Rapid determination of nitrogen, phosphorus and potassium in fertilisers by flow injection analysis

Abstract

Based on the flow injection technique and routinely using sample injections of 30 µl, and as low as 5 µl, reliable and sensitive methods for the determination of nitrate, potassium, phosphate and ammonia in fertilisers are described in which potentiometric and spectrophotometric detection is used. At sampling rates of 85–120 samples per hour high reproducibility of measurement and low reagent consumptions were achieved. The good agreement between the results obtained with the flow injection methods and those attained by the manufacturer of the fertilisers with conventional techniques shows that flow injection analysis is potentially suitable for the routine analysis of these and similar substrates.