This Performance Evaluation Standard is in the form of a concentrate prepared by weight and does not require digestion. Dilute to 1L before use.
Typical values:
Parameter | Unit | Consensus Value | Confidence Interval | Tolerance Interval |
Ammonia-Nitrogen (as N) | mg/l | 8.5 | 8.35 - 8.66 | 6.94 - 10.07 |
Nitrate-Nitrogen (as N) | mg/l | 13.3 | 13.0 - 13.6 | 10.8 - 15.7 |
Orthophosphate (as P) | mg/l | 4.47 | 4.36 - 4.57 | 3.60 - 5.34 |
Total Kjeldahl Nitrogen | mg/l | 19.6 | 19.0 - 20.2 | 15.1 - 24.0 |
Total Phosphorus (as P) | mg/l | 4.66 | 4.58 - 4.74 | 4.05 - 5.27 |
These values were the result of an inter-laboratory study involving 18 international laboratories. Each laboratory was asked to supply analysis data for a specific list of elements. Not all the laboratories supplied data for the different parameters.
Here is a summary of methods used by most of the participating laboratories for the inter-laboratory study:
Ammonia as N: Colorimetric method, Molecular Absorption spectroscopy, ISE
Nitrate as N: Colorimetric method, IC
o-Phosphate as P: Colorimetric method, Molecular Absorption spectroscopy, IC
Total Kjeldahl Nitrogen: Colorimetric method, ISE
Total Phosphorus: Colorimetric method, ICP-MS, ICP-OES
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