Rising plastic consumption leads to widespread microplastic (MP) contamination. Raman spectroscopy is widely used for MP identification due to its ability to analyse particles as small as 1 μm. However, it faces challenges such as interference from pigments and additives. In this study, we aim to assess the accuracy of Raman micro-spectroscopy in identifying coloured plastic samples by applying various oxidative treatments to eliminate the possible interference effect caused by colourants associated with the sample. Standard and coloured microplastics were analysed using a Raman imaging microscope. Coloured plastics were treated with H₂O₂ 30%, Sodium hypochlorite 5%, and Fenton reagent (H2O2 30% and Ferrous sulphate 0.2 M) for 24, 48, and 72 h. The Raman spectra were acquired after treatment to assess the impact of the treatment procedure on the polymer identification. Our results revealed that colourants significantly impact Raman spectra by peak broadening and/or fluorescence effects, which reduces identification accuracy and match scores Red pigments particularly obscure polymer identification. Treatments like oxidation and Fenton's reagent showed limited effectiveness. Additives in plastic samples can affect the accuracy of polymer identification by the Raman spectroscopy technique. Common treatment procedures do not improve the accuracy of identification. In order to improve the reliability of Raman analysis, essential factors such as utilizing multiple excitation lasers and appropriate CCD detectors, establishing a comprehensive reference library of colourants and additives, and employing advanced techniques like time-gated Raman spectroscopy or Surface-Enhanced Raman Spectroscopy (SERS) should be considered.

中文翻译：

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（微）塑料拉曼光谱的挑战：着色剂的干扰作用


塑料消费量的增加导致广泛的微塑料 （MP） 污染。拉曼光谱法因其能够分析小至 1 μm 的颗粒而广泛用于 MP 鉴定。然而，它面临着颜料和添加剂干扰等挑战。在本研究中，我们旨在通过应用各种氧化处理来评估拉曼显微光谱识别彩色塑料样品的准确性，以消除与样品相关的着色剂可能引起的干扰效应。使用拉曼成像显微镜分析标准和彩色微塑料。用 H₂O₂ 30%、次氯酸钠 5% 和 Fenton 试剂 （H 2 O 2 30% 和硫酸亚铁 0.2 M） 处理有色塑料 24 、 48 和 72 小时。处理后采集拉曼光谱，以评估处理程序对聚合物鉴定的影响。我们的结果表明，着色剂通过峰展宽和/或荧光效应显着影响拉曼光谱，这会降低识别准确性和匹配分数红色颜料尤其难以掩盖聚合物鉴定。氧化和 Fenton 试剂等处理效果有限。塑料样品中的添加剂会影响拉曼光谱技术对聚合物的鉴定准确性。常见的处理程序不会提高识别的准确性。为了提高拉曼分析的可靠性，应考虑一些基本因素，例如使用多个激发激光器和适当的 CCD 检测器，建立着色剂和添加剂的综合参考库，以及采用时间选通拉曼光谱或表面增强拉曼光谱 （SERS） 等先进技术。