The analysis of microplastics in complex environmental samples requires the use of chemicals to reduce the organic matrix. This procedure should be evaluated in terms of the preservation of the microplastic's integrity, typically done with pristine reference microplastics. However, real microplastics are most likely degraded due to weathering, so pristine reference microplastics might not depict the appropriateness of the process. This study performed a purification process using sodium dodecyl sulfate and hydrogen peroxide on sewage sludge containing LLDPE, HDPE, PP, PS, PET, PA66 and SBR samples exposed to simulated environmental weathering. The degradation of the polymers was assessed by analyzing surface morphology, mass variation, and mechanical, thermal and chemical properties. Comparison with pristine polymers revealed that the purification process can lead to more detrimental effects if the polymers are weathered. After the purification process, some important observations were: 1) LLDPE, PP and SBR surfaces had cracks in the weathered samples that were not observed in the pristine samples, 2) weathered LLDPE, PP and PA66 experienced greater mass loss than pristine, 3) the fragmentation propensity of weathered LLDPE, HDPE, PP, PS and SBR increased compared to pristine samples and 4) the main characteristic peaks in FTIR spectrum could be identified and used for chemical identification of most polymers for pristine and weathered samples. Based on the findings of this study, when analyzing the efficiency and adequacy of a purification process with methods based on surface morphology, mass variation and particle counting indicators, it is recommended to consider the differences that potentially arise between pristine and weathered microplastics, especially for polyolefins (PEs and PP).

复杂环境样品中的微塑料分析需要使用化学品来减少有机基质。该程序应根据微塑料完整性的保存情况进行评估，通常使用原始参考微塑料进行。然而，真正的微塑料很可能由于风化而降解，因此原始参考微塑料可能无法描述该过程的适当性。本研究使用十二烷基硫酸钠和过氧化氢对暴露于模拟环境风化的含有 LLDPE、HDPE、PP、PS、PET、PA66 和 SBR 样品的污水污泥进行了净化过程。通过分析表面形态、质量变化以及机械、热和化学性质来评估聚合物的降解。与原始聚合物的比较表明，如果聚合物被风化，纯化过程会导致更有害的影响。在净化过程之后，一些重要的观察结果是：1) LLDPE、PP 和 SBR 表面在风化样品中存在裂纹，而在原始样品中没有观察到，2) 风化 LLDPE、PP 和 PA66 比原始样品经历更大的质量损失，3)与原始样品相比，风化 LLDPE、HDPE、PP、PS 和 SBR 的碎裂倾向增加，并且 4) 可以识别 FTIR 光谱中的主要特征峰，并将其用于原始和风化样品的大多数聚合物的化学鉴定。根据本研究的结果，在使用基于表面形态的方法分析纯化过程的效率和充分性时，