Multidimensional gas chromatography approach to measure aroma compounds in post-consumer recycled plastic materials

A sensory‑directed analytical workflow is introduced for the characterisation of extractable aroma‑active non‑intentionally added substances in post‑consumer recycled (PCR) plastic materials. Aroma extract dilution analysis (AEDA) was adapted for solid samples through stepwise reduction of sample mass, enabling determination of flavour dilution (FD) factors without altering injector split conditions or introducing solvent effects. The approach was tested using washed polyethylene fabric softener packaging, for which 30 odour‑active regions were detected by gas chromatography-mass spectrometry-olfactometry (HS‑SPME‑GC-MS-O), including two regions with FD > 2048. Application to recycled plastics revealed distinct aroma profiles across high‑density polyethylene (HDPE), low‑density polyethylene (LDPE) and polypropylene (PP) pellets. GC-MS-O detected 28, 6 and 17 odour‑active regions in HDPE, LDPE and PP, respectively. Subsequent use of heart‑cut multidimensional GC (HS-SPME-MDGC-MS-O) resolved coeluted compounds and increased the number of detectable odorants to 36 in HDPE, 11 in LDPE and 21 in PP, with maximum FD factors of > 256, 2 and 8, respectively. Twenty‑five odorants in HDPE were positively identified using combined mass spectral matching, linear retention indices, and odour descriptors. The results demonstrate that integration of AEDA with MDGC-MS-O provides both enhanced chromatographic resolution and quantitative sensory prioritisation, offering a robust framework for assessing aroma‑active contaminants in recycled plastics intended for food‑contact and other high‑value applications.