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FotoSense cannot be contaminated or poisoned
like an ion selective electrode.
It provides a very robust and cost effective sensing element for metals
determination.
The visual end-point is converted into a sharp unambiguous electronic
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Titration
Complexometric titrations of metals can be carried out
using potentiometric, thermometric or photometric sensors. Methods based on
the use of photometric sensors are generally superior and can be applied to
the vast array of documented manual titration procedures using indicator
dyes. This was the original method for complexometric titration. This
methodology provides an unobtrusive sensing technique which is extremely
robust and of general purpose.
Typical colour indicators used are murexide and
eriochrome black T and a typical complexing reagent is EDTA. The presence of
metal ion shifts the absorbance spectrum of the dye through complexing. On
titrating the sample with the chelating agent, up until the end-point, free
metal ion is present and the dye is in the metal-complex state. Thus the
characteristic colour of the dye-metal complex is observed. At and beyond
the end-point, all metal ion is complexed with the chelating agent and the
dye is in its free uncomplexed stated and displays its uncomplexed
absorbance spectrum. There is thus a sharp change of colour, which is
detected by FotoSense.
>> Examples |
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MUREXIDE
