Modifications to the standard additions method for components at very high concentrations

Limitations to the classical methods of standard additions (MSA) are discussed and overcome by the proposed modifications to the method. The modifications permit accurate linear regression determination of analytes at very high concentrations (>5%) in complex materials where matrix matching is difficult or where appropriate standard reference materials (SRM) are not available. The modifications are demonstrated with X-ray diffraction (XRD) determination of θ (56.5%) and amorphous (23.9%) phase concentrations in fumed alumina, which contains a variety of crystalline phases. The modified method may be especially suited to analysis of solids and powders with techniques such as XRD, X-ray fluorescence (XRF), and Raman spectroscopy where similar very high-analyte concentration and sample matrix complexity are commonly encountered, provided that the assumptions of the method can be met.