Which source materials are primarily authored in the calibration procedures for XRF?

The primary source materials used in the calibration procedures for X-ray fluorescence (XRF) are cobalt-57 and cadmium-109. Both of these materials are isotopes that emit specific X-rays when excited.

In XRF analysis, calibration is crucial for accurate measurement of element concentrations in samples. Cobalt-57, with its gamma emissions, is commonly used for calibrating XRF instruments because it has well-defined energy peaks. Cadmium-109 is often used in a similar manner due to its ability to emit X-rays at distinct energy levels that can serve as reliable calibration standards.

The other materials listed do not serve the same purpose in the context of XRF calibration. Gold and silver, while important in some types of analyses, do not represent standard calibration sources for the energy ranges required in XRF. Lead and mercury, although they are commonly detected elements in XRF applications, are not typical sources for calibration standards themselves. Uranium and thorium, similarly, are not utilized for calibrating XRF systems, as their emissions do not align with the calibration needs of XRF methods.

Thus, cobalt-57 and cadmium-109 are the correct choice because they ensure accurate and reliable quantification in XRF analysis through their