Tough pH Application? Consider The ProCon P14 Series

Chlorides and sulfur-based substances can create reference poisoning, which can have a major influence on pH sensors. When contaminants in the sample, such as chlorides or sulfur-based compounds, react with the reference electrode and alter its voltage, reference poisoning occurs. This can cause the sensor to provide erroneous results or possibly cause the sensor to fail.

Typically, a pH sensor’s reference electrode is composed of a metal, such as silver or silver chloride, that is in contact with a solution of known pH. This solution, known as the reference electrolyte, provides the sensor with a constant voltage for measuring the pH of the sample. A porous glass or ceramic junction connects the reference electrode to the sensor, allowing ions to pass between the reference electrolyte and the sample.

When chlorides or sulfur-containing compounds are present in a sample, they can react with the reference electrode and alter its voltage. As an example, chlorides can react with the silver in the reference electrode to generate silver chloride, which can alter the reference electrode’s voltage. Similarly, sulfur-based compounds can alter the voltage of the reference electrode by reacting with it. These processes can lead the reference electrode to generate erroneous voltages, which in turn can cause the sensor to generate erroneous pH values.

Reference poisoning can be especially problematic for sensors used in industrial or environmental applications where samples may include significant concentrations of chlorides or sulfur-based compounds. In these situations, it is essential to utilize high-quality reference electrodes that are resistant to reference poisoning and to keep them clean and well-maintained. Additionally, it is essential to choose a reference electrolyte that is compatible with the sample in order to reduce the possibility of reference poisoning.

In addition, pH sensors with built-in protection against reference poisoning can be used to reduce the negative impact of chlorides and sulfur-based substances on pH sensors. Typically, these sensors utilize a reference electrolyte that is less prone to react with chlorides or sulfur-based substances, and they may also include a protective coating to prevent reference poisoning.

In conclusion, chlorides and sulfur-based chemicals can have a considerable impact on pH sensors due to their ability to react with the reference electrode, causing it to report erroneous voltages. This can cause the pH sensor to provide erroneous values and perhaps cause sensor failure. To prevent reference poisoning, it is essential to utilize high-quality reference electrodes, keep them clean and well-maintained, and employ a compatible reference electrolyte with the sample.