Quantification of Nanoplastic Uptake in Cucumber Plants by Pyrolysis Gas Chromatography/Mass Spectrometry

Nanoplastic uptake in plants has drawn increasing attention for its potential toxicity to organisms at higher trophic levels. However, the mechanisms remain ambiguous due to the lack of quantitative methods for nanoplastic uptake in plants. Herein, a novel procedure incorporating alkaline digestion, cellulose precipitation, and ultrasonic leaching, followed by pyrolysis gas chromatography–mass spectrometry (Py-GC/MS) analysis, was developed to quantify nanoplastic uptake in plants with cucumber (Cucumis sativus) as the model species. Recoveries of 81.6%–97.2% were obtained for polystyrene (PS) and poly(methyl methacrylate) (PMMA) nanoplastics at spiking levels of 34.5–61.5 μg/g in quality control samples. Detection limits of 2.31–4.15 μg/g for PS and 3.87–8.20 μg/g for PMMA nanoplastics were achieved. After exposure to 50 mg/L of 100 nm PS nanoplastics for 7 and 14 days, 0–6893 μg/g nanoplastics were detected in various dried cucumber tissues using the developed method with their presence identified by scanning electron microscopy (SEM), suggesting nanoplastic uptake, translocation, and accumulation in plants. Comparative experiments with inductively coupled plasma mass spectrometry (ICP-MS) using palladium-labeled nanoplastics further confirmed the promising application of our method in quantifying nanoplastic uptake in plants. Consequently, the proposed method provides new possibilities for screening nanoplastics in plants.