Micro Plastic Analysis

Microplastics are synthetic, high molecular weight compounds that have been micronized into plastic particles smaller than 5 mm. Such materials have a low biodegradation rate and therefore mostly remain in the environment, adversely affecting the human body, which is the final consumer in the food chain.

The chemical composition of environmental microplastics is diverse and includes polymers such as polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate, polyvinyl chloride, and polyvinyl alcohol. Microplastics can be found as pieces, films, fibers, and foam.

People are mainly exposed to microplastics through the use of various plastic products, e.g. plastic packaging containers, decomposing plastic materials, fishing nets, textiles and personal hygiene products, and through exposure to paint chips that leak into the environment (i.e. air, water, seawater and soil). Therefore, people can be exposed to microplastics through direct ingestion, direct contact and inhalation.

Microplastics are ubiquitous and humans are exposed to microplastics through various routes. Various exposure and toxicity assessments are needed to assess the toxicity and adverse effects of such exposure in humans.

Microplastics are so small that they are nearly impossible to collect once they are released into the ecosystem. As a result, countries around the world are enacting legislation regarding primary microplastics. For example, countries in the European Union are taking various measures to recycle plastics, develop biodegradable plastics, remove harmful substances from plastics, and prevent marine litter.

The standard “ISO 24187 Principles for the analysis of microplastics in the environment” published by the International Organization for Standardization (ISO) describes the principles to be followed in the analysis of microplastics in various environmental matrices. These include the unique particle size classification of plastics, sampling, sample preparation and the use of specific apparatus for determining representative sample quantities.

The purpose of this standard is to specify minimum requirements until specific standards are available for different situations. This is important to ensure that the development of specific standards is done on a consistent basis and that comparison or correlation of results is possible. However, this standard does not include requirements for follow-up actions.

For the purposes of this standard, the following definitions apply in addition to the terms and definitions given in “ISO 472 Plastics - Vocabulary”:

• Large microplastic is any solid plastic particle that is insoluble in water with a size between 1 mm and 5 mm. Microplastics can take on a variety of shapes. Generally, a large microplastic object represents an item composed of plastics or a part of an end-user product or related item.
• A microplastic is any water-insoluble solid plastic particle with a size between 1 µm and 1 mm. A primary microplastic object represents a particle intentionally added to end-user products, such as cosmetics, coatings, and paints. A secondary microplastic object may also occur as part of the item in question. Microplastics come in regular and irregular shapes. The size identified is related to the longest dimension of the particle.
• Additives are substances used to process plastics or to modify their end-use properties. Important additives such as fillers or reinforced materials, plasticizers and flame retardants are defined in the ISO 1043 standard.

Microplastics is a term that comes with different physical and chemical properties, such as shape, size (range), type of polymer, presence of additives, presence of fillers, degradation status, etc. The amount of microplastics in a given matrix can be measured in different ways, i.e. as number (particles) or mass content or ratio to the amount, for example.

A schematic representation of the interdependencies of microplastic analysis is shown in the figure given in the standard.

All analytical steps (sampling, sample preparation, detection) should be carried out under plastic-free or low-plastic working conditions. This includes avoiding standard plastic products (e.g. tubes, containers). Contamination, especially cross-contamination, should be prevented, and the user should avoid using plastic equipment wherever possible. Instead, alternatives made of metal, glass or ceramic should be used. As an exception and after being proven by testing, types of plastic that cannot be detected or evaluated can also be used. Care should be taken to ensure that personal protective equipment, e.g. lab coats or gloves, are made of non-synthetic material or materials that do not interfere with the analysis. Recovery tests should be performed for each analytical step.

If possible, samples should be processed in laminar flow boxes in the laboratory or in clean rooms, especially during the preparation of samples and during the determination of particle counts. It should be determined in advance whether the samples need to be sanitized. Sterilization is a standard recommendation for the analysis of dry samples from wastewater, sewage sludge and organic waste. Various methods can be applied, but each has a specific effect on the integrity of microplastic particles in the sample:

• Steam sterilization: Risk of melting microplastics (e.g. PE, PP).
• Radiation sterilization (gamma, beta radiation, UV radiation): Risk of destruction of the polymer structure (separation of polymer chains and oxidation).
• Chemical sterilization: Risk of chemical modification of the polymer structure or the surface of the particles.

Relevant information on measurement conditions and control processes (quality assessment and quality control), including all analytical steps, should be recorded. For general quality control measures in laboratories, the ISO/IEC 17025 standard should be followed, and for comparative tests, the ISO 13528 standard should be followed.

Our organization has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. Among the numerous test, measurement, analysis and evaluation studies provided for businesses in various sectors, there are also micro plastic analysis services.