A single sample for dilution in 2 litres.Sample TargetConcentrationAmmonia as N . 0.65 - 19 mg/L Nitrate as N . 0.25 - 5 mg/LNitriate + Nitrite as N . 0.25 - 40 mg/L Orthophosphate as P . 0.5 - 5.5 mg/L