典型无机盐对紫外-可见吸收光谱法测定聚苯乙烯纳米塑料的影响与修正方法 ^*

UV-Vis absorption spectroscopic measurements of polystyrene nanoplastics - interference from NaCl, MgCl ₂, CaCl ₂ and their corrections

摘要

微/纳米塑料（micro/nano-plastics，M/NPs）广泛分布于环境水体且作为污染物载体对水生生物产生危害. 紫外-可见吸收光谱法（UV-Vis）操作便捷、灵敏度高，在环境分析中具有应用潜力. 本文以聚苯乙烯纳米塑料（PSNPs， φ=100 nm）为研究对象，通过采用 UV-Vis 全波段（190~1 100 nm）扫描测定吸收光谱图，分析了 NaCl、MgCl₂、CaCl₂ 这 3 种无机盐对 UV-Vis 检测 PSNPs 的光谱干扰规律，并基于光强度构建红移修正非线性模型. 结果表明，PSNPs 与 NaCl、MgCl₂、CaCl₂ 在 190~340 nm 波段存在吸收重叠，Cl^-浓度增加诱导谱带红移，使浓度与吸光度的线性关系偏离 Lambert-Beer 定律，干扰 PSNPs 定量分析. 以红移量修正并构建非线性定量模型，3 种盐溶液的拟合优度（ R²_adj）提升至 0.998~0.999. 基于混合体系对模型验证，表明 NaCl 溶液中 PSNPs 预测吸光度达相应标准值的（98.2±3.0）%，但因 MgCl₂、CaCl₂ 浓度接近或超过其临界团聚浓度（CCC），诱导 PSNPs 聚沉而吸光度明显下降. 构建的非线性修正模型可有效提高定量分析的准确性，为环境水体中 M/NPs 的光谱定量分析提供方法支持.

Abstract

Micro/nanoplastics (M/NPs) are widely distributed in aquatic environments, are significant threats to aquatic life as carriers of pollutants. Ultraviolet-visible (UV-Vis) spectrophotometry, due to simplicity and sensitivity, holds potential for environmental analysis. The UV-Vis absorption spectra (190-1 100 nm) of polystyrene nanoplastics (PSNP, φ = 100 nm) were measured. Spectral interference from NaCl, MgCl ₂ and CaCl ₂ were analyzed. PSNP and these inorganic salts showed overlap in absorption in the region of 190-340 nm. Increases in Cl ^- concentration were found to induce redshifts in resultant spectra, leading to deviations from the Lambert-Beer law, to interfer with the quantitative determination of PSNPs. Redshifts were corrected to construct a nonlinear quantitative model, with goodness-of-fit ( R ² _adj) for NaCl, MgCl ₂, and CaCl ₂ solutions improved to 0.998-0.999. Model validation using mixed systems indicated that predicted absorbance of PSNPs in NaCl solution reached (98.2 ± 3.0)% of standard values. However, when MgCl ₂ and CaCl ₂ concentrations approached or exceeded critical coagulation concentration (CCC), aggregation and sedimentation of PSNPs occurred, resulting in a significant decrease in absorbance. Overall, the proposed redshift-corrected nonlinear model could effectively enhance accuracy of quantitative M/NPs analysis of environmental waters.

关键词

微/纳米塑料 / 紫外-可见吸收光谱法 / 谱带红移 / 无机盐 / 定量分析模型

Key words

micro/nanoplastics / UV-Vis / spectral redshift / inorganic salts / quantitative analysis model

参考文献

[1] 曾永平 . 环境微塑料概论[M]. 北京: 科学出版社, 2020

[2] Yan M T, Nie H Y, Xu K H, et al. Microplastic abundance, distribution and composition in the Pearl River along Guangzhou city and Pearl River estuary, China[J]. Chemosphere, 2019, 217: 879

[3] 刘炜婷 . 基于 RS-CPE-μ-FTIR 的珠江广州河段微塑料污染风险评估研究[D]. 广州: 广东药科大学, 2021

[4] 张龙飞, 刘玉环, 阮榕生, 等 . 微塑料的形成机制及其环境分布特征研究进展[J]. 环境科学, 2023, 44(8): 4728

[5] Li W, Zou H W, Zheng Y G, et al. Microplastics in aquatic environments: detection, abundance, characteristics, and toxicological studies[J]. Environmental Monitoring and Assessment, 2025, 197(2): 150

[6] Kosuth M, Mason S A, Wattenberg E V . Anthropogenic contamination of tap water, beer, and sea salt[J]. PLoS One, 2018, 13(4): e0194970

[7] Onyedibe V, Kakar F L, Okoye F, et al. Sources and occurrence of microplastics and nanoplastics in the environment[M]// Current Developments in Biotechnology and Bioengineering. Amsterdam: Elsevier, 2023: 33

[8] 姚情璐, 杨超, 翟宇辉, 等 . 环境水体中微塑料分析方法研究进展[J]. 净水技术, 2022, 41(10): 23

[9] 糜自栋, 孙韶华, 宋武昌, 等 . 水环境中微塑料污染物研究进展[J]. 工业水处理, 2022, 42(8): 1

[10] Jung S, Cho S H, Kim K H, et al. Progress in quantitative analysis of microplastics in the environment: a review[J]. Chemical Engineering Journal, 2021, 422: 130154

[11] 汪志国, 齐文启 . 紫外可见分光光度法及其在环境监测中的应用[J]. 现代科学仪器, 1998(6): 36

[12] Ifon B E, Rashid A, Suanon F, et al. Comprehensive optical analysis of aqueous dissolved organic matter: from sampling techniques to analytical interpretation[J]. Microchemical Journal, 2025, 212: 113437

[13] Birkmann J, Pasel C, Luckas M, et al. UV spectroscopic properties of principal inorganic ionic species in natural waters[J]. Water Practice and Technology, 2018, 13(4): 879

[14] Guan L, Tong Y F, Li J W, et al. Research on ultraviolet-visible absorption spectrum preprocessing for water quality contamination detection[J]. Optik, 2018, 164: 277

[15] Zhu Y Z, Song Y H, Yu H B, et al. Characterization of dissolved organic matter in Dongjianghu Lake by UV-visible absorption spectroscopy with multivariate analysis[J]. Environmental Monitoring and Assessment, 2017, 189(9): 443

[16] Mäntele W, Deniz E . UV-VIS absorption spectroscopy: Lambert-Beer reloaded[J]. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2017, 173: 965

[17] Yang X H, An C J, Feng Q, et al. Aggregation of microplastics and clay particles in the nearshore environment: characteristics, influencing factors, and implications[J]. Water Research, 2022, 224: 119077

[18] Wu J Y, Liu J Y, Wu P X, et al. The heteroaggregation and deposition behavior of nanoplastics on Al₂O₃ in aquatic environments [J]. Journal of Hazardous Materials, 2022, 435: 128964

[19] Yeh Y C, Ebbing T, Frick K, et al. Improving determination of pigment contents in microalgae suspension with absorption spectroscopy: light scattering effect and Bouguer-Lambert-Beer law[J]. Marine Drugs, 2023, 21(12): 619

[20] Currie L A . Detection and quantification limits: origins and historical overview[J]. Analytica Chimica Acta, 1999, 391(2): 127

[21] Marcus Y. Effect of ions on the structure of water: structure making and breaking[J]. Chemical Reviews, 2009, 109(3): 1346

[22] Tong A X, Tang X J, Zhang F, et al. Predicting the redshift on the ultraviolet spectrum using the peak area method[J]. Applied Optics, 2020, 59(7): 1823

[23] Johnson K S, Coletti L J . In situ ultraviolet spectrophotometry for high resolution and long-term monitoring of nitrate, bromide and bisulfide in the ocean [J]. Deep Sea Research Part Ⅰ: Oceanographic Research Papers, 2002, 49(7): 1291

[24] Collos Y, Mornet F, Sciandra A, et al. An optical method for the rapid measurement of micromolar concentrations of nitrate in marine phytoplankton cultures[J]. Journal of Applied Phycology, 1999, 11(2): 179

[25] Tong A X, Tang X J, Zhang F, et al. Study on the shift of ultraviolet spectra in aqueous solution with variations of the solution concentration[J]. Spectrochimica Acta Part A, Molecular and Biomolecular Spectroscopy, 2020, 234: 118259

[26] Ikehata A, Morisawa Y . Observation of solid-liquid phase transitions of brine using the far-ultraviolet charge-transfer-to-solvent band[J]. The Journal of Physical Chemistry B, 2023, 127(28): 6325

[27] Winter B, Aziz E F, Ottosson N, et al. Electron dynamics in charge-transfer-to-solvent states of aqueous chloride revealed by Cl^- 2p resonant auger-electron spectroscopy [J]. Journal of the American Chemical Society, 2008, 130(22): 7130

[28] Zhao Z, Rogers D M, Beck T L . Polarization and charge transfer in the hydration of chloride ions[J]. The Journal of Chemical Physics, 2010, 132: 014502

[29] Shams M, Alam I, Chowdhury I . Aggregation and stability of nanoscale plastics in aquatic environment[J]. Water Research, 2020, 171: 115401

基金资助

国家自然科学基金资助项目(42207465)

广州市基础研究计划资助项目(SL2023A04J01566)