D:\219544656.doc
Spec-20
Directions for Operations
Sample holder (cuvettes only)
Wavelength Adjustment
Zero
Transmittance
Adjustment
100 %
Transmittance
Adjustment
1. Pick wave length using the wave length adjustment knob.
2. With no cuvette in the sample holder sent instrument to zero transmittance (left knob).
3. With distilled water blank in a cuvette in the cuvette holder, or the blank requested in the
experiment, set the transmittance to 100% using the Transmittance Adjustment knob.
4. Switch Mode to Absorbance
5. Fill cuvette 3/4 full with the solution to be analyzed and record absorbance.
6. Whenever the wavelength is changed, the instrument needs to be re-zeroed and re-blanked.
(transmittance set to zero using the required blank.)
7. Be sure to wipe cuvette with Kim-Wipe before placing the cuvette in the sample holder and
make sure the line on the cuvette lines up with the raised plastic line on the top of the sample
holder.
8. To determine the wavelength of maximum absorption set the wave length to 440nm. Measure
the absorbance from 440nm to 700nm, taking readings at 20 nm intervals. In the region of
maximum absorbance, take readings at intervals of 5 nm. A smooth curve of the data is
required to determine the wavelength of maximum absorbance.