Sustainable three-dimensional printed devices for thin-film solid-phase microextraction in green and efficient determination of isoflavones in environmental waters.

This study reports an efficient sample preparation method based on fused filament fabrication (FFF) 3D printing technology for the production of thin-film solid-phase microextraction (TF-SPME) devices, applied to the determination of four isoflavones, daidzein (DA), glycitein (GLY), genistein (GEN), and formononetin (FOR), in water samples. Eleven different filaments were used for fabricating devices to assess their influence on extraction efficiency. In addition to the selection of the printed device, critical parameters, including desorption solvent, desorption and extraction time, sample pH, and salting-out effect were optimized using univariate and multivariate strategies. Among all tested filaments, polyamide 6 (PA6) was identified as the most suitable and selected due to its higher extraction efficiency for all analytes. The extraction step consisted of 1.5 mL of sample, pH adjusted to 6, and 15% of sodium chloride (NaCl), extraction time of 30 min, followed by liquid desorption with 300 μL of methanol (MeOH) and 30 min of desorption time. The analytical parameters of merit of the method were evaluated, showing coefficients of determination (R2) equal to or greater than 0.9930. LODs and LOQs were 1.5 and 5 μg L-1 for all analytes. Precisions were equal to or below 12.3%. Recoveries ranged from 69% to 109% and no matrix effect was observed. Seven water samples collected from different points were analyzed though the method, and the analytes were not detected, or were present at concentrations below the method's LOD. The reusability of the devices was confirmed for up to 10 consecutive uses following a cleaning procedure.