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 | 0.948 | 0.920 - 0.975 | 0.750 - 1.146 |
Nitrate-Nitrogen (as N) | mg/l | 0.706 | 0.692 - 0.720 | 0.611 - 0.801 |
Orthophosphate (as P) | mg/l | 0.818 | 0.807 - 0.829 | 0.741 - 0.895 |
Total Kjeldahl Nitrogen | mg/l | 1.95 | 1.84 - 2.06 | 1.26 - 2.64 |
Total Phosphorus (as P) | mg/l | 0.834 | 0.818 -0.851 | 0.719 - 0.950 |
These values were the result of an inter-laboratory study involving 27 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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