Microplastic analysis in drinking water based on fractionated filtration sampling and Raman microspectroscopy

Area of Science:

• Environmental Science
• Analytical Chemistry
• Polymer Science

Background:

• Microplastics (MPs) are persistent pollutants found globally in water sources.
• Existing analytical methods for MP detection lack harmonization, necessitating standardized protocols.
• Understanding MP contamination in drinking water is crucial for public health.

Purpose of the Study:

• To develop and validate a comprehensive analytical workflow for microplastic analysis in aqueous matrices.
• To establish standardized protocols for sampling, sample preparation, and analysis of MPs down to 5 micrometers.
• To quantify and characterize microplastic contamination in drinking water and groundwater samples.

Main Methods:

• Development of a portable filter cascade unit for sampling large water volumes (cubic meters) with pore sizes of 100, 20, and 5 µm.
• Semi-automated Raman microspectroscopy for determining MP size distribution and polymer types.
• Implementation of comprehensive process blanks and recovery tests for quality control.

Main Results:

• The validated workflow successfully analyzed microplastics down to 5 µm in drinking water, tap water, and groundwater.
• Average MP concentration was 66 ± 76 MP/m³, well below the limit of quantitation.
• Polyethylene (PE) was the predominant polymer (86%), followed by PET (10%), PP (3%), and PA (1%). 79% of particles were smaller than 20 µm.

Conclusions:

• The presented holistic workflow provides a standardized approach for microplastic analysis in aqueous environments.
• The study indicates no significant microplastic contamination in the tested drinking water and groundwater samples.
• The findings highlight the prevalence of smaller microplastic particles and polyethylene as a dominant polymer type.