Development of a Property-Guided HS-SPME-GC-MS Method for Broad-Range Qualitative Screening of Potentially Hazardous VOCs in Recycled Polypropylene

Abstract

The increasing use of recycled plastics has raised concerns regarding the potential emission of hazardous volatile organic compounds (VOCs) during recycling and in subsequent applications. However, systematic analytical methods for VOC analysis in real recycled plastic materials remain limited due to the complex and diverse composition of emitted VOCs. In this study, a qualitative analytical method based on headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME-GC-MS) was developed for characterizing potentially hazardous VOCs in recycled polypropylene (rPP). A total of 622 candidate contaminants associated with recycled plastics were compiled. After screening by NFPA health hazard rating and volatility, 274 potentially hazardous VOCs were retained, and 27 representative compounds were selected to cover broad vapor-pressure and polarity ranges. Five SPME fiber coatings were evaluated, among which DVB/C-WR/PDMS provided the broadest detection coverage, detecting 24 of the 27 representative compounds. Response surface methodology based on rotatable central composite designs was then used to optimize SPME temperature, incubation time, and extraction time. SPME temperature was the dominant factor affecting extraction efficiency, and that vapor pressure was the primary physicochemical determinant of extraction behavior. High- and medium-vapor-pressure VOCs were most efficiently extracted under relatively moderate-temperature conditions, with an optimized SPME temperature of 68.7 °C, incubation time of 5.5 min, and extraction time of 10.4 min. In contrast, low-vapor-pressure VOCs required higher temperatures to promote transfer from the polymer matrix to the headspace, and 110 °C was identified as a practical compromise. Using the optimized method, aliphatic hydrocarbons, aromatic hydrocarbons, oxygenated compounds, and lindane were detected in industrial rPP samples, indicating multiple potential contamination sources in recycled plastic streams. This study provides a systematic HS-SPME-GC-MS strategy for broad qualitative screening of potentially hazardous VOCs in rPP and may support quality control, emission assessment, and process optimization in plastic recycling.