Pyrolysis-Gas Chromatography-Mass Spectrometry (Py-GC-MS) Quantification of Tire and Road Wear Particles (TRWP) in Environmental Matrices: Assessing the Importance of Microstructure in Instrument Calibration Protocols

Thermogravimetric methods with internal polymer standards have successfully quantified environmental tire and road wear particle (TRWP) concentrations. However, TRWP quantification in matrices via pyrolysis-gas chromatography-mass spectrometry (py-GC-MS) using butadiene rubber (BR) styrene-butadiene (SBR) marker 4-vinylcyclohexene (4-VCH; 1,4-butadiene-1,4-butadiene dimer) may be uncertain because of variable compositions BR SBR microstructures. To determine if microstructure is contributing to potentially over- or underestimating the environment py-GC-MS analyses, materials (n = 8) commonly found tread varying were py-GC-MS, 4-VCH deuterated standard d-4-VCH provide a response ratio for each polymer. The ratios dimer total quantity (instrument slope) varied up 6.8-fold SBR, reduction 3.6-fold range when was expressed as 1,4-butadiene mass rather than mass. Variability reduced further considering polymerization method emulsion-SBRs 3; 1.4-fold range), but not solution-SBRs 5; 2.7-fold which reflects random versus structured heterosequencing two types, respectively. Our findings suggest that should interpreted based on empirical analysis an appropriate number regionally representative materials, individual rubbers, lack available determining unknown average samples.