Processing kodak motion picture films, module 3 analytical procedures

Instructions for Performance Checks of Ultraviolet-Visible Spectrophotometers
and Quartz Cells
ULM-0001/1
Process ECN-2 ECP-2D VNF-1/LC RVNP
Formulas All All All All
INTRODUCTION
Performance checks for ultraviolet-visible
spectrophotometers consist of a wavelength and photometric
accuracy check. The visible and ultraviolet regions are
checked for wavelength accuracy at 485.8 nm and 278.7 nm,
respectively, with a holmium oxide solution (NIST Standard
Reference Material 2034). A holmium oxide glass filter
(Corning No. 3130) can be used to check wavelength
accuracy at 453.2 nm and 279.4 nm, instead of the holmium
oxide solution. The photometric accuracy is checked in the
visible and ultraviolet region at 500 nm and 280 nm,
respectively, with a metal-on-quartz filter (NIST Standard
Reference Material 2031).
Absorption cells should only serve as a holder for the sample
and not contribute to the measured absorbance. There are
almost always differences between cells. Cells should
always be placed in the cell holder the same way and the
holder placed the same way in the instrument. Mechanical
repeatability should not contribute significant error to the
analytical procedure. The most common cause for
significant differences between absorption cells is dirty
windows. To test cleanliness, a quartz cell check is required
for spectrophotometric methods that do not involve the
measurement of a blank. The quartz cell is filled with reagent
water and an absorbance reading against air is taken at
650 nm in the visible region and 240 nm in the ultraviolet
region. The acceptable absorbance of ≤ 0.093 for each of
these wavelengths are taken from ASTM E 275-931. They
serve as useful control levels for analyses that use
precalibrated equations in the calculations.
Record all data from the performance checks on trend or
control charts.
APPARATUS
1 cm Quartz Cell
Metal-on-Quartz Filter (NIST Standard Reference
Materia 2031)
Holmium Oxide Solution in Ampouled Cell (NIST
Standard Reference Material 2034)
Holmium Oxide Glass Filter (Corning No. 3130)
REAGENTS
Water, Type I Reagent- This method uses reagent water
equivalent to or purer than Type I grade, as defined in
ASTM Standard D 1193.
Acid-Alcohol Cleaning Solution- One part 3 N
hydrochloric acid and one part 3A or isopropyl alcohol.
PROCEDURE
Preparation of Spectrophotometer
1. Follow the manufacturer's instructions for operating
the instrument, including the warm-up times for the
instrument and it’s lamps.
2. Use the appropriate lamp, as indicated:
Wavelength Range Lamp
200 - 380 nm Hydrogen or Deuterium
380 - 780 nm Tungsten
Caution
The hydrogen or deuterium lamp can produce a severe burn
on skin or to unprotected eyes. Do not look directly at the
lamp. If it is necessary to examine or adjust the lamp, use
goggles that will absorb the dangerous ultraviolet radiation.
Spectrophotometer Checks
Wavelength Check in Visible and Ultraviolet Region
Perform this procedure at least once a month, or if the
photometric accuracy check fails.
1. Check the ampouled cell containing the holmium
oxide solution for surface contamination; wipe clean
with an optical lens tissue.
2. Insert the ampouled cell into the sample holder of the
spectrophotometer after zeroing the instrument from
200 nm – 780 nm (air vs. air).
3. Scan from 200 nm – 780 nm using the wavelength
control (monochromator) in 0.5 nm increments.
4. Record the wavelengths at which the maximum
absorbance is observed near 485.8 nm and 278.7 nm.
The recorded wavelengths should be within ± 0.5 nm
of these expected values. If they are not, then contact
the instrument manufacturer.
Photometric Accuracy Check in Visible and
Ultraviolet Region
Perform this procedure at least once a day.
1. Adjust the spectrophotometer to read an absorbance of
0 at 280 nm and 500 nm (air vs. air).
2. Check the metal on quartz filter for surface
contamination; wipe clean with an optical lens tissue.
3. Place the filter in sample holder.
4. Read and record the absorbance value at 280 nm and
500 nm.
5. The absorbances at each of these wavelengths should
be within trend or control chart limits established for
the spectrophotometer. If they are not, then do a
wavelength accuracy check as described in
Wavelength Check in Visible and Ultraviolet Region.
Processing KODAK Motion Picture Films, Module 3, Analytical Procedures H24.03 1