Microliter-Scale Stereolithography Enables High-Resolution 3D Printing of Functional Extraction Sorbents

Despite the revolutionary potential of 3D printing in the analytical sciences, the large volume resin requirements of conventional stereolithography (SLA) platforms remain a significant barrier to the development of novel materials. This study reports a transformative modification to an SLA 3D printing system that enables the fabrication of small-diameter extraction sorbents using prepolymer volumes as low as 150 μL. The performance of SLA and liquid crystal display (LCD) printers, in terms of printing success rate and the reusability of prepolymer mixtures, was compared in the printing of ionic liquid (IL) and deep eutectic solvent (DES)-based mixtures. The SLA approach provided higher printing success rates across extraction sorbents at varied diameters used as fibers in solid-phase microextraction (SPME). The physicochemical properties of the prints─and their characterization, including the measurement of diameters and masses─as well as thermogravimetric analysis was determined. The resulting polymeric IL fibers were applied to the extraction of 15 analytes, including terpenes, polycyclic aromatic hydrocarbons, and alkylphenols from aqueous samples, followed by direct thermal desorption by gas chromatography-mass spectrometry (GC-MS) analysis. Extraction optimization studies were conducted on the IL content, SPME fiber diameter, and extraction kinetics. Method validation for the extraction of terpenes yielded excellent linearity (R² > 0.967), with limits of detection (LOD) and quantification (LOQ) ranging from 0.05 to 1.3 μg L^-1 and 0.2 to 4 μg L^-1, respectively. Furthermore, statistical analysis of three printed fibers confirmed high fiber-to-fiber reproducibility with no significant differences in extraction efficiency.