BS ISO 23201:2015 pdf download – Aluminium oxide primarily used for production of aluminium — Determination of trace elements — Wavelength dispersive X-ray fluorescence spectrometric method.
3 Principle A portion of the aluminium oxide test sample is incorporated, via fusion, into a borate glass disc using a casting technique. X-ray fluorescence measurements are made on this disc. Calibration is carried out using synthetic standards prepared from pure chemicals using a two-point regression. Matrix corrections may be employed but, because of the low levels at which the analytes are present in the Al 2 O 3 matrix, will have negligible effect within the scope of the method. Intensity measurements are corrected for spectrometer drift. A certified reference material, (see Annex E) is used to verify the calibration. 4 Reagents and materials 4.1 Flux, mixture of 12 parts lithium tetraborate to 22 parts lithium metaborate, pre-fused. This flux is available commercially. Flux will absorb atmospheric moisture when exposed to air. Minimize water uptake by storing flux in an airtight container. See Annex F for comments on flux purity. 4.2 Aluminium oxide (Al 2 O 3 ), high purity, nominally 99,999 % Al 2 O 3 . Prepared by heating to 1 200 °C± 25 °C for 2 h and cooling in a desiccator. To ensure the high purity Al 2 O 3 is not contaminated with analyte elements, analyse it before use by preparing a disc made from the aluminium oxide (referred to as a “blank disc”) and measuring net intensities for each analyte element. The method for the measurement of blank discs is given in 7.4.5. If a number of differently sourced high purity aluminium oxides are tested select the one with the lowest countrates for impurities for use in calibration and blank discs. A.3 gives instructions for reducing silica contamination in high purity aluminium oxide and may be employed if required. 4.3 Sodium tetraborate (Na 2 B 4 O 7 ), nominally 99,99 % Na 2 B 4 O 7 . Prepared by heating to 650 °C ± 25 °C for 4 h minimum and cooling in a desiccator. 4.4 Silicon dioxide (SiO 2 ), nominally 99,9 % SiO 2 . Prepared by heating to 1 200 °C ± 25 °C for 2 h and cooling in a desiccator. 4.5 Iron(III) oxide (Fe 2 O 3 ), nominally 99,9 % Fe 2 O 3 .