The most common method to measure dissolved oxygen (O2) in water is by using a dissolved oxygen meter with a sensor.
Types of Dissolved Oxygen Sensors
Dissolved oxygen sensors come in two main types:
- Optical Sensors: These sensors use light to measure oxygen levels.
- Electrochemical Sensors: These sensors rely on chemical reactions to determine oxygen concentration.
Electrochemical sensors can be further categorized into:
- Polarographic Sensors: These sensors apply a voltage to create an electric current that's proportional to the oxygen concentration.
- Pulsed Polarographic Sensors: These sensors are a variation of polarographic sensors that apply voltage in pulses to improve performance and minimize interference.
- Galvanic Sensors: These sensors generate their own current based on the oxygen level in the water sample.
Detailed Information on Measurement Methods
Here's a table outlining the methods and sensor types:
| Method | Sensor Type | Principle |
|---|---|---|
| Most Popular Method | Dissolved Oxygen Meter and Sensor | Measures the dissolved oxygen level directly. Can use optical or electrochemical sensors for the measurement. |
| Electrochemical | Polarographic | Applies a voltage, creating a current proportional to oxygen concentration. |
| Electrochemical | Pulsed Polarographic | Applies pulsed voltage, enhancing accuracy and minimizing interference. |
| Electrochemical | Galvanic | Generates its own current based on the oxygen present in water. |
Practical Considerations
- Calibration: Regular calibration of the dissolved oxygen meter is crucial for accurate readings.
- Temperature Compensation: Dissolved oxygen levels are affected by temperature, so most meters incorporate temperature compensation.
- Sensor Maintenance: Proper care and maintenance of the sensor are essential for its longevity and accurate measurements.
Example of using a Dissolved Oxygen Meter
- Preparation: Ensure the meter is calibrated according to manufacturer instructions and the sensor is ready.
- Sample Measurement: Submerge the sensor into the water sample, allowing sufficient time for the reading to stabilize.
- Reading: Record the measurement displayed on the meter.
- Data Interpretation: Use the reading in your environmental assessments, research or whatever your goal was in taking the measurement.
