Determination of trace elements in polymers using fsLA-ICP-MS with internal standardization by carbon

Abstract

Determination of trace elements in polymers is necessary for environmental research and compliance. The conventional solution-based inductively coupled plasma-mass spectrometry (ICP-MS) technique is time-consuming because it requires sample decomposition; thus, a faster technique such as laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) is highly desired. LA-ICP-MS allows the direct analysis of polymers, which is faster than using solution nebulization ICP-MS. In previous studies, LA-ICP-MS has been applied for the elemental analysis of polymers by calibrating with matrix-matched standard or/and internal standardization. However, the quantitative analysis of polymers containing oxygen and internal standardization using carbon have not been achieved due to the matrix effect. In this study, we report the analysis of 5 different polymers with carbon concentration ranging from 45.620 to 85.543% and containing heteroatoms such as oxygen and chlorine using a femtosecond (fs) LA-ICP-MS with internal standardization by carbon. By the optimization of laser fluence, elemental fractionation between trace elements and carbon was minimized. Trace elements (Cr, Br, Cd, Hg and Pb) in polymer reference materials including, polyethylene, polyester, acrylonitrile butadiene styrene, polyvinyl chloride, and polypropylene, were determined. The coefficients of determination (R²) of the calibration curves were improved from 0.8067–0.9880 without internal standardization to 0.9556–0.9993 with internal standardization by ¹³C. The determined concentrations agreed with the certified value with deviation within 30% via internal standardization by ¹³C. It was observed that internal standardization with ¹³C is effective regardless of the concentration of carbon and heteroatoms in the polymers. These results show that the polymer matrix effect was compensated. Therefore, fsLA-ICP-MS and internal standardization by ¹³C can be used for the determination of Cr, Br, Cd, Hg and Pb in polymers.