Plug in and turn on the Spec 20. It must warm up for 30 minutes before use.
Set the instrument to the proper wavelength by turning the knob located on the right hand surface of the spectrophotometer. The wavelength
setting can be seen through the window next to the knob.
Obtain a properly cleaned cuvette and fill it about 3/4 full of the reference
solution (usually water).
With no cuvette in the sample holder, close the cover and rotate the zero light control knob(left front knob) to display a reading of 0.0% transmittance. Provided that
the instrument is not turned off and this knob is not moved, no other adjustments
to this control are needed.
Place the reference solution cuvette in the sample holder, close the cover,
and rotate the light control knob (front right knob) to display a reading of 100.0% transmittance. This procedure
must be repeated every time measurements are taken at a new wavelength or
if several measurements are made at the same wavelength.