Inhalable micro(nano)plastics (MNPs) have emerged as a significant global concern due to their abundance and persistence in the atmosphere. Despite a growing body of literature addressing the analytical requirements of airborne MNPs, the issue of inhalable fractions and analysis of slotted substrates remains unclear. Therefore, the objective of this study is to perform a systematic particle-based analysis and characterization of inhalable microplastics (MPs) collected by a high-volume sampler equipped with a five-stage cascade impactor with a size range of 10 μm to <0.49 μm. The efficacy of collection substrates (Teflon and aluminum) was evaluated, as was the impact of particle transfer from the slotted filters on the analysis area and pretreatment methods including chemical digestion for further analysis. The distribution of MNP particles across different slots of a Teflon filter was investigated using Raman microspectrometry to select an appropriate subsample. The results showed the suitability of Teflon filters without any pretreatment for particles down to a single micrometer. As observed by the SEM/EDX analysis, the airborne particles collected in a filter with a submicrometer range (<0.95 μm) showed a decrease in carbon-rich components compared to those stages with higher cutoff sizes. A minimum of 20 particles were analyzed per 1 cm² of the slotted filter using Raman spectrometry, which revealed a homogeneous distribution of MPs across different slots and yielded a concentration of 452 ± 134 MP/m³ in the first stage of the cascade sampler. The detected MPs were morphologically classified into two main groups: fragments with a size range of 2.8–24.8 μm and fibers with a size range of 28.6–212 μm. Subsequently, the particles were chemically identified as carbon black (tires) and polypropylene. In conclusion, particle-based analysis of size-segregated airborne MNPs presents certain challenges when attempting to analyze particles as small as a single micrometer due to the fact that the aerodynamic diameter of the particles in question and the corresponding analytical limitations that result from this become particularly problematic, especially for cutoffs smaller than 3 μm.

中文翻译：

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使用显微镜、SEM/EDX 和拉曼光谱对粒度分级样品中空气中的微（纳米）塑料进行基于颗粒的分析挑战和策略


可吸入微（纳米）塑料 （MNP） 因其在大气中的丰富性和持久性而成为全球关注的重大问题。尽管越来越多的文献解决了空气中 MNP 的分析要求，但可吸入部分和开槽底物分析的问题仍不清楚。因此，本研究的目的是对配备尺寸范围为 10 μm 至 <0.49 μm 的五级级联接触器的大容量采样器收集的可吸入微塑料 （MP） 进行基于颗粒的系统分析和表征。评估了收集底物（特氟龙和铝）的功效，以及从开槽过滤器转移的颗粒对分析区域和预处理方法（包括化学消解以供进一步分析）的影响。使用拉曼显微光谱法研究 MNP 颗粒在 Teflon 过滤器不同槽中的分布，以选择合适的子样品。结果表明，特氟龙过滤器适用于无需任何预处理即可处理小至单微米的颗粒。通过 SEM/EDX 分析观察到，与截留尺寸较高的阶段相比，在亚微米范围 （<0.95 μm） 的过滤器中收集的空气颗粒显示富含碳的成分减少。使用拉曼光谱法分析每 1 cm² 开槽过滤器至少 20 个颗粒，这揭示了 MP 在不同槽中的均匀分布，并在级联采样器的第一阶段产生了 452 ± 134 MP/m³ 的浓度。检测到的 MP 在形态学上分为两大类：尺寸范围为 2.8-24.8 μm 的片段和尺寸范围为 28.6-212 μm 的纤维。 随后，这些颗粒被化学鉴定为炭黑（轮胎）和聚丙烯。总之，在尝试分析小至一微米的颗粒时，对尺寸分离的空气传播 MNP 进行基于颗粒的分析提出了一定的挑战，因为相关颗粒的空气动力学直径以及由此导致的相应分析限制变得特别成问题，尤其是对于小于 3 μm 的截止值。