Measuring procedure

• Switch-on the spectrometer (see picture – step 1).
• Switch-on one of the three light emitters  - blue, green or red - of a tri-colour light emitting diode (LED) (see picture – step 2).

Set the light intensity of the selected light source  - blue, green or red -to the maximal by turning the appropriate knob to the far right position (see picture – step 3).
• Insert a blister into the measuring chamber, so that the hollow containing a blank occupies the measuring site (see picture – step 4).
• Set the transmittance to 100.0 %. Use knobs for rough and fine regulation of the transmittance (see picture – steps 5 and 6).
• Change the position of the blister in the measuring chamber, so that a calibration or examined solution occupies the measuring site (see picture – step 4).
• Read a transmittance from the display (see picture – step 7).
• Calculate absorbance from the measurement of transmittance (T) as given below:

A = - log (T/100)

Note. Within the same experiment volumes of all solutions in hollows of a blister must be equal.

Prepared by: Nataša Gros, University of Ljubljana, Faculty of Chemistry and Chemical Technology