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

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 mu g 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.