Major investments are often made in state-of-the-art XRF equipment without knowing that the whole analytical chain, including the weighing step in sample preparation prior to fusion, is of crucial importance to get precise and accurate analytical results and consequently obtain estimated financial pay-offs. In fact, precision and accuracy of results enable the manufacturer to decrease the level of uncertainty associated with the concentrations of its products, and therefore avoid huge losses in revenue.
The weighing step in sample preparation by fusion for XRF analysis is all about knowing the exact weights of the sample and the flux (sample-to-flux ratio). Consequently, the weighing method, the tolerance accepted as well as the analytical method to obtain this ratio will affect the quality of analytical results given by the spectrometer.
There are many ways to weigh the sample and the flux prior to fusion:
• Manual weighing (most widespread technique)
• Automated weighing (with Claisse® LeDoser™ or LeDoser-12™ for example)
• Weighing the sample and the flux directly in the platinum (Pt) crucible
• Weighing the sample or the flux in another container, reusable or not, before transferring it into the Pt crucible
• Pre-weighed flux vials
• Weight correction on the XRF instrument (exact weight needs to be known)
All these weighing methods affect the precision of the sample-to-flux ratio and consequently impact the final analytical results.
In this application note, the effect of the different weighing methods on the precision (RSD) of the obtained XRF results are compared.