Identification and analysis of polymer additives using packed-column supercritical fluid chromatography with APCI mass spectrometric detection

Abstract

Packed-column supercritical fluid chromatography (pSFC) with detection using atmospheric pressure chemical ionisation (APCI) mass spectrometry (MS) provides a versatile method for the detection and quantification of 20 polymer additives, including common antioxidants, light stabilisers and slip agents. Using MS with APCI in both positive and negative ion modes both molecular mass data and informative fragmentation patterns were obtained. The pSFC-MS technique was shown to be linear over a wide concentration range (0.05–25 µg ml^–1) and picogram limits of detection with positive ion APCI (single ion monitoring) were determined for Tinuvin 327 (68 pg) and Irganox 1010 (390 pg). The corresponding figures for negative ion APCI were 150 and 470 pg, respectively. Standard mixtures of additives could be separated in less than 15 min with a high degree of resolution. Experiments on additives extracted from polyethylene confirmed these observations, and it was possible not only to identify a number of the additives, but also, in the case of the antioxidant Irgafos 168, an oxidation product.