In Progress Lesson 1, Topic 1 In Progress Identifying substances in a chromatogram Identifying substances A chromatogram can be used to identify the components in a separated mixture Rf is the retention factorThe Rf value for a particular substance in a particular solvent is always the same. This means that components can be identified.Chromatography can be used to identify colourless substances by making them visible using a locating agentAmino acids from proteins are colourless and are made visible using a locating agent