Fluorescence dissolved oxygen meter is an instrument used to measure the concentration of dissolved oxygen in water. Dissolved oxygen is one of the important parameters in water bodies. It has an important impact on the survival and reproduction of aquatic organisms. It is also one of the important indicators for measuring water quality. The fluorescence dissolved oxygen meter determines the dissolved oxygen concentration in water by measuring the intensity of the fluorescence signal. It has high sensitivity and accuracy and is widely used in environmental monitoring, water quality assessment, aquaculture and other fields. This article will introduce in detail the working principle, structural composition, usage and application of the fluorescence dissolved oxygen meter in different fields.
1. Working principle
The working principle of the fluorescence dissolved oxygen meter is based on the interaction between oxygen molecules and fluorescent substances. The core idea is to excite fluorescent substances so that the intensity of the fluorescent signal they emit is proportional to the dissolved oxygen concentration in the water. The following is a detailed description of the working principle of the fluorescence dissolved oxygen meter:
1. Fluorescent substances: Oxygen-sensitive fluorescent substances, such as oxygen-sensitive fluorescent dyes, are usually used in fluorescence dissolved oxygen meters. These fluorescent substances have high fluorescence intensity in the absence of oxygen, but when oxygen is present, oxygen will chemically react with the fluorescent substances, causing the fluorescence intensity to weaken.
2. Excitation light source: Fluorescence dissolved oxygen meters are usually equipped with an excitation light source to excite fluorescent substances. This excitation light source is usually an LED (light emitting diode) or laser of a specific wavelength. The wavelength of the excitation light source is usually selected within the absorption wavelength range of the fluorescent substance.
3. Fluorescence detector: Under the action of the excitation light source, the fluorescent substance will emit a fluorescence signal, the intensity of which is inversely proportional to the dissolved oxygen concentration in the water. Fluorometric dissolved oxygen meters are equipped with a fluorescence detector to measure the intensity of this fluorescent signal.
4. Oxygen concentration calculation: The intensity of the fluorescence signal is processed by the circuit inside the instrument, and then converted into a value of dissolved oxygen concentration. This value is usually expressed in milligrams per liter (mg/L).
2. Structural composition
The structural composition of a fluorescence dissolved oxygen meter usually includes the following main parts:
1. Sensor head: The sensor head is the part in contact with the water sample. It usually includes a transparent fluorescent optical fiber or fluorescent diaphragm. These components are used to accommodate fluorescent substances. The sensor head requires special design to ensure that the fluorescent substance is in full contact with the water sample and is not interfered by external light.
2. Excitation light source: The excitation light source is usually located on the upper part of the instrument. It transmits the excitation light to the sensor head through optical fiber or optical fiber to excite fluorescent substances.
3. Fluorescence detector: The fluorescence detector is located at the lower part of the instrument and is used to measure the intensity of the fluorescence signal emitted from the sensor head. Fluorescence detectors usually include a photodiode or photomultiplier tube, which converts optical signals into electrical signals.
4. Signal processing unit: The instrument is equipped with a signal processing unit, which is used to convert the intensity of the fluorescence signal into a value of dissolved oxygen concentration, and display it on the screen of the instrument or output it to a computer or data recording device.
5. Control unit: The control unit is used to set the working parameters of the instrument, such as the intensity of the excitation light source, the gain of the fluorescence detector, etc. These parameters can be adjusted as needed to ensure accurate dissolved oxygen concentration measurements.
6. Display and user interface: Fluorescence dissolved oxygen meters are usually equipped with a user-friendly display and operating interface for displaying measurement results, setting parameters and operating the instrument.
3. How to use
Dissolved oxygen concentration measurement using a fluorescence dissolved oxygen meter usually involves the following steps:
1. Instrument preparation: First, make sure the instrument is in normal working condition. Check that the excitation light source and fluorescence detector are operating properly, the time and date the instrument was calibrated, and whether the fluorescent substance needs to be replaced or recoated.
2. Sample collection: Collect the water sample to be tested and make sure the sample is clean and free of impurities and bubbles. If necessary, a filter can be used to remove suspended solids and particulate matter.
3. Sensor installation: Completely immerse the sensor head into the water sample to ensure full contact between the fluorescent substance and the water sample. Avoid contact between the sensor head and the container wall or bottom to avoid errors.
4. Start measurement: Select Start Measurement on the control interface of the instrument. The instrument will automatically excite the fluorescent substance and measure the intensity of the fluorescent signal.
5. Data recording: After the measurement is completed, the instrument will display the measurement results of dissolved oxygen concentration. Results can be recorded in the built-in memory on the instrument, or data can be exported to an external device for storage and analysis.
6. Cleaning and maintenance: After the measurement, clean the sensor head in time to avoid fluorescent substance residue or contamination. Calibrate the instrument regularly to check its performance and stability to ensure accurate measurement results.
4. Application fields
Fluorescence dissolved oxygen meters are widely used in many fields. The following are some main application fields:
1. Environmental monitoring: Fluorescence dissolved oxygen meters are used to monitor the dissolved oxygen concentration in natural water bodies, rivers, lakes, oceans and other waters to assess the water quality of water bodies and the health of ecosystems.
2. Aquaculture: In fish and shrimp farming, dissolved oxygen concentration is one of the key parameters. Fluorescence dissolved oxygen meters can be used to monitor the dissolved oxygen concentration in breeding ponds or water bodies to ensure the survival and growth of farmed animals. .
3. Water treatment: Fluorescence dissolved oxygen meter can be used to monitor the dissolved oxygen concentration during wastewater treatment to ensure that the wastewater meets discharge standards.
4. Marine research: In marine scientific research, fluorescence dissolved oxygen meters are used to measure the dissolved oxygen concentration in seawater at different depths and locations to study marine ecosystems and marine oxygen cycles.
5. Laboratory research: Fluorescence dissolved oxygen meters are also commonly used in biological, ecological and environmental scientific research in laboratories to explore oxygen dissolution dynamics and biological reactions under different conditions.
6. Brand reputation: Choosing well-known and reputable fluorescence dissolved oxygen meter manufacturers, such as YSI, Hach, Lianhua Technology, Thermo Fisher Scientific, etc., can improve the reliability of the instrument and the quality of after-sales service.
The fluorescence dissolved oxygen meter is a high-precision, high-sensitivity instrument used to measure the dissolved oxygen concentration in water. Its working principle is based on the interaction of fluorescent substances and oxygen, and has a wide range of applications, including environmental monitoring, aquaculture, water treatment, marine research and laboratory research. For this reason, fluorescence dissolved oxygen meters play an important role in maintaining the ecological balance of water bodies and protecting water resources.
Lianhua’s portable fluorescent dissolved oxygen instrument LH-DO2M (V11) uses stainless steel fully sealed electrodes, with a waterproof rating of IP68. It is easy to operate and is a powerful assistant in the detection of sewage, wastewater and laboratory water. The measurement range of dissolved oxygen is 0-20 mg/L. There is no need to add electrolyte or frequent calibration, which greatly reduces maintenance costs.
Post time: Apr-12-2024
