Ammonia is a highly reactive gas, an excess of which can lead to eutrophication and acidification of terrestrial and freshwater ecosystems, biodiversity loss and the formation of secondary particulate matter. It originates from both natural and anthropogenic sources, including agricultural related emissions such as manures, slurries and fertiliser application.
Ambient ammonia monitoring can be carried out with two CEH products: a low-cost passive sampler (ALPHA®) and the DELTA® active sampler system. The DELTA® system can also be used to actively sample a wider range of atmospheric species.
The CEH ALPHA® and DELTA® systems
CEH ALPHA® for ammonia monitoring in air
The CEH ALPHA® (Adapted Low-cost Passive High Absorption) sampler is a system designed for the measurement of the concentration of ammonia (NH3) in air. It does not sample ammonium aerosol. It is useful as a complementary method for assessing spatial differences in source areas where NH3 concentrations may vary hugely. The method does not require electricity.
Suitable range of ammonia concentrations:
Monthly monitoring = 0.02 - 100 ug NH3 m-3
Weekly monitoring = 0.05 - 400 ug NH3 m-3
The passive sampling system consists of three replicate ALPHA® samplers attached to the underside of a shelter at about 1.5m height above ground. The samplers operate on the principle of diffusion with an acid-coated filter which serves to capture the ammonia. More details of the scientific background and operation are supplied with the samplers. Replicate tubes are used in order to give more reliable results.
Above: Outline diagram of a single ALPHA® sampler and components.
All of the plastic components of the ALPHA® samplers, including the PTFE membranes, can be cleaned and reused. The only component that is single use is the filter paper. You can select which components you require on our order form and we will supply a quote. Details of what is available can be found below:
Can be cleaned for re-use. Does not require electricity. Includes velcro patches to stick to shelter. Minimum order 20.
27mm PTFE membrane can be cleaned for re-use. One per ALPHA® sampler required. Minimum order 20.
24mm diameter cellulose filter circles (used once and replaced). Available in packs of 500 or 1000.
To house three samplers.
Exposed samples are stored at 4˚C until analysis. The chemical of interest captured on the filter paper or denuder tube is extracted, usually into deionised water, which is then analysed. At CEH we use AMFIA (AMmonia Flow Injection Analysis system) for ammonium analysis or Ion chromatography for other chemicals of interest. We use a set of standards and quality control samples to ensure accurate results.
Manual and help videos
How to prepare a CEH ALPHA® sampler
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