ES-O₃-M

• Calibrated, easy to use and maintain
• Fast response (<4.5 seconds), dissolved O₃ microsensor
• Inbuilt temperature compensation measurements
• Direct measurements of dissolved O₃ for wastewater monitoring and scientific research
• Extremely stable signal for accurate and reliable measurements
• Portable meter or online, continuous monitoring options

The microprocessor-operated measuring instrument has been developed for the fast and accurate in-situ determination of dissolved ozone without any sampling.

The instrument is useful for the laboratory and for simple and fast measurements in the field (e.g., swimming pools, drinking water, chemical industry). It is equipped with an amperometric, membrane-covered O3 Microsensor that does not have to be streamed and with a temperature sensor. The display shows the concentration of the measured dissolved ozone in mg/l and the temperature of the sample.

The measuring instrument is powered via the included power supply unit and can also be operated with batteries. The RS232 interface allows the instrument to be linked to a PC or notebook.

By exchanging the O₃-sensor tip against a galvanic oxygen micro-sensor tip, the measuring instrument could be changed fast and simply into a high-performance oxygen measuring instrument. Furthermore, the instrument is useful to store the calibration coefficients of up to 10 different chemical micro-sensors and calculate the concentration units using the measured raw data. This also allows the fast and simple exchange of sensors and measuring ranges if required.

the ES-O₃-M advantage

Compared with the other commercially available so-called macro-sensors and compared with the other available high-tech and very expensive instruments (especially optical instruments), the new measuring instrument with amperometric micro-sensor has the following advantages:

1. No streaming of the sensor’s membrane is necessary; very low analyte consumption
2. No exchange of membrane or electrolyte for maintenance
3. Very fast response time of the sensor (some seconds for t90%)
4. Analysis without any sampling or adding of chemicals
5. Very low detection limit: down to 0,02 mg/l
6. High accuracy
7. High economic efficiency (no chemical consumption)
8. Measurements are also possible in turbid, coloured, muddy and salt-containing samples
9. Continuous online measurements (not only average measurements of a big volume)
10. High local resolution of the measurements (μm-steps)
11. Immediate display of the ozone concentration (mg/l)

the working principle of the O₃ sensor

Because of the partial pressure of gaseous ozone dissolved in the sample, the analyte is separated by permeation through the membrane. The membrane is only suitable for gases, so liquids, ions, and solids cannot reach the inner electrolyte of the sensor.

The sensor contains an electrolyte with a redox catalyst (= redox mediator) and 3 electrodes. The electrode materials have been carefully chosen and prepared to realize ideal electrochemical conditions.

At the electrodes, a special polarization voltage is adjusted to realize a well-defined concentration ratio of the redox catalyst's oxidized and reduced form. The time for the polarization, realized by means of the sensors integrated electronic device, is approximately 5-10 minutes. If the ozone now passes the membrane, it reacts first chemically with the redox catalyst to form a reaction product, followed by the electrochemical reduction of the reaction product at the working electrode. Caused by the polarization voltage, the system is now endeavouring to adjust the former concentration ratio. This causes a current similar to the dissolved ozone amount of the sample. Besides, the current flow in the amperometric sensor leads to a rapid decrease of the analyte inside the sensor, resulting in very fast response times if a rapid change from high to very low concentration levels is necessary.

All electrochemically working sensors must be combined with a temperature measurement and the amperometric ozone sensor. When ordering a multisensor measuring system for laboratory use or a complete submersible probe system, the temperature measurement and the temperature correction of the sensor signal are already included.

If measurements in a flow-through system are required, special temperature sensors for the integration in AMT flow-through cells are offered. When measuring in opened vessels or beakers in the laboratory, the customers have to realize the temperature measurement themselves.

If a calibrated sensor is ordered, temperature correction is very easy using a factor or, for more accurate measurements, a mathematical formula delivered with the sensor.