In EDXRF the angle between the incoming X-ray beam and the sample surface (glancing angle) and the angle between the detector and the sample surface define two geometrical configurations schematized in Fig. . The conventional configuration with angles 45°/45° (simply referred as EDXRF) and the configuration with angles 0°/90° commonly referred as Total Reflection XRF (TXRF). The TXRF configuration is mainly selected when the phenomenon of external total reflection of the incoming X-ray beam wants to be exploited, to enhance the analytical sensitivity. This condition occurs when the glancing angle is lower than the critical angle of the sample substrate and an X-ray standing wave (XSW) is generated through the constructive interference of the incident and reflected beams, amplifying the X-ray fluorescence signal of the elements present on the sample surface . When TXRF is combined with X-Ray absorption near edge spectroscopy is also possible to get speciation information . It is worth to notice that the condition of total reflection does not only depend on the glancing angle, and it is strongly related with the sample characteristics, thus leading to multiple experimental cases where the above-mentioned condition is not or only partially fulfilled. In this case, the signal enhancement is absent or reduced and TXRF can be simply considered as a different geometrical variation of EDXRF where the advantage is due to the proximity of the detector to the sample surface enhancing the solid angle of collection . The utilization of instruments at a configuration of 0°-90° allows for the exploitation of signal enhancement at lower angles. This approach can be applied to samples that adhere to the thin film approximation, where a linear relationship exists between fluorescence intensity and element concentration. Determining the critical mass for multielement samples can be challenging. However, the thin film approximation can be verified by examining the direct proportionality between intensity and concentration using reference materials (RM). If the instrument permits angular scanning, the optimal measuring condition for determining an element in a sample corresponds to the maximum point on the angular scan curve. WDXRF spectrometers are equipped commonly with Cu and Mo X-ray tube. Distinguishing themselves from the previously mentioned configurations, WDXRF sample chambers are often maintained under vacuum or controlled atmospheric conditions to minimize interference from air and other gases. WDXRF instruments employ crystal monochromators or analysers to precisely select and disperse X-rays of specific wavelengths. These optics play a critical role in separating the characteristic X-rays emitted by the sample into their constituent wavelengths, facilitating precise elemental identification. WDXRF instruments offer exceptional resolution, and elemental coverage being able to detect light elements up to C under vacuum or excitation power tuning . However, they do have certain drawbacks, such as being time-consuming, especially when analysing a wide elemental range. Additionally, their acquisition and maintenance cost together with the complexity of use can pose challenges. Additionally, most of WDXRF instruments are quite large, demanding substantial laboratory space, require a vacuum environment for operation and pure gas mixtures for operation and stand by. Achieving power optimization is feasible for only a few elements.