Titanium detection by ESI and pEELS. A and B show an energy loss imaging (ESI) series of the L3 orbital of Ti at 440 eV (background) and 464 eV (signal) in an erythrocyte culture. In C, the resulting difference is calculated, revealing the distribution of Ti in the sample. Not shown, but used in the three-window calculation of the Ti distribution is a second background window recorded at 390 eV. The occurrence of Ti is confirmed by parallel electron energy loss spectroscopy (pEELS), shown in the graph. The energy a beam electron looses when interacting with the sample is representative for the atom and orbital it is interacting with. The graph shows a peak intensity around 460 eV, indicative for the interaction with the L3 orbital of Ti (the background follows a negative exponential progression). The zeroloss overview and detail images show a dark particle near a red blood cell. With pEELS confirming the occurrence and ESI revealing the distribution, the particle can be appointed as containing Ti. Bars = 1 μm (D), 250 nm (A to F except D). Titanium dioxide particles were incubated with erythrocytes and fixed and embedded conventionally. The section was placed on a Ni-grid. No supportive film and no staining were used. Zeroloss measuring of the relative thickness of the section at 10 different positions revealed a t/λ of 0.38 (+/- 0.04).