Standardized Method for the Identification and Quantification of Microplastics in Wastewater Using LDIR Microscopy

Building Consensus Methods to Support Environmental Laboratories
Oral Presentation

Prepared by J. Prevatt
Pima County Regional Wastewater Reclamation, 2955 W Calle Agua Nueva, Tucson, AZ, 85745, United States


Contact Information: jeff.prevatt@pima.gov; 520-724-6060

ABSTRACT

The presence of microplastics in the aquatic environment has become an increasing global concern. Toxicity resulting from ingestion, bioaccumulation and organic pollutants adsorbed on microplastic particles is presently unknown. A large impediment to our understanding the associated health risks is a lack of standardized analytical methods readily available for the quantitative characterization of microplastic polymers in the environment. Wastewater discharges are known to contain microplastic polymers in varying quantities and the presence of large quantities of organic matter further complicates identification and quantification.
Over the last three years, our team has worked under contract to EPA to develop a standardized ASTM method for the analysis of microplastic particles in high turbidity wastewaters. Our research has focused on both IR and Raman microscopy with the use of focal plane array spectroscopy to bridge the analytical gap. After extensive literature review and evaluation of numerous sample preparation techniques, we have been able to produce ASTM guidances for the collection, preparation and analysis of microplastics in wastewater matrices.
This presentation will not only describe the current methodology currently under ASTM committee review but will also highlight the use of a novel laser direct IT chemical imaging system for the analysis of microplastic in the environment. Not only is it able to positively identify microplastic polymers by composition type and size distribution, it allows for unprecedented analysis speed previously unavailable to analysts.