Monitoring pesticides in post-consumer containers by GC/TOFMS and HPLC/DAD after the triple rinse method

ABSTRACT

Plant protection products are commercially available both in solid form and liquid formulation solutions. In Portugal, the volume of pesticides sold in 2019 translates into almost 800 tons of packaging material. Most of these materials are plastic containers, the remainder being mainly cardboard, mixed materials and metal. After use, the containers may still have relatively high amounts of toxic pesticides, which render them hazardous. The triple rinsing practice has been highly suggested to reduce the amount of pesticides in the empty containers, in order to allow further recycling. In Portugal there is an ongoing campaign to encourage the triple rinsing, aiming to make this type of waste non-hazardous. Thus, a way to monitor the concentration of leftover pesticides in the containers is necessary. This work describes the development of a methodology for the determination of 32 pesticides in used containers, and a monitoring campaign carried out between April 2018 and February 2021. The method involves grinding the material to a small particle size (<0.5 mm), followed by ultrasound-assisted liquid extraction with a tetrahydrofuran solution and analysis by GC/TOFMS and HPLC/DAD. The recoveries obtained were between 71–116% for all compounds except captan (62%), triclopyr (40%) and mesotrione (32%). The limits of detection and quantification were between 2.6–53.6 mg/kg for GC/TOFMS and 8.1–162.5 mg/kg for HPLC/DAD. The first three collections of containers (containing several materials from plastic to metal) showed high values for the sum of all analytes (1661 to 4332 mg/kg), whereas the last five collections (only plastic materials) presented a lower content (180 to 521 mg/kg), which reflects the effectiveness of the campaign promoting the triple rinsing practice of plastic containers.

KEYWORDS:

• Empty plant protection products packaging
• triple rinsing
• pesticides
• plastic packaging
• GC/TOFMS
• HPLC/DAD

Acknowledgements

This work was supported by National Funds through FCT – Foundation for Science and Technology under the Ph.D. Grant (FCT)— UI/BD/150867/2021, under the Project CENSE (Center for Environmental and Sustainability Research) and Associate Laboratory for Green Chemistry–LAQV (UID/AMB/04085/2020, UIDB/05183/2020 and UID/QUI/ 50 0 06/2020), and Valorfito scholarship ‘Armando Murta’. This work has received also funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 778,045 and was also anchored by the RESOLUTION LAB, an infrastructure at NOVA School of Science and Technology. The authors would like to thank Cristina Silva Pereira’s group for allowing the use of their CryoMill.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Fundação para a Ciência e Tecnologia (FCT - Foundation for Sciences and Technology) by Ph.D. Grant (FCT)- UI/BD/150867/2021, Project CENSE UID/AMB/04085/2020 and UIDB/05183/2020 and project LAQV@REQUIMTE (UID/QUI/ 50006/2020); This work has received also funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 778045; Armando Murta Scholarship Edition 2019-2020.