Fluorescent dissolved oxygen electrode due to itsNo need for electrolyte, no need for polarization, and no interference from hydrogen sulfideDue to its advantages, it has become the mainstream choice in the field of water quality monitoring. Understanding its lifespan and maintenance points is crucial for ensuring measurement accuracy and extending equipment investment returns.

1Fluorescent dissolved oxygen electrodeThe service life

The lifespan of fluorescent electrodesNot a fixed timeIt is influenced by various factors and is usually longer than traditional electrochemical electrodes.

1. Typical service life range

　　Under normal use and maintenance:Its core components——Fluorescent film capThe lifespan is usually within1 to 2 years.

　　In harsh environments:If the sample contains a large amountOrganic solvents, strong acids, strong bases, high salinity, or frequent exposure to pollutants such as oil stains and proteinsThe lifespan may be shortened to6 months to 1 year.

　　Whole electrode:In addition to the membrane cap, the electronic and optical components inside the electrode have a long lifespan, and as long as they are not damaged, the entire electrode body can be used for many years. Therefore,The replacement cost is mainly concentrated on the membrane cap.

2. Key factors affecting service life

　　Physical wear and contamination:

　　Scratching:The fluorescent substance on the surface of the membrane cap is very fragile, and any hard object scratching will damage its performance.

　　Biological pollution/scaling:The biofilm formed by microbial growth and the deposition of minerals (such as calcium and magnesium) in water to form scale can block the contact between oxygen and fluorescent film, leading to reading drift or inaccuracy.

　　Chemical erosion:

　　Solvent class:Organic solvents such as alcohol, acetone, and chloroform can dissolve or damage fluorescent film materials.

　　Strong acid and strong alkali:Environments with excessively high or low pH values can accelerate the aging of membrane materials.

　　Sulfur containing compounds:Although the fluorescence method itself is not affected by H ₂ S interference, high concentrations of sulfides may still cause long-term damage to the membrane.

　　Mechanical impact and improper operation:

Falling or impact can cause internal optical path deviation or membrane cap rupture.

Use sharp tools to clean and forcefully install/remove the film cap.

　　Improper storage:

Long term storage in a dry environment may cause the film cap to dry and crack.

Storing in liquids containing pollutants can cause contamination of the membrane cap.

2、 Maintenance method of fluorescent dissolved oxygen electrode

The core principles of maintenance are:Keep the membrane cap clean and intact, and avoid physical and chemical damage.

1. Daily use and cleaning maintenance

　　Regular cleaning (most important!):

　　frequencyDetermine based on the water sample situation. In clean water, it can be done once a week or once a month; In wastewater, fermentation broth, and high organic matter water bodies, it is recommended toClean after each use.

　　Method:

Remove the electrode from the water sample.

Gently rinse the electrode surface with deionized water or distilled water to remove most of the attached substances.

Dip a small amount of soft sponge or cloth (such as laboratory specific dust-free cloth) into itClear water or mild neutral detergent solutionGently wipe the membrane cap area.Do not use rough tissues, sandpaper, or steel wire balls!

Rinse with clean water and use a soft cloth to absorb surface moisture, or let it dry naturally before putting it back into the storage solution.

　　Stubborn stain treatment:

If encountering stubborn stains of oil or protein, diluted ones can be usedProtease solutionSoak and gently wash (such as dishwashing detergent) for a few minutes, then rinse with clean water.

　　Strictly prohibited from useWipe or soak the film cap directly with organic solvents (such as alcohol, acetone)!

2. Calibration and maintenance

　　Calibration frequency:

Fluorescence method electrodeNo need for frequent polarization or calibration like electrochemical electrodes.

It is recommended to calibrate in the following situations:

　　After replacing the new membrane cap.

When there is a significant deviation or drift in the measurement results.

Perform confirmatory calibration at regular intervals (e.g. 1-3 months, depending on usage frequency and environmental stability).

　　Calibration method:

　　Zero point calibration (anaerobic environment):Immerse the electrode in an anaerobic solution (usually sodium sulfite solution) and perform zero point calibration after the reading stabilizes.

　　Slope calibration (saturated air environment):Place the electrode in air (ensuring constant temperature and humidity close to 100%), and after the reading stabilizes, calibrate it to the saturated dissolved oxygen value of the air at the current temperature (obtained from a table).

　　Note:Please refer to the instruction manual for the brand and model of electrode you are using for specific calibration steps, as there may be slight differences in the operating interface and process of instruments from different manufacturers.

3. Storage and maintenance

　　Short term storage (hours to days):

Can be soaked inAir environment with saturated humidityIn the middle, or directly stored indeionized waterIn the middle.

　　Long term storage (several weeks or more):

　　Best way:Store the electrodes inSpecialized electrode preservation solutionIn the middle. This solution can keep the membrane cap moist, prevent drying and cracking, and inhibit microbial growth.

　　Secondary option:Stored inDeionized water or distilled waterHowever, it should be noted that long-term immersion in water may also lead to microbial growth, and it must be cleaned before reuse.

　　Absolutely prohibited:Store in a dry environment or in liquids containing pollutants.

4. Preventive maintenance and inspection

　　Regular inspection:Regularly observe the surface of the membrane cap under a microscope or through a magnifying glass for scratches, cracks, discoloration, or deposition of contaminants. Once serious damage is found, the membrane cap should be replaced immediately.

　　handle gently:Be careful when handling electrodes at all times to avoid collisions and drops.

　　Correct installation:According to the instructions, gently tighten or clamp the film cap without excessive force.

3、 When is it necessary to replace the membrane cap?

When the following situations occur, it indicates that the membrane cap has failed and must be replaced:

　　The reading remains unstable or drifts significantlyAnd it cannot be restored after cleaning and calibration.

　　Response time significantly slows downThe transition from a saturated state to an anaerobic state takes a long time.

　　There is a significant error in the readingFor example, readings in the air are far below the theoretical saturation value and have no discernible pattern.

　　Visible physical damage on the surface of the membrane capSuch as scratches, cracks, damages, or spots.

　　Achieve the manufacturer's recommended maximum service life(Even if it looks intact).