In a significant advance in understanding the environmental behaviour of pollutants, researchers from the University of São Paulo have developed a novel analytical approach to investigate the interactions between humic substances and a variety of contaminants, including herbicides and emerging pollutants. Published in the journal Analytica Chimica Acta on January 16, 2024, the study outlines the use of porous polymer monolithic columns for affinity chromatography as a simpler and more efficient alternative to traditional methods.
The interaction of humic substances with pollutants is a critical factor in predicting how these chemicals will move through the environment, how available they are to living organisms, and how quickly they will degrade. Humic substances, which are a complex mixture of organic materials found in soil and water, have the potential to bind with pollutants, affecting their fate and transport in the environment.
Typically, the study of interactions between humic acids and pollutants has relied on various techniques such as fluorescence and UV-vis spectroscopy, equilibrium dialysis, and solid-phase extraction coupled with liquid chromatography-mass spectrometry. These methods are often cumbersome and require large sample volumes, extended equilibration periods, and elaborate extraction procedures that can introduce analytical errors.
The new approach, pioneered by researchers Fernando H. do Nascimento and Jorge C. Masini at the University of São Paulo, leverages monolithic high-performance affinity chromatography and demonstrates its effectiveness in determining binding constants between humic acids and various pollutants. The team utilized polymer monoliths made from aminated glycidyl methacrylate and ethylene glycol dimethacrylate to anchor Cu(II) ions, which subsequently fixated humic acid to create an active interaction phase for the chromatography columns.
Approximately 86.5 mg of humic acid was immobilized per gram of polymer, enabling the investigation of the binding strength between humic acid and various contaminants at a controlled temperature of 25 °C and a pH of 6.0 ± 0.1. Surprisingly, some common drugs like paracetamol, acetylsalicylic acid, and salicylic acid exhibited no retention. In terms of compounds that did interact with humic acid, the researchers observed an order of increasing affinity, providing valuable insights into how these interactions occur.
This study is hailed as the first to demonstrate the utilization of a monolithic platform for immobilizing supramolecular structures of humic acids. The use of immobilized metal affinity chromatography allows for a comparative evaluation of humic acid’s affinity towards a range of emerging pollutants. This method offers several advantages, including the need for only small quantities of humic acid, which is particularly beneficial when preparing columns with humic substances that have been isolated and purified from remote environments.
The research has profound implications for our understanding of environmental transport mechanisms of pollutants. It allows for a better risk assessment and formulation of strategies to mitigate the impact of these chemicals on ecosystems and human health.
For this cutting-edge study, the research team has put forth a Declaration of Competing Interest, affirming that there are no competing financial interests or personal relationships that could have appeared to influence the work reported in the paper.
The study’s DOI is 10.1016/j.aca.2023.342183, and the reference number is S0003-2670(23)01404-6. The article, part of the journal Analytica Chimica Acta, volume 1288, was published online on January 16, 2024.
References
1. Nascimento, F. H. & Masini, J. C. (2024). Porous polymer monolithic columns to investigate the interaction of humic substances with herbicides and emerging pollutants by affinity chromatography. Analytica Chimica Acta, 1288. DOI: 10.1016/j.aca.2023.342183.
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4. Simpson, A. J. (2002). Determining the molecular weight, aggregation, structures and interactions of natural organic matter components using diffusion ordered spectroscopy. Chemosphere, 48(9), 997-1008.
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Keywords
1. Affinity chromatography humic substances
2. Soil pollutant binding study
3. Emerging contaminants interaction
4. Herbicide environmental transport
5. Analytical chemistry environmental pollutants