Abstract |
Interlaboratory studies were conducted on selected chemical methods of analysis for ammonia nitrogen, nitrate nitrogen, Kjeldahl nitrogen or organic nitrogen, orthophosphate and total phsophorus. Samples were prepared in pairs at similar yet different concentrations for each constituent. Analysts added an aliquot of each concentrate to distilled water and to a natural water of their choice. Single analyses were made on the distilled and natural water samples with and without added increments. Recoveries were compared and the bias of the method, the interference of natural water samples and the relative precision of each analyst and laboratory were determined. |