Water Quality
Parameters
Photometry
A photometer is used in wastewater, drinking water and environmental analysis to
determinate the concentration of dissolved substances. For this purpose,
specific reagents are added to the dissolved substance to convert it into
a measurable color. The color results from the absorption of a certain
proportion (wavelengths) of the white light, and hence the measuring is
done at the wavelength with the largest absorption.

Whithin a linear range the degree of light absorption can be translated into concentration. Thus, photometers and test sets make up a system whose components are matched optimally. Modern photometers provide method data for every test.

All necessary settings, e.g. wavelength, conversion factors, blank value (= the own color of a solution), etc. are set automatically. When calibrating user defined
methods or new reagents, the values for the test are measured, put in and stored
as a method.

The characteristics of the test sets are different for each instrument, because the
optics are different. Due to the difference in optics, it covers different measurement ranges for the same parameter measured on different photometers.