Electrode Cleaning Procedure for Online Ammonia Nitrogen Analyzers

Online ammonia nitrogen analyzers require regular electrode maintenance to ensure accurate measurements and extend equipment lifespan. Proper cleaning procedures are essential for reliable performance in water quality monitoring applications.

Before starting the cleaning process, always turn off the instrument and disconnect the power supply for safety. Wear appropriate personal protective equipment including gloves and safety goggles. Prepare all necessary materials: pure or deionized water, soft-bristled brush, lint-free cloth, and suitable cleaning solutions.

For routine maintenance and mild contamination, begin with physical cleaning. Gently rinse the electrode surface with pure water for 10-20 seconds to remove loose residues. Use a soft brush or lint-free cloth moistened with neutral detergent to wipe the electrode membrane, moving in a single direction to prevent damage. Clean threaded interfaces carefully with a soft brush to remove any accumulated deposits.

Chemical Cleaning

For biological films or stubborn organic contamination, chemical cleaning is necessary. Soak the electrode in 0.1% sodium hypochlorite solution for 10-15 minutes to eliminate biofilms. For severe organic contamination, use 3% hydrogen peroxide with an immersion time of 5-8 minutes. When analyzing industrial wastewater containing heavy metals, soak the electrode in 5% EDTA solution for approximately 5 minutes after measurement to remove adsorbed metal ions.

Ultrasonic Cleaning

For microscopic particles that cannot be removed by conventional methods, ultrasonic cleaning is recommended. Use an ultrasonic cleaner filled with pure water or weak alkaline solution, operating at 40kHz for 3-5 minutes.

Post-Cleaning Protocol

After cleaning, thoroughly rinse the electrode with ultrapure water until the electrical conductivity of the rinse water falls below 1 μS/cm. This ensures complete removal of cleaning agents. Allow the electrode to air-dry in a dust-free environment or use oil-free compressed nitrogen for drying. Avoid wiping with cloths to prevent static damage.

Recalibrate the electrode following cleaning procedures. Perform a single-point check using standard solution such as 50 mg/L NH₃-N, with measurement error maintained within ±5%. For monthly maintenance, conduct two-point calibration using 1 mg/L and 100 mg/L solutions, ensuring the correlation coefficient reaches 0.995 or higher.

When the electrode will not be used immediately, store it immersed in protective solution such as 0.1 mol/L NH₄Cl and 0.1 mol/L NaCl mixture. Never allow the electrode to dry out completely as this may cause membrane cracking and failure.