“…Conventional low pressure size-exclusion chromatography (LPSEC) − and high-performance size-exclusion liquid chromatography (HPSEC) ,− are often used to characterize aquatic and terrestrial NOM due to their high fractionation efficiency. To improve information provided by SEC, researchers frequently employed several techniques (UV–visible absorption, carbon content, 2D- and 3D-fluorescence, 1 H- and 13 C NMR, FT-ICR-MS, Pyr-GC-MS) hyphenated in a single analytical chromatographic run ,, or conducted offline. ,,,,,,, For the separation of aquatic and terrestrial humic substances (HS) we have developed a combination of preparative LPSEC and analytical polyacrylamide gel electrophoresis (PAGE), called LPSEC-PAGE, which was for the first time applied to aquatic NOM extracted from rivers and lakes of the U.S. and Finland. , Protein-like fluorescence was found in the highest and medium molecular size fractions, while humic-like fluorescence was detected mostly in the low molecular size fraction.…”