环境中金属纳米材料分离及测定方法研究进展

Research advances in separation and determination of metallic nanomaterials in the environment

金属纳米材料因其大量生产和广泛使用而不可避免地会释放到环境中,给生态环境和人体健康造成潜在的负面影响.发展环境样品中金属纳米材料高效灵敏的分析测定方法,对于研究其在环境中的分布、转化、归趋、效应和生物安全性具有重要意义.研究表明,金属纳米材料组成、结构、形态和粒径分布等显著影响其环境过程和生物效应.因此,与传统的污染物分析不同,金属纳米材料分析不仅需要测定其化学组成和浓度,还需表征其粒径、形貌和表面电荷等.本文综述了近十年来关于环境中金属纳米材料的分离及测定的相关手段和方法,主要包括痕量金属纳米颗粒的萃取富集方法以及不同粒径纳米颗粒和相应金属离子的分离方法,并展望了发展前景.

With the mass production and wide application of metallic nanoparticles （MNPs）, there is a likelihood of their re- lease into the environment, and therefore considerably increased potential adverse effects on both ecosystem and human health. To understand their occurrence, distribution, transport, fate, effects and biosafety, it is of great im- portance to develop methods for efficient and sensitive determination of MNPs in the environment. Unlike tradi- tional pollutants, the composition, structure, species and size of MNPs have remarkable impacts on their environ- mental processes and biological effects, thus it is necessary to determine their composition and concentration, as well as to characterize their size, shape and surface charge. Here, we review the updated methods for analysis of MNPs in the environment in the past ten years, which can be cataloged into the extraction and preconcentration methods, or the separation and determination methods. Ex- traction and preconcentration methods, including cloud point extraction （CPE）, liquid liquid extraction （LLE） and solid phase extraction （SPE）, can selectively separate the MNPs from the matrices and therefore enhance the detec- tion limit. However, these methods are unable to separate different sized MNPs, and further characterization tech- niques are needed to obtain the detailed information on the MNP size and shape. Combination of the size fractiona- tion techniques, such as chromatographic methods, electrophoresis and field flow fractionation （FFF）, with highly sensitive detectors like inductively coupled plasma mass spectrometry （ICP-MS） are highly promising i.l assessment of size and shape-related information of the MNPs and their aggregates. Unfortunately, the hyphenated techniques are difficult to satisfy the requirement of MNP determination at the environmental levels. Single particle ICP-MS （splCP-MS） is an elegant method for simultaneous determination of the size distribution and concentration of MNPs in the environment, but it still remians a great challenge to determine the small sized MNPs （〈20 nm）, as the small sized MNPs are hardly discriminated with the corresponding metal ions. Therefore, these methods have their own advantages and disadvantages and can complement each other. Currently, great achievements have been gained in the analysis of MNPs. To accurately appraise the exposure risks for environmental and human health arising from MNP production, application and disposal, however, some issues are still needed to be solved, mainly including the following four aspects： （1） relatively complete and scientific standard methods for analysis of MNPs in the environment, covering sampling, pretreatment, quantification and characterization, still require further development; （2） methods for extraction of MNPs from soil and sediment, which can maintain the original size and shape of MNPs, are urgently needed; （3） the detection limits of the existing techniques are still too high to satisfy the determination of MNPs at the environmental levels, therefore, methods with a high sensitivity are desiderated; （4） the co-existance of natural MNPs greatly complicates the risk assessment of the engineered MNPs in the environment, therefore, it is of vital importance to develop techniques to distinguish between natural and engineered MNPs.