Overcoming the fluorescent interference during Raman spectroscopy detection of microplastics

Yu Liu; Jiale Hu; Liqian Lin; Bing Yang; Minhua Huang; Min Chang; Xiaoxin Huang; Zhenqing Dai; Shengli Sun; Lei Ren; Chengyong Li

doi:10.1016/j.scitotenv.2023.165333

Overcoming the fluorescent interference during Raman spectroscopy detection of microplastics

Sci Total Environ. 2023 Nov 1:897:165333. doi: 10.1016/j.scitotenv.2023.165333. Epub 2023 Jul 5.

Authors

Yu Liu¹, Jiale Hu², Liqian Lin², Bing Yang², Minhua Huang², Min Chang², Xiaoxin Huang³, Zhenqing Dai⁴, Shengli Sun², Lei Ren⁵, Chengyong Li⁶

Affiliations

¹ School of Chemistry and Environment, Guangdong Ocean University, Zhanjiang 524088, China; Shenzhen Institute of Guangdong Ocean University, Shenzhen 518108, China.
² School of Chemistry and Environment, Guangdong Ocean University, Zhanjiang 524088, China.
³ Shenzhen Institute of Guangdong Ocean University, Shenzhen 518108, China.
⁴ Shenzhen Institute of Guangdong Ocean University, Shenzhen 518108, China; Guangdong Provincial Key Laboratory of Intelligent Equipment for South China Sea Marine Ranching, Guangdong Ocean University, Zhanjiang 524088, China. Electronic address: daizq@gdou.edu.cn.
⁵ Shenzhen Institute of Guangdong Ocean University, Shenzhen 518108, China; College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang 524088, China.
⁶ School of Chemistry and Environment, Guangdong Ocean University, Zhanjiang 524088, China; Shenzhen Institute of Guangdong Ocean University, Shenzhen 518108, China; Guangdong Provincial Key Laboratory of Intelligent Equipment for South China Sea Marine Ranching, Guangdong Ocean University, Zhanjiang 524088, China. Electronic address: cyli@gdou.edu.cn.

PMID: 37414187
DOI: 10.1016/j.scitotenv.2023.165333

Abstract

Owing to environmental concerns, microplastics pollution has been the object of increasing attention. Currently, the chemical composition of microplastics is commonly detected using Raman spectroscopy. Nevertheless, the Raman spectra of microplastics may be overlaid by signals derived from additives (e.g., pigment), resulting in serious interference. In this study, an efficient method is proposed to overcome the interference of fluorescence during Raman spectroscopic detection of microplastics. Four catalysts of Fenton's reagent (Fe²⁺, Fe³⁺, Fe₃O₄, and K₂Fe₄O₇) have been investigated for their capacity to generate hydroxyl radical (•OH), thus potentially eliminating the fluorescent signals in microplastics. The results indicate that the Raman spectrum of microplastics treated with Fenton's reagent can be efficiently optimized in the absence of spectral processing. This method has been successfully applied to the detection of microplastics collected from mangroves, featuring a range of colours and shapes. Consequentially, after 14 h of treatment with sunlight-Fenton (Fe²⁺: 1 × 10^-‍6 M, H₂O₂: 4 M), the Raman spectra matching-degree (RSMD) of all microplastics were >70.00 %. The innovative strategy discussed in this manuscript can greatly promote the application of Raman spectroscopy in the detection of real environmental microplastics, overcoming interfering signals derived from additives.

Keywords: Fenton's reagent; Fluorescence quenching; Matched-degree; Microplastics; Raman spectrometry.