Hints, Tips, and Tricks for Using the Spectronic
20.
1.
The analog instruments work just as well as the digital, and in some
cases are better.
2.
If you use the analog instrument, when the directions say to read
the %Transmittance, read it from the TOP scale. When
the directions say to read the Absorption, read it from the BOTTOM scale.
3.
When using the analog instrument, line up the needle, the needleÕs
reflection in the mirror, and your eyes. This
eliminates errors from reading the scale sideways. See
diagram below.
4.
It is not necessary to fill the cuvettes all the way to the top. They should only be 80 to 90% full.
5.
Make sure the all cuvettes are clean, inside and out. Dirty cuvettes will have air bubbles in them. In almost all cases of instrument error at low concentrations,
the source of the problem was air bubbles in the blank or sample.
6.
When finished, turn off the power (left hand knob fully counterclockwise)
and remove the cuvette from the instrument.
For a detailed discussion
of Parallax Error, please see: