A Direct Mass Spectrometry Method for the Rapid Analysis of Ubiquitous Tire-Derived Toxin N-(1,3-Dimethylbutyl)-N′-phenyl-p-phenylenediamine Quinone (6-PPDQ)

Abstract

The oxidative transformation product of a common tire preservative, identified as N-(1,3-dimethylbutyl)-N′-phenyl-pphenylenediamine quinone (6-PPDQ), has recently been found to contribute to "urban runoff mortality syndrome" in Coho salmon at nanogram per liter levels. Given the number of fish-bearing streams with multiple stormwater inputs, large-scale campaigns to identify 6-PPDQ sources and evaluate mitigation strategies will require sensitive, high-throughput analytical methods. We report the development and optimization of a direct sampling tandem mass spectrometry method for semiquantitative 6-PPDQ determinations using a thin polydimethylsiloxane membrane immersion probe. The method requires no sample cleanup steps or chromatographic separations, even in complex, heterogeneous samples. Quantitation is achieved by the method of standard additions, with a detection limit of 8 ng/L and a duty cycle of 15 min/sample. High-throughput screening provides semiquantitative concentrations with similar sensitivity and a full analytical duty cycle of 2.5 min/sample. Preliminary data and performance metrics are reported for 6-PPDQ present in representative environmental and stormwater samples. The method is readily adapted for realtime process monitoring, demonstrated by following the dissolution of 6-PPDQ from tire fragments and subsequent removal in response to added sorbents.

Transformation Products of Tire Rubber Antioxidant 6PPD in Heterogeneous Gas-Phase Ozonation: Identification and Environmental Occurrence

“…Although lack of analytical standards precluded its quantification here, TP 274 merits full characterization. Measured 6PPDQ concentrations in runoff samples (140 ± 60 ng/L) were relatively low; possibly because this roadway was not heavily trafficked, compared with prior reports addressing roadway runoff from Seattle and Los Angeles (54–1300 ng/L), stormwater collected from Canada (35–627 ng/L), , and runoff collected in China (210–2430 ng/L) …”

“…Recently, our group identified 6PPD-quinone (6PPDQ), a highly toxic (LC 50 for coho salmon, white-spotted char, and brook and rainbow trout: 95–1000 ng/L) ozone (O 3 )-derived transformation product of 6PPD ( N -(1,3-dimethylbutyl)- N ′-phenyl- p -phenylenediamine); − 6PPDQ has now been detected globally in water, − dust, − and air samples. − 6PPD is ubiquitously used in tire rubbers as an antioxidant at 0.4–2% by weight, where it is designed to quickly react with ground-level O 3 to protect rubber elastomers. , Such reactions inevitably form other transformation products (TPs) beyond 6PPDQ during the tire rubber lifetime. , For example, early studies on the antioxidant efficacy of 6PPD (e.g., Lattimer et al) proposed several ozonation TPs based on low-resolution mass spectrometry and associated data . Recently, using high-resolution mass spectrometry (HRMS), Klöckner et al identified 6PPD-related chemical features as markers of tire and road wear particles, and Hu et al used gas-phase ozonation experiments to generate candidate feature lists for 6PPD TPs .…”

New Evidence of Rubber-Derived Quinones in Water, Air, and Soil

“…N , N ′-Substituted p -phenylenediamines (PPDs) are manufactured and widely used as antioxidants and antiozonants in the industry for production of tires, belts, hoses, and cables. − The chemicals provide superior capacity for protection of rubber and its products against heat degradation, breaking down, and ozone cracking. ,, However, the vast number of rubber products have resulted in an incredible release of PPDs and related degradation products into the environment. Various PPDs, as indicated in Table , such as N -(1,3-dimethylbutyl)- N ′-phenyl- p -phenylenediamine (6PPD), N , N ′-bis­(1,4-dimethylpentyl)- p -phenylenediamine, N -phenyl- N ′-cyclohexyl- p -phenylenediamine (CPPD), N -isopropyl- N ′-phenyl-1,4-phenylenediamine (IPPD), N , N ′-di­( o -tolyl)- p -phenylenediamine (DTPD), and N , N ′-diphenyl- p -phenylenediamine (DPPD), have been detected in different environmental matrices, including airborne particles, water, and sediments, − which has yielded grave concerns regarding their potential threats to the environment and human health. A study by Prosser et al.…”

The Tire-Derived Chemical 6PPD-quinone Is Lethally Toxic to the White-Spotted Char Salvelinus leucomaenis pluvius but Not to Two Other Salmonid Species

“…Recently, acute mortality of coho salmon ( Oncorhynchus kisutch ) following exposure to urban stormwater runoff was demonstrated to be caused by a transformation product of tire rubber antioxidant N -(1,3-dimethylbutyl)- N ′-phenyl- p -phenylenediamine (6PPD) . The transformation product, 6PPD-quinone (6PPD-Q), is generated by the reaction of 6PPD with atmospheric ozone and has been found worldwide from stormwater runoff, − road dust, − and atmospheric particles. , 6PPD-Q can cause lethality in coho salmon at a 24 h median lethal concentration (LC 50 ) as low as 0.095 μg/L and is also highly toxic to other salmonid species, as demonstrated by a recent study: , rainbow trout ( Oncorhynchus mykiss ) and brook trout ( Salvelinus fontinalis ) with 24 h LC 50 values of <2 μg/L.…”