A multi-element chemical speciation fingerprint for a given material (here Municipal Solid Waste Incinerator bottom ash) can be obtained after chemical speciation modeling of pH dependence test data (CEN/TS 14429) The partitioning can distinguish in distribution of elements between dissolved (free and DOC associated) and particulate phases (Fe and Al oxide sorption, ion exchange on clay, mineral phases, solid solutions, surface precipitation and particulate organic matter). The red circles are the actual measurements of the pH dependence test at L/S=10. This partitioning can only be generated by a full mechanistic modelling approach taking major, minor and trace elements, reactive surfaceses of iron, aluminum and organic matter (dissolved and particulate) into account.