Abstract: The invention comprises an apparatus and process for determining the relative proportions by mass of two or more differing substances contained in a sample comprising a combination (e.g. a mixture) of the two or more differing substances.

Abstract: An apparatus comprises a source of penetrating radiation, a detector for that radiation, a sample container, and a stage between the source and the detector for supporting the sample container, wherein the sample container includes a data storage element and the apparatus includes a reader for that data storage element, the reader being connected to a control means adapted to control the apparatus on the basis of the content of the data storage element. Thus, by including information in the data storage element relating to the nature of the sample, the apparatus can be tuned to that type or class of sample and more reliable results obtained. A suitable data storage element is a bar code, and a suitable sample container is a tray.