Microplastics analysis accreditation helps raise standards of practice

As microplastics analysis continues to develop and mature, one leading Australian laboratory has been working on establishing a set of methodologies and practices to help push the field into a new era of standardisation. 

In 2019, Eurofins Environment Testing Australia opened their commercial microplastic laboratory in Melbourne. In November last year, the laboratory was the first facility to be awarded NATA ISO/IEC17025 accreditation in Australia for the analysis of microplastics in potable water.

Eurofins Technical Specialist Dr Julia Jaeger said the lab is very proud to receive the accreditation, which is the result of years of work to improve microplastics analysis methodologies and practices within their laboratory.

“We started our journey about four years ago, when we opened our microplastics laboratory at our Melbourne Campus. At that time, there weren’t any standard methods and we had to use peer reviewed papers and other published methods.” she said.

“Now, we do have some standard methods, but they are only for analysing microplastics in drinking water.”

In the field there are various analysis techniques deployed ranging from microscopy to spectroscopy (FTIR, LDIR and Raman), thermal analysis (thermal desorption gas chromatography (TD-GC/MS) and pyrolysis gas chromatography (PYR GC/MS).

All these techniques have their own capabilities. The main differences are the results produced: microscopy and spectroscopy analyse the particles individually, whereas the thermal analysis techniques report the amount of microplastics as a concentration. This dilemma makes the comparison of studies very difficult.

Currently, Eurofins’ microplastics laboratory uses spectroscopy to analyse microplastics but are in the process of implementing PYR GC/MS. The Agilent 8700 Laser Direct Infrared Chemical Imaging System (LDIR) is used to enumerate, size and chemically analyse microplastic particles between 20 µm and 5000 µm for the nine most common plastics.

“We are scanning every single particle and performing a chemical analysis, as well as sizing the particle,” Jaeger said.

“With drinking water, there has been a huge discussion about this because some studies weren’t finding microplastics in samples. But size and analysis technique is really important.

“We keep finding plenty of microplastics because we are going to a much lower size range. Some studies find little or anything because they are not looking at the lower range.”
In our experience most of the particles we find especially in waters are in the size range between 20 and 100 µm. The size of the particles is very important for toxicological studies. The smaller the particles are, the more toxic they are to humans – as the small particles can easily dislocate within the body.

Jaeger said the issue we have with the science of microplastics analysis is that we don’t have any quick answers – it’s a new field of inquiry into a very complex problem and developing methods and practices that everyone agrees on takes time.

“We’re still not there yet in terms of having a standardised approach to how we analyse microplastics. We have limited referenced methods and often disagree on methods, too,” she said.

“It’s not the easiest field to work within, but that’s why this accreditation is so important. For us, quality assurance and control is important in terms of working towards establishing standards.”

Raising the bar

Jaeger important to ensure samples are not contaminated during the analysis, Jaeger said, which – in the case of microplastics – can be much more difficult than the layperson might expect as plastics are omnipresent.

“Our microplastics lab is fully enclosed. There is a changing room moving into and out of the lab. And contaminating a lab is as simple as wearing a lab coat made of a material with polymer in it, we wear lab coats made from cotton,” she said.

“We keep the lab at positive pressure and the inflowing air is HEPA filtered. We clean the laboratory every evening. We try to minimise the use of equipment made from plastic overall and use mostly glassware. This is cleaned in a 450 °C furnace or washed with microplastic-free water. All the reagents that we use are filtered and quality controlled before they are used.

"For all the materials we still can’t replace with glass or metal we keep a plastics record. We take monthly air blanks, to monitor the air in the laboratory and to ensure the air in the lab is clean.”

“It is impossible to eliminate background contamination – but we try our utmost to keep it as low as possible. However, there are some labs that don't control their background at all.”

Eurofins’ microplastics laboratory deploys quality control samples, Jaeger said, which still isn’t a common practice in the field: “Every tenth sample is spiked with a known amount of Polyethylene beads at two different sizes and the recovery is calculated”.

“We also process regent blank samples with every sample batch. This is all part of our analytical report. We have also brought in reference materials for all the nine polymers we are reporting and have verified our library against those materials. However, as there are very limited reference materials on the market,” she said.

Initially, we started with analysing potable water samples and over the years have moved to more complex matrices as sand/sediment soils, biosolids and biota. These more complex matrices are more difficult to analyse as the microplastics need to be separated from the matrix.”

“We have worked on several clean up techniques that we have taken from peer reviewed papers or published methods and established and perfected our own methods over the years to help us prepare samples prior to analysis. With every method development monitoring our quality control samples has been imperative.

“All of this has been trial and error and working through different ways of improving our practices and we are learning every day. This is a very different approach to other parts of our business where well-defined EPA methods are the bases of methods.”

Future focus

In terms of where microplastic analysis is headed, Jaeger said there is no shortage of avenues and questions that are yet to be explored as the field develops.

“We have utilities with monitoring plans that send us samples every year to analyse. Some drinking water guidelines, as in California and Europe, are exploring whether to establish requirements around microplastic concentrations. So, we expect there will be more of that work in future,” she said.

“From utilities, the most interest has been around wastewater, including influent, effluent and biosolids. Where biosolids are the most contaminated samples. This is very concerning especially if they are intended to be used as fertiliser. But we’ve also had enquiries about microplastic analysis in recycled water.

“There is a push in the field to get our hands on reference materials that look at weathered microplastics, which are microplastics that have been exposed to the environment. Once they are out in the open, microplastics can change their chemical structure.

Despite Eurofins efforts, Jaeger said there is also plenty of work to be done globally to get everyone on the same page in terms of what a microplastics laboratory should look like and what kind of quality control is required.

“Recently, a major scientific journal has refused to publish any studies on microplastics that haven't used certain methods of analysis, as well as accepted quality control and blank procedures. So, this area is still shifting and changing, and standards are still being negotiated,” she said.

Jaeger said keeping abreast of new insights via networks is very important.

“Within Eurofins there is a network of five laboratories on three different continents that work very closely in order to improve the field through their collaboration. But also, the connections beyond and very important,” she said.

“People see macroplastics or large microplastics on the beach and see this as an issue. But there are much more particles that we can’t see. Recycling is one avenue, but it doesn't really solve the issue of microplastics or nanoplastics. And the extend of the problem is not fully understood yet.

“That's why we are trying to validate our methods. We are very proud of the accreditation. It’s a step in the right direction.”