Background

The ubiquitous occurrence of microplastic particles in marine and aquatic ecosystems was intensively investigated in the past decade. However, we know less about the presence, fate, and input paths of microplastic in terrestrial ecosystems. A possible entry path for microplastic into terrestrial ecosystems is the agricultural application of sewage sludge and solid bio-waste as fertilizers. Microplastic contained in sewage sludge also includes polyethylene terephthalate (PET), which could originate as fiber from textile products or as a fragment from packaging products (foils, bottles, etc.). Information about microplastic content in such environmental samples is limited yet, as most of the used analytical methods are very time-consuming, regarding sample preparation and detection, require sophisticated analytical tools and eventually need high user knowledge.

Results

Here, we present a simple, specific tool for the analysis of PET microplastic particles based on alkaline extraction of PET from the environmental matrix and subsequent determination of the monomers, terephthalic acid, using liquid chromatography with UV detection (LC-UV). The applicability of the method is shown for different types of PET in several soil-related, terrestrial environmental samples, e.g., soil, sediment, compost, fermentation residues, but also sewage sludge, suspended particles from urban water management systems, and indoor dust. Recoveries for model samples are between 94.5 and 107.1%. Limit of determination and limit of quantification are absolute masses of 0.031 and 0.121 mg PET, respectively. In order to verify the measured mass contents of the environmental samples, a method comparison with thermal extraction-desorption-gas chromatography–mass spectrometry (TED-GC/MS) was conducted. Both methods deliver similar results and corroborated each other. PET mass contents in environmental samples range from values below LOQ in agriculture soil up to 57,000 mg kg⁻¹ in dust samples.

Conclusions

We demonstrate the potential of an integral method based on chemical extraction for the determination of PET mass contents in solid environmental samples. The method was successfully applied to various matrices and may serve as an analytical tool for further investigations of PET-based microplastic in terrestrial ecosystems.

中文翻译：

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使用化学萃取和LC-UV分析进行微塑性分析：测定环境样品中PET含量的直接方法

背景

在过去十年中，对海洋和水生生态系统中普遍存在的微塑性颗粒进行了深入研究。但是，我们对陆地生态系统中微塑料的存在，命运和输入途径知之甚少。微塑料进入陆地生态系统的可能进入途径是农业污泥和固体生物废物作为肥料的应用。污水污泥中包含的微塑料还包括聚对苯二甲酸乙二酯（PET），聚对苯二甲酸乙二酯可能来自纺织产品的纤维，也可能来自包装产品（箔，瓶等）的碎片。由于此类样品的大多数分析方法都非常耗时，因此有关此类样品中的微量塑料含量的信息非常有限，

结果

在这里，我们介绍了一种简单，特定的工具，用于基于从环境基质中碱提取PET并随后使用液相色谱和紫外检测（LC-UV）测定单体对苯二甲酸的方法来分析PET微粒。该方法适用于几种与土壤有关的陆地环境样品中不同类型的PET，例如土壤，沉积物，堆肥，发酵残留物，还有污水污泥，城市水管理系统中的悬浮颗粒和室内灰尘。模型样品的回收率在94.5至107.1％之间。测定极限和定量极限分别是0.031和0.121 mg PET的绝对质量。为了验证环境样品中测得的质量含量，进行了热萃取-解吸-气相色谱-质谱（TED-GC / MS）的方法比较。两种方法均提供相似的结果并相互证实。环境样品中的PET质量含量范围从农业土壤中低于最低限度的值到57,000 mg kg灰尘样品中的^-1。

结论

我们展示了一种基于化学提取的整体方法测定固体环境样品中PET质量含量的潜力。该方法已成功应用于各种基质，可作为进一步研究陆地生态系统中基于PET的微塑料的分析工具。