Organic matter is ubiquitous in the environment and one of the most important copper complexants.
It is well documented that organic matter in natural environments affects the transport and fate of copper as well as its toxicity. Despite the large volume of literature available on copper binding by organic matter, it is still unclear how the molecular structure and chemical composition of organic matter affect copper binding. The binding mechanism also remains unsolved. In this work, the dependence of the origin of organic matter samples on copper binding is studied using ion-selective electrode titrations. Results from attempts to relate copper binding to differences in chemical structure show that copper binding properties are a function of the source of natural organic matter.