Determination of phosphorus in copper-based alloys using ion-exchange chromatography and direct-current plasma emission spectrometry

Phosphorus is determined directly in acid digests of Cu-based alloys by using direct-current plasma emission spectrometry. The spectral overlap interference of Cu and Fe emission on the most sensitive P lines is eliminated by ion-exchange separation carried out in the sample flow stream to the emission spectrometer. The separations involve either a cation exchange to retain the interfering elements on the column or an anion exchange using an activated alumina column to retain and preconcentrate the P. Phosphorus detection limits obtained by using the latter method are 20 times better than those obtained by using continuous aspiration. A detection limit of 10 ng/ml is observed for a 30-min preconcentration time and 2 ml/min sample flow rate. Phosphorus is determined at the 20 mu g/g level in SRM 875 (cupro-nickel, an alloy containing approx 90% Cu and 10% Ni) and in phosphorized Cu SRMs 1251 and 1252 at concentrations from 80-400 mu g/g. 13 ref.--AA