In recent years, the increasing use of zinc oxide nanoparticles (ZnO NPs) in many consumer products and industrial applications made them a new potential source of zinc in the environment. After their release into the environment, ZnO NPs can undergo different transformations which are still poorly understood and may influence their potential toxicity. This study investigates for the first time the fate of zinc, supplied in the form of ZnO NPs and ZnCl₂, taken up by a model edible plant (lettuce, Lactuca sativa L.) by means of different mass spectrometry techniques. Single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) analysis showed the rapid dissolution of ZnO NPs in the growth medium used for cultivation of lettuce, confirming that only dissolved zinc, not intact NPs, is taken up by plants. Taking into account that the beneficial or toxic effects of zinc depend on its form accumulated by plants, it is crucial to identify the chemical forms of zinc and their distribution in edible plant tissues. Therefore, the second part of this work was focused on the study of zinc speciation in plants cultivated with ZnCl₂ by using hyphenated techniques. The proposed approach based on two-dimensional chromatographic (size exclusion – SEC and hydrophilic interaction – HILIC) separation with parallel ICP-MS and ESI-qTOF-MS/ESI-FT-Orbitrap-MS detection allows the determination and identification of minor zinc complexes at environmentally relevant concentrations. Nicotianamine (NA) is shown to be the major ligand binding zinc in lettuce leaves, and the Zn–NA complex is responsible for more than 70% of the total zinc content extracted from lettuce leaves by means of ammonium acetate buffer.

The aim of the study was to concentrate on developing new solvents for extraction of selected metal complexes from young barley. Estimation of the amount of elements in compound, not only their total concentration, is very important because only a part from total content of metal is absorbed by human organism. At the beginning, the total amount of elements in young barley was established as 16.69 ± 0.22 μg g⁻¹ (RSD 1.36%) for copper, 156.29 ± 0.82 μg g⁻¹ (RSD 0.52%) for manganese, 155.35 ± 1.29 μg g⁻¹ (RSD 0.83%) for zinc, 9.10 ± 0.21 μg g⁻¹ (RSD 2.36%) for molybdenum, and 0.35 ± 0.01 μg g⁻¹ (RSD 1.63%) for cobalt. The LOD of analyzed elements were as follows (μg L⁻¹): Mn 0.59, Co 0.05, Cu 0.33, Zn 1.2, and Mo 0.12. The LOQ of studied metals were as follows (μg L⁻¹): Mn 1.9, Co 0.18, Cu 1.1, Zn 4.0, and Mo 1.4. After that, the most suitable solvents were identified. The determination of total and extractable amount of metals in young barley was carried out by standalone inductively coupled plasma mass spectrometry (ICP-MS). In addition, a complementary analysis of extracted metal complexes was performed using size exclusion chromatography coupled with inductively coupled plasma mass spectrometry (SEC-ICP-MS) method. It was confirmed that the natural deep eutectic solvents (NADES) are able to extract different metal and metal species in comparison with commonly used solvents. The study indicated that extraction by using the NADES has been successfully applied for determination of metals and metal complexes in young barley.

Titanium dioxide nanoparticles (TiO₂ NPs) are increasingly used in a wide range of consumer products and industrial applications, causing their presence in the environment, where they can interact with plants including edible ones. In addition, the released TiO₂ NPs can undergo chemical and physical transformations, which may influence their potential toxicity. However, the study of TiO₂ NPs in environmental samples by the technique offering the highest sensitivity, ICP-MS, is hampered by the presence of some elements (such as, e.g., Ca abundant in plant tissues) that cause polyatomic and/or isobaric interferences. This study proposed, for the first time, the use of a triple-quadrupole ICP operating in tandem mass spectrometry and single-particle mode (SP-ICP-QQQ-MS) to study the uptake, translocation, and possible transformations of TiO₂ NPs with two different nominal sizes in a model plant (Raphanus sativus L.). A careful optimization of the reaction cell conditions (O₂ and H₂ gas flows) allowed the reduction in background level and resulted in a significant increase in the sensitivity of the analysis, bringing size detection limits for TiO₂ NPs down to 15 nm in ultrapure water and to 21 nm in a matrix containing 50 mg L^–1 of Ca. In addition, an enzymatic digestion procedure was applied in order to extract intact nanoparticles from the tissues of plants treated with TiO₂ NPs, followed by size characterization by SP-ICP-MS. The size distributions obtained in roots treated with TiO₂ NPs suggested a preferential uptake of smaller nanoparticles. Results also revealed that the majority of TiO₂ NPs were retained in roots. Additionally, no significant dissolution was observed, as well as no differences for nanoparticles found in roots and leaves, proving that radish is able to translocate intact TiO₂ NPs up to aboveground organs.