Abstract: The invention relates to a method for the detection of an analyte containing polyamino acid. The object of the invention is to detect polyamino acids in a highly sensitive manner. The object is achieved in that an LM is coupled to a protein after chemical activation, and is complexed using a lanthanoid ion. In order to detect polyamino acids, the time resolved fluorescence measurement is utilized after electrophoretic separation. The detection limit is 0.5 pg per spot (bovine serum albumin), wherein the linear region extends across six orders of magnitude. The invention also relates to analytes containing nucleic acid.