(4) After observing the proper waiting period, the sample color
can be measured.
The prepared (or reacted) sample is substituted for
the standardizing solution in the cell holder and the reading is taken.
The light shield lid must be closed whenever a
reading is taken.
(5) When operating the instrument on AC power, a 1-minute warm-
up period should be observed after the instrument is initially turned
When operating on battery power, the most accurate test results
will be obtained if the instrument is allowed to warm up for approxi-
mately 1 minute before standardization and then left ON only long
enough to standardize or take
of the batteries.
the reading in order to prolong the life
When operating the spectrophotometer on AC power,
caution is recommended that the instrument be
left on continually between measurements with the
wavelength dial set to 550 nm and the light con-
trol adjusted for approximately 20% transmittance.
(6) It is important that the sample cell used to standardize the
instrument be thoroughly rinsed first to ensure contaminants from the
previous test are not present.
The outside surfaces of the sample cell
should be dry when it is placed in the cell holder.
Water droplets in
the cell holder light slit, on the photocell window or on the sample
cell itself will cause error in the instrument reading.
The inside of
the cell holder should be kept clean and dry at all times.
Use extreme care when handling the filter wedge to
avoid damaging the filter surfaces or shifting the
position of the wavelength scale.
Disconnect the battery pack cable and ensure that
the AC voltage plug is connected next to the transformer on the power
circuit board (figs. 2-11 and 2-12).
(1) The spectrophotometer,
sample cells and instrument case
should be kept clean at all times and spills should be wiped up
The photocell window, located in the right-hand side of the
cell holder, can be wiped with lense tissue or a soft, lint-free cloth
which will not leave an oil film.
Sample cells can be cleaned with
soap and water or other cleaning solution.
They should be rinsed