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.

中文翻译：

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通过单粒子 ICP-MS/MS 表征萝卜 (Raphanus sativus L.) 中的 TiO2 NP

二氧化钛纳米粒子 (TiO2 NPs) 越来越多地用于广泛的消费品和工业应用中，导致它们存在于环境中，在那里它们可以与包括可食用植物在内的植物相互作用。此外，释放的 TiO2 NPs 会发生化学和物理转变，这可能会影响它们的潜在毒性。然而，通过提供最高灵敏度的 ICP-MS 技术研究环境样品中的 TiO2 NP 受到一些元素（例如，植物组织中丰富的 Ca）的存在的阻碍，这些元素会导致多原子和/或同量异位素干扰. 本研究首次提出使用串联质谱和单粒子模式 (SP-ICP-MS/MS) 的三重四极杆 ICP 来研究吸收、易位、以及在模型植物（Raphanus sativus L.）中具有两种不同标称尺寸的 TiO2 NPs 的可能转化。仔细优化反应池条件（O2 和 H2 气流）可以降低背景水平并显着提高分析的灵敏度，将超纯水中的 TiO2 NP 的尺寸检测限降低至 15 nm，并且在含有 50 mg L–1 Ca 的基质中为 21 nm。此外，为了从用 TiO2 NPs 处理的植物组织中提取完整的纳米颗粒，应用酶消化程序，然后通过 SP-ICP-MS 进行尺寸表征。在用 TiO2 NPs 处理的根中获得的尺寸分布表明优先吸收较小的纳米颗粒。结果还表明，大多数 TiO2 NPs 保留在根中。此外，