Analysis of Polymer Additives and Impurities by Liquid Chromatography/Mass Spectrometry and Capillary Electrophoresis/Mass Spectrometry

The analysis of polymeric materials can be quite challenging because such samples are often of complex nature due to the presence of various groups of additives, compounding ingredients, and fillers. Of special importance are stabilizers that protect the material from degradation by thermal stress during manufacture or from environmental impact during use. Apart from intact stabilizers, the degradation products of stabilizers should also be identified to understand the reactions occurring in a polymeric material. In all cases, the optimization of performance of a polymer as well as the reduction of production costs requires adequate analytical methods, whereby high-performance liquid chromatography plays a major role. As outlined in this review, mass spectrometry with atmospheric pressure ionization has become state-of-the-art for identification of components in polymeric materials after separation by liquid chromatography. These ionization techniques include electrospray ionization, atmospheric pressure chemical ionization, and atmospheric pressure photoionization. The latter technique shows various advantages such as low detection limits and applicability to a wide range of structurally different polymer additives. Besides chromatography, capillary electrophoresis has demonstrated some potential for separation of polymer stabilizers and for characterization of polymers, but its importance is still limited in comparison with liquid chromatography. As an alternative to the combination of chromatography with mass spectrometric detection, direct mass spectrometric techniques for solid polymer samples are emerging. These techniques provide new tools for quick screening procedures at the same time as avoiding tedious sample preparation.