Supramolecular interactions of humic acids with organic and inorganic xenobiotics studied by capillary electrophoresis

Methodology based on capillary electrophoresis (CE) to study humic acids (HAs)–xenobiotics interactions is proposed. The interactions of HAs with organic and inorganic xenobiotics like paraquat, diquat, p,p′-DDE, p,p′-DDT, potassium ferrocyanide, potassium ferricyanide, chloride, 4-nitrocatechol and other organic compounds were studied. They were found to be of different kind depending on the structure of the xenobiotic molecule and on its charge (neutral, positive or negative). Ion binding, hydrogen bonding, van der Waals forces, ligand exchange, hydrophobic and hydrophilic adsorption, charge-transfer complexes and sequestration are some of the different mechanisms proposed to bind inorganic and organic compounds to HAs.