New nitrogen detector

Jon Lawson

Designed with advanced ion selective electrode (ISE) sensors and a highly intelligent transmitter, the new plug-and-play Ammonium Hydra-DS Analyser from Electro-Chemical Devices simplifies the accurate measurement of harmful nutrients (nitrogen) over a broad range to help assure water quality.

It measures the nutrient load in rivers, streams and lakes as well as wastewater treatment plant aeration basins. It determines the concentration of dissolved ammonium as nitrogen (NH4+-N [nutrients]). The sensor uses three electrodes to determine the concentrations: ammonium, potassium and pH (acidity versus alkalinity levels).

Its dependable NH4, K+ and pH ISE sensors are fully compensated for interferences and temperature variability to ensure reliable performance.  The sensors are housed in a rugged, removable PVC tube guard for easy access. A built-in spray cleaner provides in-situ cleaning for automated, predictive maintenance with pressurised water or air to prevent algae or other film growths and to avoid technician cleaning labour.

The NH4 electrode provides primary sensing and measurement. Any potassium ion in the sample generates a positive (K+) interference in the measurement due to its similar size and charge to the NH4 ion. The K ion electrode measures the amount of potassium ion present in the sample, and the T80 Transmitter subtracts the appropriate amount of signal from the measurement.

The NH4 ion electrode only measures the ammonium ion (NH4+) - not ammonia (NH3). The ammonium ion and ammonia coexist in a pH dependent ratio in solution. The more acidic pH values favour the NH4+ and the more basic values favour dissolved ammonia gas (NH3). The pH electrode measures the pH, and the analyser’s T80 Transmitter calculates the total NH4+-N level based on the pH versus NH4+ concentration profile stored in the instrument.

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