Dissolved organic carbon (DOC) is one of the most important
quality parameters in water analysis today. In this connection,
humic substances (HS) play an important role because the major
portion of DOC in natural aquatic systems originates from HS.
HS show polyfunctional structures, which enables these compounds
to interact either with inorganic (e.g., heavy metals) or
organic substances (e.g., pesticides).1 The formation of heavy
metal complexes with HS strongly influences the mobility and
bioavailability of these metals in the environment. It is, therefore,
of great importance that reliable analytical methods are available
for DOC determinations in bulk samples but also for quantification
in chromatographic fractions of compounds which interact with
HS.