We tested the suitability of asymmetric flow field-flow fractionation (AF4) coupled to multi-angle light scattering (MALS) for detection of nanoplastics in fish. A homogenized fish sample was spiked with 100 nm polystyrene nanoparticles (PSNPs) (1.3 mg/g fish). Two sample preparation strategies were tested: acid digestion and enzymatic digestion with proteinase K. Both procedures were found suitable for degradation of the organic matrix. However, acid digestion resulted in large PSNPs aggregates/agglomerates (> 1 μm). The presence of large particulates was not observed after enzymatic digestion, and consequently it was chosen as a sample preparation method. The results demonstrated that it was possible to use AF4 for separating the PSNPs from the digested fish and to determine their size by MALS. The PSNPs could be easily detected by following their light scattering (LS) signal with a limit of detection of 52 μg/g fish. The AF4-MALS method could also be exploited for another type of nanoplastics in solution, namely polyethylene (PE). However, it was not possible to detect the PE particles in fish, due to the presence of an elevated LS background. Our results demonstrate that an analytical method developed for a certain type of nanoplastics may not be directly applicable to other types of nanoplastics and may require further adjustment. This work describes for the first time the detection of nanoplastics in a food matrix by AF4-MALS. Despite the current limitations, this is a promising methodology for detecting nanoplastics in food and in experimental studies (e.g., toxicity tests, uptake studies).

中文翻译：

---

通过不对称流场-流分离与多角度光散射耦合检测食品中的纳米塑料：可能性，挑战和分析局限性

我们测试了不对称流场流分馏（AF4）与多角度光散射（MALS）耦合在鱼类中检测纳米塑料的适用性。将均质的鱼样品掺入100 nm聚苯乙烯纳米颗粒（PSNP）（1.3 mg / g鱼）。测试了两种样品制备策略：酸消化和蛋白酶K的酶消化。发现两种方法都适合降解有机基质。但是，酸消化会导致较大的PSNP聚集体/团聚体（> 1μm）。酶消化后未观察到大颗粒的存在，因此将其选择为样品制备方法。结果表明，可以使用AF4从消化的鱼中分离PSNP，并通过MALS确定其大小。通过追踪其光散射（LS）信号，检出限为52μg/ g鱼，可以轻松检测PSNP。AF4-MALS方法也可用于溶液中另一种类型的纳米塑料，即聚乙烯（PE）。但是，由于存在较高的LS背景，因此无法检测鱼类中的PE颗粒。我们的结果表明，针对某种类型的纳米塑料开发的分析方法可能无法直接应用于其他类型的纳米塑料，并且可能需要进一步调整。这项工作首次描述了通过AF4-MALS检测食品基质中的纳米塑料。尽管存在当前的局限性，但这还是一种用于检测食品和实验研究（例如毒性试验，吸收研究）中的纳米塑料的有前途的方法。