Portable XRF for paintings and metals authentication: a critical guide to some practical limitations and multi-technique integrations

In authentication studies, chemists, scientists, art historians, conservators, and law enforcement collaborate to identify forgeries. For paintings, pigment characterization (detecting anachronistic materials) is decisive. Portable X-ray fluorescence spectrometry (pXRF) is a dominant, versatile, non-destructive identification method, yet its misuse is documented and widespread. Literature and current results require contextualization by instrument and era, avoiding over-interpretation. This practical review examines pXRF’s strengths and constraints through case studies.