Glyphosate and AMPA passive sampling in freshwater using a microporous polyethylene diffusion sampler

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Environmental Science

Background:

• Glyphosate (PMG) is a widely used herbicide, raising concerns about its environmental persistence.
• Increased monitoring of PMG and its metabolite aminomethyl phosphonic acid (AMPA) in aquatic ecosystems is anticipated.
• There is a need for cost-effective monitoring and risk assessment strategies for these compounds.

Purpose of the Study:

• To evaluate a microporous polyethylene tube (MPT) as a passive sampling device for PMG and AMPA.
• To determine the performance of MPTs under controlled laboratory and in situ freshwater conditions.
• To assess the sensitivity and applicability of MPT passive sampling for herbicide detection.

Main Methods:

• Investigated MPTs (2-mm thickness, 2.5 μm pore size) as diffusive samplers.
• Conducted uptake experiments in the lab (pH 6.8, 6 days) and in a freshwater lake (pH 7.3, 11 days).
• Analyzed sorbed PMG and AMPA levels and calculated sampling rates (Rs).

Main Results:

• MPTs demonstrated low sorption levels (Kmw ≈ 1 mL g⁻¹), validating their use as diffusive layers.
• Linear uptake of PMG and AMPA was observed in laboratory conditions with Rs of 18 and 25 mL d⁻¹, respectively.
• In situ, PMG Rs (28 mL d⁻¹) matched lab results, while AMPA was detected in samplers but below LOQ in water samples, showing enhanced sensitivity.

Conclusions:

• MPTs are effective diffusive layers for passive sampling of PMG and AMPA.
• The developed passive sampling device offers increased sensitivity for detecting herbicides in aquatic environments.
• This method provides a viable, low-cost strategy for future environmental monitoring and risk assessment of PMG and AMPA.