Standards Development

Scope

This document specifies a preparation method for the extraction of microplastics from water matrices such as terrestrial waters, wastewater, seawater, and groundwater. The method outlines the most reliable preparatory procedures that assure polymer stability and high recovery rates, precautions to prevent contamination, and quality control procedures.

This document does not describe sampling methods and subsequent analytical methods. ISO 5667-27 should be referred to water sampling. ISO/DIS 16094-2 and ISO/DIS 16094-3 should be used for analysis for the identification and quantification of extracted microplastics depending on the purpose of monitoring.

Purpose

Microplastics (MPs) which are defined as pieces with the largest dimension between 1m and 5 mm are recognised globally as a highly diverse and multifaceted environmental contaminant.

The number of reports on the measurement of MPs has increased exponentially over the last two decades. However, reliable analytical methods for analysis have not been established due to the complexity of the sample matrices. The establishment of analysis methods has been necessary since global surveys on the sources, state of distribution, fate and ecological and human health impacts of MPs began.

The analysis of MPs is divided into three stages: sampling, sample preparation, and measurement (instrumental analysis). Sample preparation procedure affects the result of MPs measurements. However, each laboratory has its tailor-made method for preparatory procedures performed prior to instrumental analysis. This leads to be differences in the result of MPs analysis between laboratories. Standardization of the sample preparation method is necessary to obtain comparable data. This document provides the most reliable preparatory procedures for water samples from containing large to small amounts of foreign materials before subsequent analysis. Specified preparation procedures in the document referred to international and national guidelines [1][2][3][4], the EUROqCHARM critical review [5], and the result of an interview survey of eleven laboratories in eight countries which were conducted in TC147/SC2/JWG1. Manual preparation procedures are described in the main text. An automated preparation apparatus, which can perform the digestion and density separation automatically is described in Annex A.

This document addresses sample preparation for MPs detection by µFTIR, µRaman, Py-GC-M or TEDGC-MS. It does, though, not describe the sampling method and instrumental analysis for MPs. For this refer to ISO5667-27 for sampling and ISO/FDIS 16094-2 and ISO/DIS 16094-3 for analysis.

[1]Michida, Y., et al. (2023) Guidelines for Harmonizing Ocean Surface Microplastic Monitoring Methods.Version 1.2. Chiyoda-ku, Tokyo, Japan, Ministry of the Environment Japan, 73pp. DOI: https: //doi.org/10.25607/OBP-867-2

[2] United Nations Environment Programme - UNEP (2020). Monitoring Plastics in Rivers and Lakes: Guidelines for the Harmonization of Methodologies. ISBN 978 92 807-3819-3. Nairobi.

[3] GESAMP (2019). Guidelines for the monitoring and assessment of plastic litter and microplastics in the ocean (eds Kershaw P.J., Turra A. and Galgani F.), London, UK, GESAMP Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection, 130pp. (GESAMP Reports and Studies, No. 99).

[4] Ministry of the Environment Japan (MOEJ) (2021) Guidelines for River Microplastic Monitoring Methods. Tokyo, Japan.

[5] EUROqCHARM Critical Review of methods and protocols for the analysis of nano-, micro-, and micro-plastic in different environmental matrices