The AvaSoft-CHEM module enables online concentration determination with a spectroscopy system. Lambert-Beer’s law states there is a linear relationship between absorbance and concentration:
A = e * c * l
where A is the absorbance (or extinction), e is the extinction coefficient of the compound to be measured, c is the concentration and l is the optical path length.
In practice this relation is only linear at reasonably low absorbance levels (less than 2 Au). To measure the absorbance, a few samples with known concentration are needed. It is important to always measure the absorbance at the same wavelength and using more samples of different concentrations provides a better chemometric model.
The absorbance values are used in AvaSoft-CHEM to create a linear (or second order – quadratic) calibration line. This calibration line is then used to measure the concentration of unknown samples or to measure the change in concentration over time.
AvaSoft-CHEM can display and save the calculated concentration in the following ways:
• Online display of concentration in a separate display window
• Up to eight history channel functions can be selected to display and save concentration values against time. This application can be combined with the Process-Control applications.