Determination of phosphorus in raw materials for ceramics: comparison between X-ray fluorescence spectrometry and inductively coupled plasma-atomic emission spectrometry

This paper compares methods for phosphorus determination in refractory silicoaluminous materials based on inductively coupled plasma-atomic emission spectrometry (ICP-AES) and X-ray fluorescence (XRF) spectrometry. Chemical interferences were studied by using several calibration standards and standard additions. The limits of detection obtained by XRF spectrometry (0.03 and 0.06mg P2O5 per gram of sample) are clearly advantageous as compared with those obtained by ICP-AES (0.2mgg-1). Phosphorus can successfully be determined by XRF spectrometry with either pressed sample pellets or diluted sample beads. Matrix effects were minimised by using a certified bauxite as a standard, but several less-similar materials could be used, such as siderurgic slag, chamotte and even dolomite for low P2O5 content samples. The linear calibration range is larger (up to 100mgg-1) when analysis is carried out by ICP-AES, using the 213.628nm line. Repeatability is similar with both methods, but XRF spectrometry is preferred on the grounds of the better sensitivity achieved, and the simpler sample preparation requirements.