Determination of Phosphorus, Potassium, and Magnesium in Fertilizers by Inductively Coupled Plasma–Atomic Emission Spectroscopy and Comparison with Other Techniques

Phosphorus, potassium, and magnesium in 12 fertilizers were determined by inductively coupled plasma–atomic emission spectroscopy (ICP–AES), and results were compared with those obtained by standard gravimetry (phosphorus) and atomic absorption spectrometry (AAS) (potassium and magnesium). ICP–AES and gravimetry were also used to determine water- and citrate-soluble phosphorus in fertilizers. In all cases, precision and accuracy of the ICP–AES method were satisfactory. Certain differences, probably not significant for routine analyses, were observed between ICP–AES and gravimetry in determinations of total and citrate-soluble phosphorus when the measurements were performed strictly under conditions of repeatability.