Yang Zijiang, Arakawa Hisayuki
Department of Ocean Sciences, Tokyo University of Marine Science and Technology, Konan 4-5-7, Minato-Ku, Tokyo 108-8477, Japan.
MethodsX. 2023 Jun 15;11:102251. doi: 10.1016/j.mex.2023.102251. eCollection 2023 Dec.
Fourier-transform infrared (FT-IR) spectroscopy method for measuring small microplastic (SMP) concentration in marine environment is time-consuming and labor-intensive due to sample pre-treatment. In contrast, Raman spectroscopy is less influenced by water and can directly measure SMP samples in water, making it a more efficient method to measure SMP concentration. Therefore, a method that can directly estimate the concentration of SMPs in water was developed, and the relationship between SMP concentration and experimental Raman spectra were established by testing with standard polyethylene (PE) samples. It was found that average spectra acquired in water solution could reflect characteristic peaks of the plastic after baseline correction. Further investigation found that there is a significant functional relationship between correlation coefficient of sample spectra and the concentration of PE particles, and such relationship can be modelled by Langmuir model. The empirical functional relationships can be used to estimate SMP concentrations by measuring average Raman spectra. The developed methodology is helpful for developing rapid SMP identification and monitoring methods in a more complex manner.•A method of directly measuring MP concentration in water is proposed.•Experimental procedures are provided.•Data analysis methods are outlined.
傅里叶变换红外（FT-IR）光谱法用于测量海洋环境中的小微塑料（SMP）浓度时，由于样品预处理，该方法既耗时又费力。相比之下，拉曼光谱受水的影响较小，可以直接测量水中的SMP样品，使其成为测量SMP浓度更有效的方法。因此，开发了一种可以直接估算水中SMP浓度的方法，并通过使用标准聚乙烯（PE）样品进行测试，建立了SMP浓度与实验拉曼光谱之间的关系。研究发现，在水溶液中采集的平均光谱经基线校正后可以反映塑料的特征峰。进一步研究发现，样品光谱的相关系数与PE颗粒浓度之间存在显著的函数关系，并且这种关系可以用朗缪尔模型进行模拟。通过测量平均拉曼光谱，这些经验函数关系可用于估算SMP浓度。所开发的方法有助于以更复杂的方式开发快速的SMP识别和监测方法。
•提出了一种直接测量水中MP浓度的方法。
•提供了实验步骤。
•概述了数据分析方法。
