3D printed clear resin stir bar sorptive extraction coupled with high performance liquid chromatography for trace chlorophenols analysis in environmental water samples.

3D printing is an additive manufacturing technology based on digital model files. 3D printing has become a popular manufacturing tool in various fields. Stereolithography offers a series of advantages compared to its counterparts, such as smooth prints, appropriate resolution in all the axes, acceptable organic solvent compatibility and sufficient tightness to the flowing of solutions/solvents at moderate/high pressure. Thus, this work used stereolithography and clear resin (polymethyl methacrylate resin and epoxy resin) to prepare stir bars' coatings, which reduced the size of the fabricated stir bar (1 mm) and no swelling property in organic solvents. In this work, three types of structures were designed as the coatings of stir bars, which were solid, discal, and lattice coatings with equal mass (0.13 g). Because of the largest surface area, lattice coatings were chosen to make clear resin stir bars. The clear resin stir bars were used for stir bar sorptive extraction and combined with high performance liquid chromatography to develop a new method, which was successfully applied to detect four chlorophenols in environmental water samples. Compared with the previous work using melt deposition modeling 3D printing, this work could print hollow structures with higher precision. The stir bars could have higher rotational speed (700 rpm vs 350 rpm), smaller desorption volume (500 μL vs 2 mL), and shorter extraction time (60 min vs 90 min). The stir bars also had excellent mechanical performance and long lifetimes of up to 160 times. LODs of this method were between 0.30 μg/L (2-CP) and 0.97 μg/L (2,4,6-TCP) (S/N = 3), which were below the concentration limits of surface water samples. Relative standard deviations of the stir bars were 1.4-3.9 % (n = 7, c = 10 μg/L).