Evaluation of acrylate and epoxy photopolymers used in 3D printing for chemical compatibility with trace atomic spectroscopy applications.

In this study we investigate the chemical purity of prints made by using five different acrylate- and epoxy-based photopolymer resin formulations and two 3D printing technologies (vat photopolymerization (VPP), and material jetting technology (MJT)). In particular, our study focuses on the metallic contaminants present in and/or leachable from these photopolymer resins in view of their trace analytical application, especially as sample preparation/introduction devices in plasma atomic spectroscopy. The effect of the exposure to aqueous media often used in trace analytical sample preparation (10 v/v% HNO3, 10 v/v% H2O2, 10 v/v% ethanol, 10 v/v% acetone and 5 m/v% NaOH) on the liquid uptake, release and degradation was assessed, also as a function of time. The elemental contaminations in the cured resins were investigated by laser-induced breakdown spectroscopy (LIBS) and in the leachates by inductively coupled plasma mass spectrometry (ICP-MS). The effects of reagent exposure to the wettability by water and to the surface chemistry by Raman spectroscopy were also studied. Our results reveal that both the dimensional stability and the compositional homogeneity of these resins are fairly good. Dimensional changes and surface effects were found to be minor and did not cause a significant change in the hydrophilic character. We report concentration data in the leachates for 44 elements which represent most of the frequently measured analytes in trace elemental analysis. Several trace metallic contaminants were detected in the resins, but the leaching/dissolution effect of the liquid reagents were found to only produce less than 100 μg L-1 background concentration levels in the leachate. Only Si and Cl were found to be present in all resins at such high concentrations that prevent the trace analytical measurements of these elements. Our results generally indicate that the purity and chemical resistance of these resins are good enough to produce high-resolution, practical devices that can be effectively used in trace atomic spectroscopy at the ppm (mg/L) or even sub-ppm concentration level, but their purity is not sufficient for ultra-trace analytical use (ppb level or below).