Characterization of the micro and nano plastics in foods and food packages and determination of their interaction with vitamins

Micro(nano)plastics act as carriers of various inorganic and organic compounds in different environments, exerting potential effects on both environmental and human health. In recent years, numerous studies have investigated the sorption of various organic compounds-including antibiotics-onto micro(nano)plastics. However, despite the critical biological and ecological roles of vitamins across ecosystems, ranging from humans to plants, the sorption of vitamins onto micro(nano)plastics has remained largely unexplored. In this context, the interaction of micro(nano)plastics derived from food packaging with vitamins B1, B2, B6, and C was examined in both pH-controlled environments and simulated intestinal, gastric, and oral digestive fluids. Sorption behaviors, including kinetic and isotherm models, were evaluated using the batch technique in combination with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Furthermore, spectroscopic techniques such as attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), RAMAN spectroscopy, and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) were employed to characterize sorption in both controlled and simulated digestive environments. Overall, higher sorption capacities were observed under controlled conditions, with environmental pH significantly affecting both sorption efficiency and vitamin stability. While B-group vitamins exhibited higher sorption capacities under neutral pH, vitamin C showed maximum sorption under acidic conditions. The results demonstrated that maximum sorption capacity and time varied depending on the polymer type, vitamin type, and the specific digestive environment (oral, gastric, or intestinal). In the scope of this study, sorption processes between PE, PP, PS, and PET micro(nano)plastics and the selected vitamins (B1, B2, B6, and C) were quantitatively assessed under both controlled and simulated digestive fluid conditions. In controlled conditions, B6 vitamin exhibited the highest sorption capacity, reaching 270.0 µg/g on PE and 256.0 µg/g on PP. For B2 vitamin, sorption capacities were observed as 112.5 µg/g on PE and 24.8 µg/g on PS. Under simulated digestive conditions, B1 vitamin showed a capacity of 100.2 µg/g on PS in gastric fluid and 110.1 µg/g on PE in intestinal fluid. B2 vitamin showed capacities of 217.1 µg/g on PET and 217.0 µg/g on PS in the intestinal environment. B6 vitamin displayed sorption values of 86.2 µg/g on PE and PP in oral fluid, and 82.0 µg/g on PE in intestinal fluid. The results were obtained for vitamin C, which exhibited very high sorption capacities in oral fluid, reaching 867.0 µg/g on PE, 874.2 µg/g on PP, and 817.5 µg/g on PET. These findings highlight the critical influence of pH and environmental conditions on micro(nano)plastic-vitamin interactions and indicate that vitamins like C, which are more stable under acidic conditions, tend to bind more effectively to plastic surfaces. To better understand the interaction mechanisms between vitamins and micro(nano)plastics, kinetic and isotherm modeling approaches were applied. Pseudo-first-order (PFO) and pseudo-second-order (PSO) models were used for kinetic evaluation, while Langmuir and Freundlich models were employed for sorption isotherms. The suitability of each model was determined based on the calculated correlation coefficient (R²) values.