Graphene oxide functionalized with hydrophilic ionic liquid as stir bar coating: Sorptive extraction of selected triazines in grape juice samples.

Background: Sample preparation is essential for reducing matrix compound effects, increasing analytical method efficiency, and enhancing the detection of target compounds. Miniaturized techniques are preferred over conventional methods, due to their alignment with green analytical chemistry principles, reducing waste and offering comparable efficiency. The effectiveness of extraction techniques based on the use of sorbents depends on sorbent-analyte interactions, driving the search for more selective and versatile materials. Graphene oxide is noted for its high surface area, conjugated structure, and potential for functionalization, improving its adsorption capacity and modifying its polarity.

Results: In this work, novel sorbents were prepared by functionalizing graphene oxide with two hydrophilic ionic liquids of different structures and evaluated for their extraction capacity for five triazine herbicides. The best hybrid sorbent was used as a coating for homemade stirring bars and applied in the sorptive extraction of five triazines in grape juice samples, combined with determination by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). After optimizing the extraction conditions, the method showed a linear range of 1-50 ng mL for ametryn, atrazine, simazine, and prometryn, and 1-100 ng mL for propazine (r ≥ 0.9955). The limits of quantification in grape juice samples ranged from 0.0015 to 0.0500 ng mL with precision as relative standard deviation (RSD) values less than 15 % and recoveries ranging from 45.3 % to 98.6 %.

Significance: The reported work demonstrates that functionalized graphene oxide with hydrophilic ionic liquids can be successfully used in stir bar sorptive extraction (SBSE) to enhance the efficiency of the method and the sorption of triazines. Additionally, the method uses a low volume of organic solvent, and the fabricated extraction device is low-cost, employs a small amount of sorbent, and is reusable, increasing the analytical frequency for analyzing triazine herbicides in various beverage matrices.