Optimizing Membrane Filter Selection for Analytical Methods Used to Characterize Microplastics in the EnvironmentAnalyzing Microplastics in the Environment
Oral Presentation
Prepared by L. Lozeau1, R. Muralidharan2, M. Dube1
1 - MilliporeSigma, 600 Summit Drive, Burlington, MA, 01803, United States
2 - MilliporeSigma, 3050 Spruce Street, St. Louis, MO, 63178, United States
Contact Information: [email protected]; 781-496-5656
ABSTRACT
The ubiquitous presence of microplastics (plastic particles, 1-5 μm in size from many different sources), combined with the growing evidence of their adverse effects on human health and aquaculture has propelled these emerging contaminants to the forefront of global regulatory attention. Due to their heterogenicity in size, shape, material, color, and degradation state, it is difficult to analyze them using a single technique. Thus, many techniques have been proposed for detecting microplastics in environmental matrices, such as microscopic, spectroscopic, and chromatographic methods. Most of these protocols involve filtration-based sample preparation and microplastic isolation. Notably, each analytical technique has unique filter requirements, and it remains unclear how to optimally select the right filter for the desired technique. Development of regulatory methods for characterizing microplastics is still in early stages; however, based on the technical complexity, it is expected that methods will accommodate multiple analytical techniques. Thus, to better understand the role of membrane filters in these diverse analytical workflows, several studies of different membrane filter types (such as polycarbonate and glass fiber) were performed.
- Filter particle retention studies to determine filters suitable to create microplastics analysis grade (MAG) water.
- Chemical and temperature compatibility testing to investigate suitability of filters for the common digestion methods.
- Evaluation of filter throughput for isolating microplastics separated using oil.
- Studies on filter handleability, microplastic particle recovery, and background signals for microscopy-based analytical methods—light microscopy, fluorescent microscopy using Nile Red, and electron microscopy.
Additionally, filter properties and suitability for Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and gas chromatography with pyrolysis sample preparation were collated in order to determine suitable filters by method. These studies provide valuable insights on choosing the optimal membrane filter for the accurate isolation, identification, analysis and characterization of microplastics in environmental matrices.
