This document establishes key principles for the investigation of microplastics in drinking water and water with low content of natural suspended solids using a microscopy technique coupled with vibrational spectroscopy.

This method is applicable to:

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determine the size of microplastics [which range from 1 µm to 5 000 µm], count them and classify them by size range;

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identify the chemical composition of microplastics, the main ones (most used in industry and most abundant in the environment) being: polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polycarbonate (PC), polystyrene (PS), polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), polyamide (PA), polymethyl methacrylate (PMMA) and polyurethane (PU);

This method is applicable to water with a low content of organic matter and other suspended matter as defined in ISO 6107 (1 mg/l to 100 mg/l or lower when interfering with the determination), i.e.,

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ultrapure water;

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water intended for human consumption;

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raw groundwaters.

Given the very low concentrations of microplastics usually present in these waters, special attention needs to be paid to potential sources of contamination during sample preparation.

This method is intended to determine and characterize large numbers of particles in the sample in automatic mode.

This method can also identify the nature of the other particles that are outside the scope of this document, for example minerals, proteins, cellulose and pigments.

This method does not apply to the characterization of substances intentionally added to or adsorbed on the surface of microplastics. This method does not apply to the determination of the geometric shape of microplastics.