Exploring the Environmental Impact of Tire-Derived Materials Using LC-MS/MS

In this insightful interview, David Oliva, General Manager of Organomation, sits down with Jonathan Navarro Ramos, a PhD student at the University at Buffalo, to discuss his cutting-edge research on environmental pollutants. Jonathan shares his journey in developing methods to detect tire-derived chemicals like 6PPD and 6PPD-quinone in stormwater runoff and highlights the importance of non-target analysis using high-resolution mass spectrometry (HRMS).

Key Topics Covered:

• Research on 6PPD and its transformation into 6PPD-quinone
• Environmental and public health concerns surrounding tire-derived chemicals
• The use of LC-MS/MS in detecting pollutants in challenging matrices
• Sample preparation techniques, including solid-phase extraction and nitrogen blowdown with the Organomation N-EVAP
• Future research directions involving the chlorination of pollutants in wastewater treatment

Learn More: Jonathan also shares surprising findings from his study and emphasizes the global ubiquity of tire-derived pollutants. Don't miss this engaging discussion!

Video Transcription

Overview

• Jonathan’s lab develops methods to detect and quantify environmental pollutants across water, soil, food, and tissues (e.g., fish).
• His current projects center on tire-derived chemicals in stormwater runoff, plus HRMS non-target screening to discover transformation products of tire additives.

Why 6PPD and 6PPD-quinone matter

• 6PPD: an antioxidant widely used in tires and rubber goods to prevent cracking and extend service life.
• Transformation: 6PPD oxidizes to 6PPD-quinone (6PPD-q), now found ubiquitously in the environment (global reports).
• Exposure pathways: Deployment of end-of-life tires in playgrounds, track surfaces, gardening, turf, etc., raises concern about leaching and transport to receiving waters.
• Health & ecology: Interest spans wildlife toxicity and public health; studies have detected 6PPD and 6PPD-q in human urine.

Broader chemical scope

• Beyond 6PPD/6PPD-q, Jonathan’s team evaluates PAHs, phthalates (plasticizers), and metals associated with tire materials—aiming for a comprehensive risk picture.

Why LC–MS/MS?

• Analyte properties: Many TDCs are non-volatile and thermally labile—poor candidates for GC.
• LC separation: Compounds are hydrophilic, well-suited for LC.
• Triple quadrupole (MS/MS): Provides high selectivity and sensitivity (down to low ppb / high ppt), ideal for trace-level environmental measurements.
• Bottom line: LC–MS/MS was the best fit among available techniques on campus.

Sample preparation & main challenges

• Matrices tested included TDA (tire-derived aggregate) and crumb rubber leachates—both highly colored and matrix-rich.
• Workflow (for leachates):
  1. Filtration to remove particulates.
  2. Solid-phase extraction (SPE) to isolate targets.
  3. Nitrogen blowdown to concentrate eluates (then reconstitution in LC mobile phase with internal standards).
• Challenge: Concentration step co-concentrates matrix, elevating background and potentially raising detection limits. This was most pronounced for TDA and crumb rubber extracts.

Nitrogen blowdown equipment

• The lab used Organomation N-EVAP systems for blowdown:
  • Adjustable nitrogen flow control (from gentle to higher flow).
  • Reported as reliable and durable in long-term, routine operation.

Notable findings

• 6PPD detected > 6PPD-quinone in several leachates—contrary to expectation, since 6PPD-q is a primary oxidation product.
• High 6PPD levels observed particularly in TDA and rubber mulch leachates.
• No 6PPD detected in tire-modified asphalt and RMA (another rubber mulch/asphalt category) in this study.
• Implication: Consider limiting use of TDA and rubber mulch where environmental release is likely, pending further risk assessment.

Where the research is heading

• Wastewater treatment angle: Evidence suggests 6PPD and 6PPD-q reach wastewater treatment plants (WWTPs) and exit in effluents.
• Chlorination at WWTPs may generate disinfection byproducts from these compounds—unknowns with potential toxicity.
• Next steps include identifying chlorinated transformation products and evaluating their toxicity in receiving waters.

Takeaway

Jonathan’s work underscores the value of LC–MS/MS for trace detection of tire-derived chemicals across challenging matrices and reveals unexpected persistence of 6PPD in certain recycled tire materials. Ongoing efforts target WWTP transformation chemistry and ecotoxicological relevance, informing policy and material-use decisions around tire-derived products.

This text has been automatically transcribed from a video presentation using AI technology. It may contain inaccuracies and is not guaranteed to be 100% correct.

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