Development of diffusive gradients in thin-films with mixed binding gels for in situ monitoring of artificial sweeteners in waters

Abstract

The extensive use of artificial sweeteners (ASs) has raised concerns regarding their presence, fate, and detrimental effects in water resources. It is thus of great interest for researchers and regulators to acquire a sensitive, robust, and practical sampling technique for monitoring ASs. In the present study, an effective and established passive sampling method based on the diffusive gradients in thin films (DGT) technique was proposed to measure ASs in water. A mixed binding gel of WAX-XDA1 (3 : 1, w/w) was used for the first time in DGT. The selected mixed binding gel exhibited strong and rapid adsorption of ASs and its total binding capacity was over 20.6 μg per disc. 1% (v/v) ammonium hydroxide-methanol was demonstrated to be an excellent elution solvent for ASs with the elution efficiencies being 80.2–104.9%. The linear accumulation of ASs by WAX-XDA1-DGT matched well with the theoretical values, indicating that the current configuration performs in accordance with the DGT principle. The assembled WAX-XDA1-DGT sampler possessed a good tolerance to a wide range of pH (4–8), ion strength (0–0.5 M), and dissolved organic matter (0–10 mg L⁻¹). In wastewater, comparable or lower DGT-measured concentrations for the ASs were observed compared to the spot sampling results. To the best of our knowledge, no studies have yet been conducted to in situ monitor ASs by using the DGT-based method. This study demonstrates the robustness and reliability of WAX-XDA1-DGT for measuring ASs under a wide range of freshwater circumstances in aquatic environments.