Development and validation of a binder-based mobile contaminant detector

Within this work, a particularly slim groundwater measuring probe with a diameter of 43 mm was developed, constructed and realised. This probe contains a conductivity probe, temperature and pressure sensors, as well as up to two measuring chambers for adsorbers in the form of small beads, which are stored in a glass bottle and flushed with fresh groundwater. The purging of the adsorber ensures that contaminants can be measured even in the lowest concentrations due to accumulation processes. At the same time, these contaminant concentrations are independent of event-related fluctuations in the concentration of the analyte. In order for the turbulence of the adsorber to cause representative results, the pumping speed of the micro gear pump in the groundwater measuring probe had to be adjusted for the used adsorber material. As an alternative to the optical evaluation, the validation of the turbulence was measured and therefore objective results was generated. For this purpose, an optical measuring chamber with three LEDs in different positions and a spectroscopic measuring probe were used to establish a validation protocol, with which the turbulence inside the glass vials was optimised for two exemplary adsorber materials. During this work, it was possible to observe various flow effects and also to determine an optimal pumping speed over the entire quantity spectrum of 0.1 to 1g Lewatit® M500 materials - this ion exchange resin in the 10 ml vials should be operated at a minimum pump speed of 20 ml/min and optimally swirled at 30 ml/min.