PBM can be analyzed using scanning electron microscopy coupled to energy dispersive spectroscopy (SEM-EDS). The samples are metallized with a few nanometers of graphite and analyzed at a 15-kV acceleration voltage, 700 pA electron current, and at a 9–10 mm working distance. The analysis protocol is developed to standardize the measurements and quantify the particles composed of heavy metals in a faster and accurate way. Samples are previously investigated using an automatic procedure that allowed to select the standard surface area of each sample to be investigated and a suitable magnification to identify the particles. Selecting backscattered electrons images with an appropriate black and white image threshold, the program is able to identify all particles comprising the selected thresholding levels, to morphologically measure them, to perform a rapid EDS (10-s of live-time) analysis, and thus chemically classify all particles. Heavy metal particles are recognized as light grey areas using backscattered electrons images with a contrast of 60%, brightness of 5–10%, and a threshold shade of grey (between 80 and 250) able to include all particles with an average atomic number (Z), heavier than Ba (reference standard BaSO₄) (Figure 1). These methods allow the isolation of particles characterized by a high average Z, comprising (but not exclusively) those containing Hg. It has to be stressed that, on the basis of backscattered electrons (BSE) thresholder images, the dimension (equivalent circular diameter, ECD) of the identified particles is smaller than the X-ray generation volume (i.e., the volume from which X-rays are produced). We can estimate an interaction volume with a diameter of about 0.8–1.1 µm (respectively at 10–20 kV acceleration voltages) for heavy elements/compounds (density > 8 g/cm³, i.e., Cu), and even greater (some microns) for light elements. To restrict SEM-EDS microanalyses to the volume of Hg particles, minimizing the contribution of the surrounding phases, a more detailed microanalysis (30-s of live-time) can be selectively conducted on the largest Hg-particles (i.e., ECD > 1 µm or the largest for each sample). All elements are re-calculated using a microanalysis software, which used the XPP matrix correction scheme developed by Pouchou and Pichoir^[7]. This is a Phi-Rho-Z approach which uses exponentials to describe the shape of a φ(pz) curve. The procedure is a “standard-less” semi-quantitative analysis employing pre-acquired standard materials. The monitoring of the analytical conditions (i.e., filament emission) is conducted with repeated analyses of a Co metallic standard