Operating Principle - palintest Photometer 7100 Manual

OPERATING PRINCIPLE

The Palintest direct-reading photometer is an instrument for measuring colour
intensity. Light is passed through a test tube containing the sample solution, and
then through a coloured filter onto a photodetector. Filters have been chosen so that
light of a specific wavelength is selected. When the solution is completely
colourless, all of the light passes through the sample. With coloured samples, light is
absorbed and that which passes through the sample is proportionately reduced.
In Palintest test procedures, the direct-reading photometer is used to measure the
colour which is produced when chemical reagents are reacted with the water
sample. In these tests, the colour intensity produced is proportional to the
concentration of the parameter under test.
The photometer is pre-programmed with calibrations for each test parameter.
Different test procedures are carried out at different wavelengths to optimize the
sensitivity of each test. The required wavelength is selected automatically by
the instrument.
The calibrations are accessed by entering a unique program number at the
start of each test procedure. This enables the instrument to select the
appropriate wavelength filter automatically and allows the photodiode
response to be converted to a concentration reading. The instrument thus
displays a direct-reading of the test result.
The photometer is ideally suited for general analytical applications. The
instrument can be used as a laboratory or field photometer for standard
analytical methods or for comparison of coloured solutions.
For general analytical applications, Transmittance (test program 0), or
Absorbance (test program 1) can be chosen.
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