We can get the first confirmation of these differences by measuring the respective intrinsic metal dissolution profiles of activated Pt-alloy electrocatalysts using a wellestablished highly sensitive method, namely electrochemical flow cell (EFC) coupled to an inductively coupled plasma mass spectrometer (ICP-MS). This advanced electrochemical characterization method allows us to track on-line time-and-potential-resolved dissolution of metals (Figures ; see also SI, Figure ). Other variations of the methodology used by other research groups, instead of the EFC, include usage of a scanning flow cell (SFC) or a variation used in combination with an RDE system . The intrinsic metal dissolution was monitored in accordance with the protocol presented in Figure .