Preparation of reference materials for the determination of RoHS-relevant flame retardants in styrenic polymers.

Reference materials for the analysis of polybrominated diphenyl ethers, polybrominated biphenyls and other common brominated flame retardants (FR) in styrenic polymers were prepared to suit the demands of actual restriction of the use of certain hazardous substances in electrical and electronic equipment analytics. Three methods of preparation were employed, viz. pellet forming, dissolution/vaporisation and extrusion, whereby extrusion proved to be the most suitable method. For extrusion, three procedures of pre-mixing were investigated: the polymers were either mixed with FR powder, FR solutions or FR concentrates that were taken from waste industrial polymers. The latter procedure proved to be most appropriate in terms of analyte concentration, predictability and recovery. The homogeneity of the samples, as well as the chemical and thermal long-term stabilities, was investigated. The result was an optimised method to prepare a suitable reference material for laboratory use.