环境和生物样品中小粒级微塑料的分离和鉴定方法

Marine microplastic pollution has become a global emerging contaminant. The methods of analysis have been well developed for > 50 μm microplastics from the field samples. However, great efforts are urgently needed to improve the minimum size limitation, the accuracy and the efficiency of separation and identification for < 50μ m microplastics from the field samples. In the present project, we propose that the 1-50 μm microplastics can be defined as "small-fraction microplastics". Firstly, we will choose the commercial plastic particles as the target materials for studying. The characteristics of small-fraction microplastics will be studied, and the methods of separation based on liquid floating and filtering will be built. The new method will be developed to use mica as the carrier for detecting samples. We will further develop the method of separation for the pure plastics as interior standards of microplastic added to the environmental samples. The surface structure and chemical composites of small-fraction microplastics will be analyzed using the microscopic and spectroscopic methods. The database of pure materials and additives of plastics will be built. Secondly, protease method will be used to digest the environmental and biological samples efficiently. Based on the work above, we will develop and optimize the new methods to separate small-fraction microplastics in the samples of water, sediment and biota based on plastic interior standards. We will further develop the new methods to identify microplastics based on the database of characteristics of plastics, additives and the impure materials in the samples. Finally, we will develop a comprehensive method to separate and identify the small-fraction microplastics efficiently and accurately. Our work will provide techniques and methods for the further study and monitoring of small-fraction microplastics.

海洋微塑料是一种全球性的新型污染物，目前对野外样品中尺寸在50 μm以上微塑料的分析方法相对成熟，但对更小粒级微塑料分离和鉴定的尺寸下限、精准度和效率还急待提高。本项目提出以1-50 μm的塑料作为“小粒级微塑料”的工作定义，首先以塑料纯品为对象，研究其在水相中的行为特征，以及不同重液和微孔滤膜分离微塑料的效果，探索运用云母基材作为待观测样品载片的新方法，筛选和制备用作环境样品内标的小粒级微塑料；通过显微观测和光谱分析等方法对塑料纯品进行微观结构表征和化学成分鉴定，建立纯品及其添加物的特征数据库；然后，探索蛋白酶在环境和生物样品深度消化中的运用，建立基于内标控制的小粒级微塑料分离，以及基于塑料、添加物和杂质特征数据库比对的定性甄别和定量表征的新方法；最后，建立运用多种观测手段对大批量野外样品中小粒级微塑料进行快速分离和准确鉴定的综合方法。项目将为今后研究和监测小粒级微塑料提供技术方法。

鉴于目前对野外样品中尺寸在50μm以上微塑料的分析方法相对成熟，但对更小粒级微塑料分离和鉴定方法有待进一步探索这一现实，我们对小于50μm的微塑料开展了深入研究。首先，我们进行了小粒级微塑料纯品的制备、物理特性表征和化学谱库的建立，发展了微塑料纯品的计数、梯度密度测定法和难区分化学组分的鉴别方法等；其次，建立了基于膜过滤和低速离心的小粒级微塑料的快速分级分离方法并开发了相应的分离装置，以及利用超高速离心对水样中纳米塑料分离的方法；再次，建立了基于显微拉曼和表面增强拉曼的小粒级微塑料鉴定方法，对从高度老化塑料上分离的小颗粒样品的化学分析下限达到620nm，并开发了基于光刻硅基底的小粒级微塑料的综合表征技术，实现了小粒级微塑料图与谱的有效结合；最后，我们成功将小粒级微塑料分析方法运用于多项实际环境样品的调查研究中，并系统总结和分析了环境微纳塑料的前处理、分离、鉴定和定量的方法。对环境样品中20μm以下小粒级微塑料的分离效率还有待提高。本项目的实施为今后研究和监测小粒级微塑料提供了方法学手段和技术支撑。