Evaluation of thermoplastic filaments to construct a disposable 3D printed platform for atomic absorption spectrometry

Additive manufacturing (AM) is gaining considerable interest due to the inherent capacity of fast and low-cost prototyping of customized devices and parts. In this work, seventeen commercial thermoplastic polymer filaments (PLA, TPU, and ABS) and one PLA pellet for fused deposition modeling (FDM) were characterized and evaluated to develop a disposable sample holder to be used as a solid sampling platform in graphite furnace atomic absorption spectroscopy (GFAAS). For GFAAS application, the selection of polymer filaments took into account no or minimal mass residue, decomposition profile, the lowest thermal decomposition temperatures, and colorless filament (preferably). These conditions are essential for the rapid and complete elimination of polymeric matrix without generating residues inside the graphite tube atomizer and lower analytical blanks. Thus, the filaments and pellets were characterized by thermogravimetry, derivative thermogravimetry, differential thermal analysis, differential scanning calorimetry, Fourier-transform infrared spectroscopy and scanning electron microscopy/energy-dispersive X-ray spectroscopy. It is desirable that the sample holder can be entirely decomposed at the lowest possible temperature. The PLA pellet material was chosen because it presented glass transition 71.7 degrees C, melting temperature at 182.7 degrees C, and showed single decomposition step in the 245-325 degrees C range (with peak temperature at 304.4 degrees C), without generating mass residue. The printed sample holder was tested in a commercial spectrometer. As proof-of-concept, the calibration curve for cobalt (0-9.0 ng) was built up with a correlation coefficient of 0.9987. The RSD was < 10%, and the quantification limit was 1.18 ng. Recoveries of Co added to water samples varied from 96-102%.

Automated summary

Additive manufacturing is being widely explored for its fast and low-cost prototyping abilities, with PLA pellets showing promising potential in developing a disposable sample holder for graphite furnace atomic absorption spectroscopy. The selection of polymer filaments was based on various factors to ensure minimal residue and efficient decomposition. Through thorough characterization using different techniques, it was found that the PLA pellet material exhibited favorable thermal properties and performance in analytical testing, demonstrating high precision in cobalt analysis.