“Chemical analysis was performed using a Thermo Scientific Niton XLt-900 XRF Analyzer equipped with a GOLDD X-ray fluorescence detector and real-time digital signal processing at a speed of 80 MHz. The XRF measurements were taken in the laboratory, using a Thermo Scientific SmartStand, ensuring consistent positioning. Since the Niton pXRF is programmed to utilize predefined matrices provided by the manufacturer, the “General Mining” matrix, which includes the relevant metallic and non-metallic elements, was selected for the current research. Calibration was performed using an internal calibration system defined by the manufacturer and validated using a known standard (SRM 2780).”<p>Translation: “We used a closed-source proprietary method by a manufacturer and validated it on a sample the manufacturer recommended.”<p>XRF generates spectra which represent atomic abundance (eg K-, L-, and M-line emissions). However, these are not international standard units. Laboratory units translate from spectra to mass fraction through meticulous preparation of standards. Handheld units often use a secret sauce algorithm to do this to keep analysis non destructive. I’m skeptical of the results - but what’s more important is that these results are not fully reproducible. If the company goes belly up, or less dramatically changes/updates the proprietary algorithms used to create mass fraction estimates, the reported results of this study won’t be replicable even with the same samples.