Accurate determination of hexabromocyclododecane diastereomers in extruded high-impact polystyrene: Development of an analytical method as a candidate reference method.

Herein, an isotope dilution-liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) method was developed as a candidate reference method for the accurate quantitation of hexabromocyclododecane (HBCDD) diastereomers in plastics. The repeatability, reproducibility, and uncertainty results showed that developed ID-LC/MS/MS method is reliable and reproducible. As homogeneous samples, HBCDD-containing extruded high-impact polystyrene (HIPS) pellets were fabricated via an extrusion process. Notably, we detected α-, β-, γ-, δ-, ε-, η-, and θ-HBCDDs in the extruded HIPS pellets, and then determined their exact mass fractions using the ID-LC-MS/MS method. The relative contents (average ± standard deviation) of HBCDD diastereomers in HIPS obtained using the phenyl-hexyl column were 67.08 ± 0.41% (α-HBCDD), 19.73 ± 0.37% (β-HBCDD), 11.59 ± 0.16% (γ-HBCDD), and 1.6 ± 0.07% (sum of δ-, ε-, η-, and θ-HBCDDs). These values differed significantly from the ones determined for the technical HBCDD mixtures (10.42% α-HBCDD, 5.30% β-HBCDD, 82.13% γ-HBCDD, 2.15% minor HBCDDs) used to fabricate the HIPS pellets and thus demonstrating the HBCDD isomerization during the extrusion. The proportion of minor HBCDDs was smaller than the uncertainty of the total HBCDD and that the sum of α-, β-, and γ-HBCDDs was comparable to the total HBCDD in the investigated samples. Notably, a real-life sample (expanded polystyrene board obtained from a local construction site) also showed a similar HBCDD profile, being rich in α-HBCDD.