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XRF is generally considered a nondestructive analytical method in the sense that a specimen is not altered by the analytical procedure. This study is related to paintings and illuminated manuscripts, where the analytes are often inorganic pigments embedded into organic matrices such as fabrics (canvases), paper or parchment, binders, and varnish. We found that a typical measurement cycle with conventional tubes and energy dispersive systems (e.g., 100 s, 100 W tube-power) causes no visible harm. However, 3 kW radiative power for several minutes and more (as often required for wide angle scans as well as for the analysis of light elements or traces in a wavelength dispersive spectrometer) can leave visible traces of permanent yellowing, brittleness, and even mechanical decomposition. In such cases scanning electron microscopy-images indicate permanent alteration of the cellulose fibers and, in paper, of the binder. Employment of modern X-ray optical devices which focus the photons of a wide beam onto a small spot may also leave visible (and invisible) traces of destruction.

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The authors present and discuss a method for simultaneous quantitative analysis of total loss on ignition (LOI) (CO2 + H2O) and CO2 content separate from the LOI, in an industrial environment of quicklime production. Total LOI is determined by the Compton scattered RhKα tube radiation which is used directly in the calibration equation. The resulting calibration curve for LOI, including matrix correction shows an accuracy of 0.15 mass%. The carbon content (CO2) is distinguished from total LOI by measuring CKα radiation, which is possible with the required accuracy by employing a new multilayer analyzer with greatly improved background characteristics. The method aims at high reliability and sample throughput and at becoming a less time-consuming alternative to the conventional method of LOI determination by weighing sequences before and after “ignition” at 1050 °C.

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