Ren Pengju, Luo Shusheng, Wang Lijuan, Chi Yihan, Tang Yuanyuan
Guangdong Provincial Key Laboratory of Soil and Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology Shenzhen 518055 P. R. China
RSC Adv. 2025 Aug 19;15(36):29217-29229. doi: 10.1039/d5ra00409h. eCollection 2025 Aug 18.
Nanoplastics (NPs) are an emerging contaminant in natural freshwater environments. However, there is a lack of analytical methods for separating and characterizing NPs by particle size, which is essential for analyzing their environmental behavior. Asymmetrical flow field-flow fractionation (AF4) is considered a reliable technique suitable for separating and characterizing the particle size of macromolecules, colloids, and particles. In this work, we report a method for separating and characterizing the size of polystyrene nanoplastics (PS NPs) in freshwater environments using AF4 coupled with MALS and UV-vis detectors. By optimizing the injection volume, mobile phase composition, cross-flow rate, and detector flow rate, we achieved the separation of 50 nm and 100 nm PS NPs within 40 min. The average mass recovery rate reached 88.5%, with relative standard deviations of less than 10% for different indicators in repeated measurements. The value of the linear regression between concentration and UV peak area exceeded 0.99. We applied this method to natural freshwater media and analyzed the particle sizes of particles added to the freshwater media for 0 and 48 hours using dynamic light scattering (DLS). The results revealed that, despite the appearance of a small number of particle aggregates with sizes close to 250 nm in some freshwater media after 48 hours, the optimized AF4 method still effectively separated the majority of the original unaggregated particles. This effective separation demonstrates the practical feasibility of applying the AF4 method to environmental water samples.
纳米塑料（NPs）是天然淡水环境中一种新出现的污染物。然而，目前缺乏按粒径分离和表征纳米塑料的分析方法，而这对于分析其环境行为至关重要。非对称流场-流分馏（AF4）被认为是一种适用于分离和表征大分子、胶体及颗粒粒径的可靠技术。在本研究中，我们报道了一种使用AF4结合多角度激光光散射（MALS）和紫外可见（UV-vis）检测器来分离和表征淡水环境中聚苯乙烯纳米塑料（PS NPs）粒径的方法。通过优化进样体积、流动相组成、错流速率和检测器流速，我们在40分钟内实现了50纳米和100纳米PS NPs的分离。平均质量回收率达到88.5%，重复测量中不同指标的相对标准偏差小于10%。浓度与紫外峰面积之间的线性回归值超过0.99。我们将该方法应用于天然淡水介质，并使用动态光散射（DLS）分析了添加到淡水介质中0小时和48小时后的颗粒粒径。结果表明，尽管48小时后在一些淡水介质中出现了少量尺寸接近250纳米的颗粒聚集体，但优化后的AF4方法仍能有效分离出大多数原始未聚集的颗粒。这种有效分离证明了将AF4方法应用于环境水样的实际可行性。
