Abstract A large number of polynuclear aza heterocyclic compounds have been separated by paper and thin-layer electrophoresis. The pherograms were scanned fluorimetrically. Many of the separated compounds were capable of being characterized and assayed by the scanning procedure. Analysis by fluorimetric scanning of the pherograms was much more selective when the appropriate excitation and emission wavelengths were used. Samples of urban airborne particulate can be separated and analyzed with the help of paper or thin-layer electophoresis.