A method of ion mapping is disclosed comprising depositing a sample onto a target surface and separating the sample on the target surface according to a first physico-chemical property in a first dimension and according to a second physico-chemical property in a second dimension. The method further comprises ionising and mass analysing multiple separate regions of the sample so as to generate an ion map of at least a portion of the sample deposited upon the target surface. The sample is deposited onto and separated on the target surface by mechanical, hydrodynamic and/or aerodynamic means.