基于预热解-自动化固相微萃取技术分析水中微塑料的方法研究

Determination of Microplastics in Water by Pre-pyrolysis Coupled with Automated Solid-phase Microextraction

  • 摘要: 灵敏高效分析环境介质中的微塑料(MPs)可为其监测与防治提供重要的技术支撑。本文针对当前微塑料检测过程中存在的样品前处理步骤繁琐、自动批量化处理不足等问题,基于Gerstel多功能样品前处理平台,开发了一种预热解结合自动化固相微萃取(SPME)气相色谱-质谱法(GC-MS)分析水体中聚丙烯(PP)、聚苯乙烯(PS)、聚偏二氯乙烯(PVDC)、聚偏二氟乙烯(PVDF)、聚乙烯(PE)和聚对苯二甲酸乙二醇酯(PET)共6种微塑料的方法。研究表明在自制预热解装置中,微塑料于450℃下加热20 min即可完成热解。采用PDMS/DVB/CAR商用涂层对热解产物进行固相微萃取,并结合GC-MS成功鉴定出6种微塑料的热解产物,进而依据其热解化合物的结构差异,遴选出各自的特征标志物。实验优化了热解温度、热解时间、萃取温度、萃取时间等因素对萃取效率的影响。在最佳条件下,该方法线性范围优异,其中PP、PS、PVDC和PVDF的线性范围为1~10000 ng/L,PE和PET的线性范围为10~10000 ng/L;方法检出限为0.046~3.5 ng/L,定量限为0.16~12.1 ng/L;相对标准偏差(RSD)≤12.9%;应用于实际水样中微塑料的测定,加标回收率为75.2%~116.4%。该方法集成了批量化热解与自动化SPME技术,实现了微塑料热解产物的一体化萃取与浓缩,不仅简化了前处理流程,还显著提高了检测灵敏度与通量,为环境介质中微塑料的高效、灵敏检测提供了新途径。

     

    Abstract: Sensitive and efficient analysis of microplastics (MPs) in environmental media provides essential support for monitoring MPs and informing preventive measures. To address the current challenges in MPs detection, such as complex sample pretreatment steps and insufficient automated batch processing, a method that integrates pre-pyrolysis with automated solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) for extracting and analyzing six microplastics including polypropylene (PP), polystyrene (PS), polyvinylidene chloride (PVDC), polyvinylidene fluoride (PVDF), polyethylene (PE), and polyethylene terephthalate (PET) in aquatic samples was proposed based on the Gerstel Multi-Purpose Sampler platform. Results demonstrate that MPs undergo efficient pyrolysis after 20 minutes at 450℃ in a self-constructed preheating pyrolysis apparatus. SPME of the pyrolysis products was performed using a commercial PDMS/DVB/CAR-coated fiber, and the pyrolysis products of six MPs were identified by GC-MS. Subsequently, polymer-specific marker compounds were selected for each MPs based on differences in the structures of their pyrolysis products. The effects of pyrolysis temperature, pyrolysis time, extraction temperature, and extraction time on extraction efficiency were optimized. Under optimal conditions, the method exhibited excellent linear ranges, with PP, PS, PVDC, and PVDF having a range of 1–10000 ng/L, and PE and PET having a range of 10–10000 ng/L. The detection limits and quantification limits of the method were 0.046–3.5 ng/L and 0.16–12.1 ng/L, respectively, with relative standard deviations ≤12.9%. The method was applied to the determination of MPs in real water samples, with recoveries ranging from 75.2% to 116.4%. In this study, batch pyrolysis was integrated with automated SPME technique to achieve the integrated extraction and concentration of pyrolysis products from MPs. The approach streamlined pretreatment and substantially improved detection sensitivity and throughput, offering a novel, efficient method for detecting MPs in environmental matrices.

     

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