the control of photographic processing. This equipment is
designated in Federal Specification DD-V-581 as “Class A.”
Glassware certified to meet these specifications are available
from most manufacturers of laboratory glassware. The
required tolerances are given in Table 1.
Care of Volumetric Glassware
1. Cleaning Solutions
A piece of glass apparatus is not sufficiently clean
unless its surface is uniformly wetted by reagent
water *. Grease prevents the glass walls from being
uniformly wetted, causing drainage to be uneven and
delivery not precise. To keep volumetric glassware
scrupulously clean and free from grease, three types of
cleaning solutions are recommended. These solutions
are used undiluted and may be re-used until no longer
effective. Do not draw any of these cleaning solutions
into pipets or burets by mouth. Use a rubber bulb.
* Water, Type I Reagent - Reagent water equivalent to or 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.
a. Types
Detergent—Most detergents are very effective
for most cleaning problems encountered.
Sulfuric Dichromate—A solution of sodium or
potassium dichromate in concentrated sulfuric
acid (H2SO4 ) is most effective against grease. It
is also the most dangerous because of its strong
acid, oxidizing, and dehydrating properties. Add
about 30 grams of sodium dichromate to one
litre of concentrated sulfuric acid. Technical
grade dichromate and acid are satisfactory, and
the exact concentration of sodium dichromate is
not important. After stirring the mixture a few
minutes, decant the clear liquid from any
sediment that may clog buret or pipet tips during
cleaning. The solution will become green as it
loses its usefulness as an oxidizing and cleansing
agent and should be discarded.
Acid-Alcohol—A solution of one volume of
3 N hydrochloric acid (HCl) added to one
volume of practical or reagent-grade methyl
alcohol is effective in removing cyan stains and
in cleaning spectrophotometer cells.
Caution
Do not mix this solution in a closed container.
The heat produced may cause a dangerous
increase in pressure.
b. Safety
When mixing and handling the sulfuric
dichromate or acid-alcohol cleaning solutions,
wear rubber gloves and safety goggles and
observe the other safety precautions for handling
concentrated acids. Never add water to sulfuricdichromate
solution in a container because
excessive heat and steam are likely to spatter the
hot acid. If acid is spilled on the skin or clothing
or splashed into the eyes, flush the affected parts
with a large amount of water. The water will
dilute the acid and wash it away. Seek medical
treatment immediately.
2. Cleaning and Storing Glassware
To use a cleaning solution, the glassware should first
be rinsed well with water, then immersed in or filled
with the cleaning solution for a few minutes. The
cleaning solutions are best stored and used in
polyethylene containers. Pipet jars, being tubular, are
excellent for soaking and storing pipets and burets.
After treatment with a cleaning solution, the glassware
should be thoroughly rinsed inside and out with
reagent water. For reasons of economy, ordinary tap
water may be used for the preliminary rinsing,
reserving the reagent water for the final rinsing. If
Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H24.03 1