On this page
Ammonia reagents and ammonium reagents are the chemical kits that enable online analysers to measure dissolved nitrogen species accurately in drinking water and wastewater. These reagent kits drive the colour reaction in low-level ammonia colourimeters and provide the calibration and stability that intake protection and effluent compliance rely on.
Online Reagents manufactures ammonia and ammonium reagent kits in the UK, specifically formulated for online analysers used across water and wastewater treatment. With over 50 years of experience in water treatment chemistry, we supply consistent, batch-controlled reagent kits that can be ordered directly online for both new and legacy instruments.
What are ammonia reagents and ammonium reagents?
In water treatment, ammonia and ammonium are two forms of the same nitrogen species. Ammonium is the protonated form. Ammonia is the deprotonated form. The balance between the two depends on pH and temperature.
Ammonia reagents and ammonium reagents are the chemical solutions used by online monitors to convert these dissolved species into a measurable signal. Depending on the analyser, this signal may be:
- A colour change measured by a colorimetric ammonia monitor
- A potential measured by an ion-selective electrode (ISE) for ammonium
The role of the reagent kit is to:
- Buffer the sample to the correct pH for the chemistry.
- Drive the reaction that forms a coloured complex in colorimetric methods.
- Condition the sample for an accurate, stable electrode response in ISE methods.
- Provide consistent performance across batches, seasons, and sites.
At Online Reagents, we manufacture both ammonia reagents for colorimetric analysers and reagents for ISE based systems. This supports utilities and industrial users running mixed fleets of instruments.
Why online ammonia and ammonium monitoring matters
Ammonium is a crucial component of the nitrogen cycle, and ammonia is a key indicator for process performance and environmental risk.
Typical applications include:
- Drinking water intake protection
- Online ammonia monitors are positioned at the front end of the works.
- Early warning of pollution events that could threaten raw water quality.
- Wastewater treatment works
- Ammonia monitoring at the inlet to understand load and process demand.
- Ammonia monitoring at the outlet for compliance with consent conditions and process control.
- Industrial effluent and trade waste
- Ensuring compliance with discharge permits.
- Optimising biological and chemical treatment stages.
Reliable measurements depend on reagent kits that match the analyser method and are manufactured to tight tolerances. Poor-quality reagents lead directly to unstable readings, drift, and unnecessary site visits.
Colorimetric ammonia reagents for low-level monitoring
Low-level online monitors generally use colorimetry because it offers high sensitivity at low concentrations. In this approach, ammonia reagents are used to create a coloured compound that is measured photometrically.
A typical colorimetric ammonia method uses salicylate chemistry:
- The sample is buffered to the correct pH using a reagent buffer.
- Sodium dichloroisocyanurate is hydrolysed to form hypochlorite.
- Hypochlorite reacts with ammonia in the sample to form monochloramine.
- Monochloramine reacts with salicylate in the presence of nitroprusside.
- This produces indophenol blue, a coloured complex.
- The analyser measures absorbance at around 660 nm.
- The colour intensity is proportional to the ammonia concentration.
Because the sample is buffered first, both ammonia and ammonium present in the original water are brought to a defined equilibrium and measured together. Results are typically expressed as mg/L nitrogen to avoid confusion over which form was present in the raw sample.
Online Reagents manufactures complete colourimetric ammonia reagent kits for this method, including:
- Buffer reagent
- Dichloroisocyanurate-based oxidising reagent
- Salicylate reagent with a catalyst
- Cleaning or conditioning solutions are required by the analyser
These kits are formulated to provide:
- Stable colour development at 660 nm
- Minimal blank and low detection limits for drinking water and treated effluent
- Consistent batch-to-batch performance with full traceability
Ammonium reagents for ion-selective electrode systems
For higher ammonia loads and broader ranges, many plants use ammonium ion-selective electrodes. In this case, the analyser measures the activity of ammonium ions directly instead of a colour change.
Key points:
- The ISE responds specifically to ammonium in the sample.
- pH and temperature are measured at the same time.
- Using pH, temperature, and the ammonium reading, the analyser can calculate the equivalent ammonia concentration if required.
- Results are often reported as mg/L nitrogen, which removes issues around speciation.
Ammonium reagents for ISE systems are primarily used to:
- Maintain a consistent ionic strength in the sample.
- Control pH to keep the electrode response predictable.
- Regenerate or clean the electrode where site conditions are aggressive.
Online Reagents supplies ammonium reagent kits tailored for ISE-based ammonia systems. These are configured to match the dosing, sampling, and calibration routines of specific analyser models.
Expressing results in mg/L nitrogen
One challenge in ammonia monitoring is that the same nitrogen can appear as ammonia or ammonium, depending on pH and temperature. To avoid confusion, both colorimetric and ISE approaches in modern online analysers typically report results as mg/L nitrogen.
Advantages of reporting in mg/L N include:
- Direct comparability between sites using different methods
- Easier comparison with consent limits expressed as nitrogen
- Reduced risk of misinterpretation where speciation changes in the process
Reagents manufactured by Online Reagents are designed with this in mind. Methods and calibrations follow mg/L nitrogen conventions and are compatible with common regulatory reporting formats.
Why choose Online Reagents for reagent kits
Online Reagents has over 50 years of experience manufacturing reagents for water and wastewater analysis. For ammonia reagents and ammonium reagents, this translates into:
- Proven formulations for salicylate-based colorimetric ammonia methods
- Reagent kits configured for both low-level drinking water monitoring and higher range wastewater applications.
- Ammonium reagent solutions compatible with leading ISE-based analyser platforms
- UK-based blending, batch control and QA with full traceability
- Flexible pack sizes and concentrations aligned to your changeover schedule
- Online ordering so that plants, framework partners and OEMs can re order quickly
Because we focus on reagent manufacture, not instrument sales, we are well placed to support mixed analyser estates with consistent chemistry and harmonised methods.
Typical questions about ammonia reagents and ammonium reagents
Are your ammonia reagents suitable for low-level drinking water applications?
Yes. Our colorimetric ammonia reagent kits are designed for low-level monitoring using salicylate chemistry, offering high sensitivity and low blanks suitable for drinking water intake protection and treated water surveillance.
Can I use the same ammonia reagent kit on different analyser brands?
Reagent chemistry may be similar, but each analyser has its own dosing sequence, volumes and reaction timings. Online Reagents can review your instrument types and supply compatible ammonia and ammonium reagent kits configured for each platform.
Do your ammonium reagents work with ISE-based systems only.
Yes. These reagent kits are intended for ion-selective electrode-based systems that measure ammonium directly and calculate ammonia based on pH and temperature. If your analyser is colorimetric, you will require ammonia reagent kits instead.
Can you provide private-label ammonia reagent kits?
We can supply reagents under private label for OEMs and service partners, with agreed formulations, packaging and documentation.
If you operate online monitors and need reliable ammonia reagents or ammonium reagent kits, you can order directly through Online Reagents. Our technical team can help you match the right reagent kit to your analyser type and process conditions and put in place a stable, long term supply for your sites.
