# Gas Chromatography-Atmospheric Pressure Chemical Ionization (GC-APCI) Expands the Analytical Window for Detection of Large PAHs (≥24 Ringed-Carbons) in Pyroplastics and Other Environmental Matrices

## TL;DR

This study introduces a new method using GC-APCI to detect large PAHs in pyroplastics, which can help identify burnt plastics in environmental samples.

## Contribution

A novel GC-APCI method for detecting large PAHs (≥24 ringed-carbons) in pyroplastics is developed.

## Key findings

- Pyroplastics contain over 100 times more large PAHs than unburnt plastic pellets.
- 1,3,5-triphenylbenzene is identified as a potential chemical marker for pyroplastics.
- The method enables sensitive detection without sample fractionation or cleanup.

## Abstract

Open waste burning,
large-scale fires, and maritime disasters produce
partially burnt plastic called “pyroplastic”. Chemical
markers would provide a complementary method to appearance and physical
properties for identifying pyroplastics in environmental samples,
particularly with respect to microplastics. Pyroplastic can contain
significant quantities and unique distributions of parent polycyclic
aromatic hydrocarbons (PAHs) with molecular weights up to 278 Da.
Because of this enrichment, we considered whether large PAHs (≥24
ringed-carbons) could serve as chemical markers for pyroplastics.
To address this, we developed a high-temperature method for gas chromatography
atmospheric pressure chemical ionization (GC-APCI) coupled with tandem
mass spectrometry (MS/MS) to target large PAHs with molecular weights
ranging from 314–424 Da. Method development was performed using
National Institute of Standards and Technology standard reference
materials (SRMs) previously characterized for PAHs greater than 302
Da. A PAH class-specific MS/MS acquisition scheme combined with a
simple, generic microextraction provided sensitive and specific detection
without the need for sample fractionation or cleanup. Pyroplastics
collected during the 2021 M/V X-Press Pearl ship
fire and plastic spill were analyzed. A semiquantitative comparison
showed that the pyroplastic samples contained over 2 orders of magnitude
more of the 16 large PAHs (314–424 Da) than unburnt plastic
pellets, reflecting previously observed trends for parent PAHs up
to 278 Da. Qualitative comparison of samples and SRMs revealed multiple
potential candidates (including 1,3,5-triphenylbenzene) suitable for
further study as markers of pyroplastics in complex environmental
samples. A suite of chemical markers for pyroplastics should prove
helpful in monitoring efforts for air quality, waste management, microplastic
pollution, and fires at the forest–urban interface.