Preparation of candidate reference materials for the determination of phosphorus containing flame retardants in styrene-based polymers.

Candidate reference materials (RM) for the analysis of phosphorus-based flame retardants in styrene-based polymers were prepared using a self-made mini-extruder. Due to legal requirements of the current restriction for the use of certain hazardous substances in electrical and electronic equipment, focus now is placed on phosphorus-based flame retardants instead of the brominated kind. Newly developed analytical methods for the first-mentioned substances also require RMs similar to industrial samples for validation and verification purposes. Hence, the prepared candidate RMs contained resorcinol-bis-(diphenyl phosphate), bisphenol A bis(diphenyl phosphate), triphenyl phosphate and triphenyl phosphine oxide as phosphorus-based flame retardants. Blends of polycarbonate and acrylonitrile-co-butadiene-co-styrene as well as blends of high-impact polystyrene and polyphenylene oxide were chosen as carrier polymers. Homogeneity and thermal stability of the candidate RMs were investigated. Results showed that the candidate RMs were comparable to the available industrial materials. Measurements by ICP/OES, FTIR and NMR confirmed the expected concentrations of the flame retardants and proved that analyte loss and degradation, respectively, was below the uncertainty of measurement during the extrusion process. Thus, the candidate RMs were found to be suitable for laboratory use.

Analysis of flame retardants and elements of concern in printed wiring boards with respect to origin and year of construction.

Thirty-one populated printed wiring boards, covering a range of 30 years of construction, and originating from various electronic devices, were investigated using different analytical procedures. Noble, precious and rare metals, as well as environmentally relevant elements were identified by EDXRF, and lead and the flame retardant (FR) indicator bromine were localised by means of microbeam EDXRF. A GC/MS procedure was developed to identify and quantify FR substances. Several sample preparation techniques were applied, optimised and compared. The method of first choice was ultrasonic extraction because it provided the best compromise between effort, cost and quality of the analytical results. Altogether, a wide variety of elements of concern, and halogenated and phosphate-based FRs were found in the investigated boards. Their occurrence is partially related to the origin and/or year of construction.

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.

Versatile and fast gas chromatographic determination of frequently used brominated flame retardants in styrenic polymers.

Two versatile and fast methods to identify and quantify brominated flame retardants (BrFRs) in styrenic polymers were developed. Gas chromatography/mass spectrometry (GC/MS) as well as gas chromatography with electron-capture detection (GC/ECD), both following ultrasonic-supported dissolution and precipitation (USDP), were applied. The substance range includes poly-brominated biphenyls (PBBs) and diphenyl ethers (PBDEs), as well as other commonly used flame retardants (FRs), including two phosphate-based flame retardants. The methods were verified using congener standards and flame-retardant polymer samples. Good recoveries were found. Overall run time for the analysis, including sample preparation, is less than 60 min.

Rapid identification of RoHS-relevant flame retardants from polymer housings by ultrasonic extraction and RP-HPLC/UV.

A rapid method was developed for the extraction and identification of RoHS-relevant organic flame retardants in polymer material. Extraction was carried out using ultrasonic supported solvent extraction (USSE) and isopropanol. HPLC separation was achieved using a reversed-phase phenylhexyl-modified column and methanol, containing 2-aminoethanol-buffered, alkaline water. Identification was carried out by scanning UV detection and comparison with a library assembled from spectra of reference substances. The method was used to extract and identify polymer additives in TV and PC monitor housings. The overall runtime required for extraction and chromatographic analysis is less than 10 min. The limits of detection comply with the recommendations set by the German draft law.

Gas chromatographic determination of phosphate-based flame retardants in styrene-based polymers from waste electrical and electronic equipment.

Two methods for the determination of phosphate-based flame retardants (PFRs) and similar organophosphates (OPs) were developed. Two gas chromatographic systems were applied, one equipped with a quadrupole mass spectrometer (GC/MS), the other with a specific phosphorus-nitrogen detector (GC/PND). A procedure of ultrasonic supported extraction and precipitation (USSE) was applied and verified using in-house produced reference materials. Twelve polymer parts of electrical and electronic devices, and eight polymer references were analysed for their PFR contents. The results show that the methods are capable of identifying PFRs in concentration ranges from 3 µg L(-1) (tricresyl phosphate, TCP) to 12 µg L(-1) (cresyl diphenyl phosphate, CDP) on GC/PND and from 110 µg L(-1) (triphenyl phosphine oxide, TPPO) to 3250 µg L(-1) (tris(ethylhexyl) phosphate, TEHP) on GC/MS in reference solutions. LODs in polymer extracts range from 180 µg g(-1) (triphenyl phosphate, TPP) to 670 µg g(-1) (bisphenol-A-bis(diphenyl phosphate), BDP) on GC/PND and from 75 µg g(-1) (TPPO) to 780 µg g(-1) (BDP) on GC/MS. The overall procedure time for one sample was less than 45 min (GC/MS) and less than 65 min (GC/PND).