Abstract: Method for processing digital image data for a two-dimensional array of sample substance spots and marker substance spots in an electrophoresis gel by using landmark substances having predefined properties, comprising the steps of:generating an ideal image represented by co-ordinate data corresponding to ideal positions of the marker substance spots in said array dependent on electrophoresis conditions; generating a marker image represented by co-ordinate data corresponding to detected positions of said marker substances spots in the array; determining a mathematical relation between the ideal image and the marker image, such that the co-ordinate data of said images are mapped onto each other; generating a sample image represented by a sample image data set corresponding to detected signal values in the gel; and normalising the sample image by transforming it dependent on said mathematical relation.

Abstract: Marker compounds suitable for gel electrophoresis are disclosed. The compounds are natural, non-natural compounds or a mixture thereof, but not a protein. The compounds comprise at least one monomer unit, at least one functional group unit and optionally at least one core unit. Also contemplated is a method for positioning the marker compounds or a set of the compounds according to the invention and a method for the detection and/or quantification of s sample molecule in a two-dimensional gel.