The Problem
For over 20 years, coho salmon populations in Washington State's Puget Sound have suffered unexplained mass die-offs. Some populations are now listed as endangered or threatened. The cause: stormwater runoff from roads carrying 6PPD-Quinone, a transformation product of the tire rubber antioxidant 6PPD that forms when tyres react with ground-level ozone.
6PPD-Quinone is lethal to juvenile coho salmon at concentrations as low as 0.094 ng/mL. Detecting it in tissue at relevant levels demands serious extraction and cleanup chemistry.
The Bigger Picture
Testing for PPD transformation products is growing rapidly. Tyre manufacturers and ecotoxicologists are evaluating alternative p-phenylenediamine compounds (CPPD, 7PPD) as potentially safer substitutes for 6PPD. That means labs need methods that can screen multiple PPD-quinones simultaneously in complex biological matrices.
UCT's Method: QuEChERS Extraction with Multi-Sorbent Cleanup
UCT developed a purpose-built QuEChERS extraction, cleanup, and LC-MS/MS method for multiple PPD-quinones in salmon tissue. The challenge: salmon tissue contains up to 16% fat, heavy carotenoid pigmentation, and co-extractives that suppress ionisation and obscure trace-level analytes.
The Cleanup Strategy
After QuEChERS extraction, samples pass through three UCT push-thru cartridges in series:
- Quick QuEChERS: removes short-chain acids and sugars
- C18: strips carotenoid pigments co-extracted with the tissue
- LipiFiltr: removes stubborn lipids and fats (critical for high-fat salmon matrix)
This layered approach is what gets you from a 16% fat matrix to a clean extract suitable for trace-level quantitation.
Analysis
Extracts are separated on a core-shell C18 HPLC column by LC-MS/MS. 6PPD-Quinone is quantitated using extracted isotope dilution; remaining PPD-quinones use an extracted internal standard. Matrix-matched calibration with LOD/LOQ studies confirms accuracy and precision.
Performance
- Detection limit: 0.073 ng/g (below the lethal threshold for juvenile coho)
- Matrix effects: below 12%
That's sub-lethal sensitivity from one of the fattiest, most pigmented biological matrices you'll encounter in environmental toxicology.
Why Chromatography Direct
The home of chromatography consumables. We carry UCT's full QuEChERS range, push-thru cleanup cartridges (Quick QuEChERS, C18, LipiFiltr), and core-shell analytical columns. High-quality consumables at unrivalled prices, making your lab budget go further.
We're so much more than chromatography. Whether you're testing PPD-quinones in fish tissue, pesticides in food, or emerging contaminants in environmental matrices, we supply the sorbent combinations that deliver clean extracts and defensible data. Talk to us about method-specific cartridge bundles and bulk pricing.
See the application note on our website: Download Application Note
Download the PFAS Solutions Guide