The presence of metallic deposition and oxides at the surface of insulators used in plasma focus discharges is expected to have a significant effect in the conditioning process that leads to neutrons and hard x-rays emissions. In this work, the atomic concentrations of the main elements present in these insulators are studied by energy dispersive x-ray (EDX) analysis. Preliminary results are presented. Surface oxidation was observed after the conditioning process. A significant concentration of metallic deposition from the anode is observed after a working cycle of a thousand shots.