pH – Analyzer for the pH value in water
Basis for the determination is the change of the colour of the indicator m-Cresol purple in dependence of the sample pH value. For each measurement, a small volume of indicator dye is injected into the sample stream of which the pH value is then determined by means of VIS absorption spectrometry.
Measuring the pH value using m-Cresol purple is an absolute measurement method. Combined with the technical implementation, this analyser is calibration-free and therefore suitable for long-term applications. Furthermore, the analyser can be used for monitoring of e.g. short-term biogeochemical processes.
The low reagent consumption makes long deployment times possible with only minimal maintenance requirements. Once the analyser runs out of reagents, the cartridges can be easily exchanged due to their user-friendly design. In addition, the low sample consumption enables the pH determination from small sample volumes.
Spectrophotometric pH detection - the foundation for the CONTROS HydroFIA pH
As a well proven and accepted method, the optical pH detection approach provides an accurate method that is in principle drift and calibration free being perfectly suited for long-term monitoring applications but also for use in the lab measuring discrete samples.
Impact of dissolved organic matter and hydrogen sulfide on spectrophotometric pH measurements
This study gives evidence that natural H2S concentrations have no impact on optical pH measurements, while DOM can potentially interfere. However, when using short optical path lengths as e.g. used in the CONTROS HydroFIA pH, this effect can be considered as negligible.