A researcher at UJI puts forward a technique to identify compounds derived from the degradation of pesticides

Pesticides are a highly important environmental problem because of their toxicity and widespread use worldwide, and also because their waste could eventually contaminate various media (soil, water, air, food) that could finally affect the development of life, especially human life. For this reason, the European Union has set very strict limits as regards the amount of waste that can be found in water and food for human consumption. Scientists have, therefore, had to develop very precise analysis techniques in order to detect the hundreds of different pesticides that are used in agriculture.

However, most control programmes for these pollutants only focus on unaltered pesticides, even though several compounds, which are derived from the environmental degradation of these relatively persistent and toxic pesticides (transformation products in scientific jargon), are known This deficit of information on the presence of transformation products in the environment is mainly due to the lack of an analytical method that is able to detect them. María Ibáñez’s work meets this need.

The method consists in combining two already existing chemical analysis techniques: liquid chromatography and mass spectrometry. To check their combined potential, Ibáñez exposed a certain group of pesticides to ultraviolet radiation. In this way, she simulated the effect that sunlight exerts on pesticides in the environment (photodegradation) in the laboratory. The global purpose was to determine which compounds the original phytosanitary product was transformed into. To this end, she combined liquid chromatography and mass spectrometry with quadrupole time–of-flight analysers.

Once the transformation products had been identified under lab conditions, the second part of the study consisted in developing an additional method which would allow to determine the presence or absence of these compounds in the environment, as well as to quantify their levels. To this end, Ibáñez used the same method but she used a triple-quadrupole analyser on this occasion.

After analysing water samples (both surface and underground) taken from various points of the Valencian Community, Ibáñez and her collaborators detected the presence of some of these transformation products.

The study has also allowed us to see the magnitude of the problem generated by the degradation of pesticide waste in soil and water, a facet of the environmental problem of phytosanitary products to which no special attention has been paid to date. “It is worth mentioning that the detection frequency of transformation products, elucidated in relation with intact pesticides, has increased and is, in many cases, higher than the concentration levels in the products themselves”, indicates María Ibáñez in her thesis.

A question that still had to be clarified was whether the new method would be able to also identify transformation products of pesticides in living organisms. Therefore, in vitro experiments with microsomes (cell cultures) and in vivo experiments with rats were conducted in collaboration with UJI’s Department of Psychobiology. Once more, the potential of this technique was evidenced, this time in the field of biology.

“Coupling liquid chromatography with mass spectrometry by using triple-quadrupole and quadrupole time-of-flight analysers has proved to be a powerful analytical tool for the identification, quantification and confirmation of transformation products and pesticide metabolites in environmental and biological samples”, María Ibáñez explains. With her work, Ibáñez opens the way forward to future studies not only on these compounds but, above all, on their effects on human health. And all this thanks to her verification of an analytical method that can detect them and can quantify these compounds.

The study of this researcher at UJI’s Institute of Pesticides and Waters has been directed by Félix Hernández and Juan Vicente Sancho, scientists from this Institute, and has been published in the form of scientific papers in international journals such as Analytical Chemistry, Analytical and Bioanalytical Chemistry, Journal of Chromatography A, Trends in Analytical Chemistry and Rapid Communications in Mass Spectrometry.