Analysis of synthetic humic substances for medical and environmental applications by capillary zone electrophoresis Ph. Schmitt-Kopplin, D. Freitag, A. Kettrup, N. Hertkorn, U. Schoen, R. Klöcking, B. Helbig, F. Andreux and A.W. Garrison Analusis, 27 5 (1999) 390-395 DOI: 10.1051/analusis:1999270390