The Invisible Threat from Your Microwave: Real-Time Warning of VOCs Emissions and Rapid Detection of Nanoplastics from Polypropylene Food Containers

Polypropylene (PP) is widely used in microwavable food containers, but the simultaneous release of volatile organic compounds (VOCs) and nanoplastics (NPs) during microwave heating is poorly understood. In this work, we developed two mass spectrometry techniques: low-pressure assisted microwave plasma ionization time-of-flight mass spectrometry (LAMP-TOFMS) for the real-time monitoring of VOC emissions and argon-assisted internal-tube sampling enhanced microwave plasma ionization linear ion trap mass spectrometry (AIS-EMPI-LTQMS) for the rapid, pretreatment-free detection of NPs. Simultaneous monitoring of the representative VOCs styrene and 2-methylpentane revealed dynamic release profiles characterized by a time-dependent increase. The concentrations of styrene and 2-methylpentane from the rectangular plastic container were measured at 3.99 ± 0.65 and 4.43 ± 0.19 ppbv after 180 s of microwave heating. Meanwhile, the AIS-EMPI-LTQMS exhibited a satisfactory analytical performance for PP NPs. The linear correlation ( R 2 = 0.989) was observed between the characteristic ion intensity and the PP NPs concentration. Additionally, our findings highlight container geometry as a significant factor affecting NPs release, with rectangular containers generating the highest PP NPs concentration, up to 2.04 ± 0.32 μg/L under 180 s of microwave heating. This study offers a comprehensive, real-time evaluation of dual pollutants from PP containers and establishes a practical, concise analytical platform for the rapid safety evaluation of food-contact materials.