In TXRF, samples are typically direct analysis, eliminating the need for extensive digestion procedures or dealing with difficult sample matrices. This approach drastically reduces the complexity of sample preparation. Furthermore, TXRF demands only few sample portions, making it exceptionally suitable for situations where sample quantity is limited. TXRF offers outstanding surface sensitivity, positioning it as the technique of choice for thin films, coatings, or surface layers. In contrast, ICP-MS, while incredibly sensitive, primarily provides bulk analysis and may not distinguish surface composition from interior composition as effectively. One noteworthy advantage of TXRF is its reputation as an environmentally friendly technique. TXRF reduces the uses of harmful reagents and minimized generation of chemical waste, meeting the principles of green chemistry." Although significant progress has been made in the XRF methods, comparable results with those obtained through standardized spectroscopic techniques, a recurring challenge emerges in various studies: the lack of certified reference materials. Consequently, considerable efforts have been dedicated to the development of both mono-element and multi-element reference materials . Despite the validation of XRF measurements against other established methods like ion chromatography and ICP-MS for specific elements, the absence of a universally accepted Reference Method for determining the elemental content of PM makes difficult to choose the best analytical method. They are often considered as complementary to each other. This highlights the pressing need for universally recognized reference materials that rigorously assess all aspects of the measurement process, a necessity for the atmospheric PM monitoring community.