Microplastic pollution is globally widespread; however, the presence of microplastics in soil systems is poorly understood, due to the complexity of soils and a lack of standardised extraction methods. Two commonly used extraction methods were optimised and compared for the extraction of low-density (polyethylene (PE)) and high-density microplastics (polyethylene (PET)), olive-oil-based extraction, and density separation with zinc chloride (ZnCl2). Comparable recoveries in a low-organic-matter matrix (soil; most >98%) were observed, but in a high-organic-matter matrix (compost), density separation yielded higher recoveries (98 ± 4% vs. 80 ± 11%). Density separation was further tested for the extraction of five microplastic polymers spiked at different concentrations. Recoveries were >93% for both soil and compost, with no differences between matrices and individual polymers. Reduction in levels of organic matter in compost was tested before and after extraction, as well as combined. Double oxidation (Fenton’s reagent and 1 M NaOH) exhibited the highest reduction in organic matter. Extracted microplastic polymers were further identified via headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME–GC–MS). This method has shown the potential for descriptive quantification of microplastic polymers. A linear relationship between the number of particles and the signal response was demonstrated for PET, polystyrene (PS), polyvinyl chloride (PVC), and PE (R² > 0.98 in alluvial soil, and R² > 0.80 in compost). The extraction and identification methods were demonstrated on an environmental sample of municipal biowaste compost, with the recovery of 36 ± 9 microplastic particles per 10 g of compost, and the detection of PS and PP.

The uptake and translocation of Pb, Cr, Cd, and Zn in tomato plants (Solanum lycopersicum L. Rally) were investigated. Tomato seedlings were grown for five weeks in pots containing 40 L of Hoagland nutrient solution (pH 7) or contaminated nutrient solutions at two concentration levels for each element: Cr (100 and 1000 ng/mL), Zn (100 and 1000 ng/mL), Pb (100 and 500 ng/mL), and Cd (50 and 500 ng/mL). The solutions were replenished weekly to maintain a volume of 40 L (pH 7), and 10 mL samples were collected for elemental analysis. After five weeks, the plants were harvested and separated into roots, stems, leaves, and fruits. These samples underwent microwave-assisted digestion, and the element concentrations were determined by inductively coupled plasma mass spectrometry (ICP-MS). The results revealed that the elements were mainly accumulated in the roots, with much lower concentrations determined in the fruits. Pb and Cr accumulated only minimally in fruits, with Pb levels of 0.0009 mg/kg wet weight at LI and 0.003 mg/kg wet weight at LII, and Cr levels of 0.028 mg/kg wet weight at LI and 0.031 mg/kg wet weight at LII. The Pb levels did not exceed the permissible limits set by EC regulations (0.05 mg/kg wet weight). Zn exhibited the highest accumulation in fruits, with 2.17 mg/kg wet weight at LI and 4.8 mg/kg wet weight at LII. By contrast, the Cd concentrations in fruits (0.25 mg/kg wet weight at LI and 1.1 mg/kg wet weight at LII) exceeded the EC regulatory limit of 0.02 mg/kg wet weight. The uptake of other essential elements into the tomato plant remained largely unaffected by the presence of contaminants. These results provide valuable insights into food safety. Laser ablation (LA)-ICP-MS imaging revealed an even distribution of Cd and Zn in the leaves of plants grown in contaminated nutrient solutions. By contrast, Cr and Pb were predominantly localized in the leaf veins and at the leaf apex, suggesting different transport mechanisms for these elements from the roots to the aerial parts of the plant.

This study critically evaluates an analytical approach combining enzymatic extraction and single particle ICP-MS (spICP-MS) for quantifying europium-doped polystyrene nanoplastics (Eu-PS-NPs) bioaccumulated in tomato tissues. Optimization of extraction parameters identified citrate buffer at pH 6.5 and a digestion temperature of 37 °C as the most effective extraction conditions, while maintaining particle stability. Experiments with spiked tomato tissues demonstrated that extraction efficiency is highly tissue-specific, with optimal digestion of 24 h for stem, leaf, and fruit, and 36 h for root tissues, and enzyme concentrations ranging from 10 to 100 mg per sample. Under optimized conditions, good extraction recoveries (85 - 116 %) were achieved for particle number and mass concentrations, particle size and mass, and total Eu mass, with the majority of extracted Eu associated with NPs and around 10 % as ionic Eu. In contrast, analysis of tomato samples exposed to Eu-PS-NPs during their growth revealed substantially lower and tissue-dependent extraction recoveries. Root and stem tissues yielded only 18 - 32 % of total Eu mass concentration, while leaves showed recoveries ≤ 21 % under most extraction conditions. Fruit samples exhibited higher apparent recoveries (66 - 80 % after 24 h digestion), likely due to the acidic environment promoting Eu leaching from NPs. Across all exposed tissues, ionic Eu fraction dominates (reaching up to 97 % in fruits), indicating extensive leaching from Eu-PS-NPs in the tomato plants. These findings underscore the importance of accounting for matrix effects, metal leaching, and the limitation of extrapolating recoveries from spiked controls to exposed samples when interpreting spICP-MS data from plant exposure studies with metal-doped NPs.