BMTA Newsletter BMTA Newsletter - Summer 2020 | Page 16 IDENTIFYING MICROPLASTICS AND NANOPLASTIC POLLUTANTS IN THE ENVIRONMENT Elinor Hughes, technical copywriter at Markes International, Gwaun Elai Medi-Science Campus, Llantrisant, UK. A method called thermal desorption–gas chromatography–mass spectroscopy can be used to identify microplastic and nanoplastic pollutants in the environment. The method is simple to use and enables analysis of nanoplastics down to 0.2 µm in size in less than an hour. The information obtained could also help to identify the source of the micro/nanoplastics and give information on their toxicity. What are microplastics and nanoplastics? Microplastics are plastic fragments less than 5 mm in size (1) and nanoplastics are fragments smaller than 1 µm. There are two types of microplastics – primary and secondary. Primary microplastics are produced intentionally and include fibres used in synthetic textiles, microbeads used in personal care products The and µ-CTE pellets has used three in modes industrial of operation manufacturing. – bulk emissions Secondary microplastics come from larger plastics breaking down testing, due to weathering, surface emissions for example. testing They and permeation include vehicle testing – tyres, shoe soles and packaging. Both types of microplastics accumulate which means and persist it can in be the used environment. for a variety Scientists of investigations. have found them in soil, water and the air, and studies show they have been found in food. As a result, concern over their effect on human health is growing. Instruments such as the Micro-Chamber/Thermal Extractor™ (µ-CTE™) can be used for the rapid screening of VOCs While legislation to tackle plastic waste increases globally, microplastic released pollution from a has material. been overlooked, according to a UN report.(2) This is set to change. In January 2019, ECHA (the European Chemicals Agency) proposed a restriction on the intentional use of microplastics in products placed on the European Union/European Economic Area market to avoid or reduce their release into the environment.(3) The proposal is currently at the consultation phase. A report by the World Health Organisation (WHO), published in the same year, examines evidence related to microplastics in the water cycle (including tap and bottled water and its sources), the potential impact on health after exposure to microplastics and the removal of microplastics during wastewater and drinking water treatments.(4) In the report, the WHO includes recommendations for taking action such as monitoring and managing microplastics in the environment. However, detecting and analysing microplastics in the environment is challenging. The method must be able to detect and distinguish between all the different polymers that can be used to make a plastic, such as polyethylene terephthalate (PET), which is used to make bottles, polyvinyl chloride (PVC), polypropylene (PP), polystyrene (PS), high- and low-density polyethylene (HDPE and LDPE), acrylic, polycarbonate, nylon and fibreglass. Another issue is that additives, such as hardeners, flame retardants and preservatives, are used during the manufacturing process and microplastics can leach these additives into the environment. Also, other compounds can adhere to the surfaces of microplastics. For example, bisphenols have been found on their surfaces, and these have been identified as endocrine disruptors in the human body. (5) So the method needs to detect these too. The method should also be applicable to many sample types (for example water, air, soil, sediment and biota) and be able to detect the smallest nanoplastic particle to the largest microplastic particle. Fast and easy sample preparation is needed to improve throughput and minimise the risk of errors that comes with complicated preparation. The method should provide quantitative results, ideally in a concentration such as µg/L, enabling easier comparison across studies. Techniques currently being tested include spectroscopic methods such as Fourier transform infrared spectroscopy or Raman microscopy, but they can only tell us which types of microplastics are present in a sample, not their concentrations, they are limited to particles greater than 10 µm and involve lengthy sample preparation procedures (hours to days). Tackling the challenges of analysing microplastics To tackle these challenges and to get ahead of regulatory requirements, Eurofins | IPROMA (Castelló, Spain), a company that diagnoses and measures environmental and industrial hygiene aspects, teamed up with Markes International (Llantrisant, UK), a company specialising in the quantification of trace amounts of volatile and semi-volatile compounds by gas chromatography. In their investigation, the team used a chemical analysis technique, coupling thermal desorption with gas chromatography– mass spectroscopy (TD–GC–MS) to identify and measure how much of the plastic Polyethylene Terephthalate (PET) – used to make drinks bottles – had broken down and leached into the drinks.