Rubber, Plastic and Polymers Overview

The techniques used for the analysis of natural and synthetic polymers and plastics are dependant on the nature of the sample. Products such as polyurethanes, polyesters, acrylics, rubber, polypropylene and polyethylene are usually analysed by Evolved Gas Analysis Mass Spectrometry (EGA-MS) with the solid sample introduced into the instrument via heat desorption. The heating process initially causes desorption of volatile, then semi-volatile, followed by pyrolysis products which are often related to product monomers; each is analysed by the mass spectrometer as it is liberated. Brominated flame retardants and other additives such as antioxidants and plasticisers can also be analysed using this technique, see WEEE & RoHS Analysis.

Leachates and extractables of concern in the pharmaceutical industry are frequently the products of the breakdown of natural or synthetic polymers. These are chemicals released or migrating from the container, closure system or packaging components used in the manufacture, storage or sale of the drug. Typical leachates include elastomers, accelerants, antioxidants, plasticisers e.g. BEHP, phthalates and adipates most of which are amenable to analysis by either EGA-MS, GC-MS or LC-MS.

SGS M-Scan has expanded its capability for analysing polymers to include the analysis of synthetic fabrics and paint laquers using Pyrolysis GC-MS.

The molecular weight distribution of some synthetic polymers is determined by a method developed by SGS M-Scan using Laser Desorption Time-of-Flight Mass Spectrometry (MALDI-TOF MS). The analysis of alkoxylated additives in gasoline has been carried out with this technique as well as by liquid chromatography with electrospray mass spectrometry (LC-MS).

Odours from plastics are analysed by Headspace GC-MS and the results compared with known odour levels from SGS M-Scan's extensive proprietary list of odour thresholds.