The production of polymer reference materials for microanalysis with high homogeneity by a 3D printing method

Abstract

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is a powerful tool for the microanalysis of solid materials. Still, one limitation of this method is the lack of well-characterized homogeneous reference materials (RMs). This work proposes a new three-dimensional printing (3DP) method to produce polymer RMs for microanalysis. Cr, Cd, and Pb solutions were gravimetrically doped into polyacrylate resin by mixing with the dispersant and then cured with 3DP techniques. The retention rates of the doped elements were first investigated with the external standard method, and the results showed that they were totally dispersed into the solid materials. Moreover, after further optimization, it was proved that there was no obvious heterogeneity among printed samples. To evaluate the micro-scale homogeneity, the printed samples were analyzed with LA-ICP-MS and simulated line scan mapping was presented in polar or Cartesian coordinates. They still show good homogeneity when the spot size is small to 50 μm, and for Pb, it can be as small as 14 μm. The mass concentration of doped elements was determined by isotope dilution (ID)-ICP-MS and verified to be equivalent to the nominal values. Compared with the traditional methods to produce commercially available polymer CRMs, the 3DP method greatly increased the sample homogeneity and the accuracy of the desired concentration.