Microplastics analytics: why we should not underestimate the importance of blank controls

Abstract

Recent years have seen considerable scientific attention devoted towards documenting the presence of microplastics (MPs) in environmental samples. Due to omnipresence of environmental microplastics, however, disentangling environmental MPs from sample contamination is a challenge. Hence, the environmental (collection site and laboratory) microplastics contamination of samples during processing is a reality that we must address, in order to generate reproducible and reliable data. Here we investigated published literature and have found that around 1/5 of studies failed to use blank controls in their experiments. Additionally, only 34% of the studies used a controlled air environment for their samples processing (laminar flow, fume hood, closed laboratory, clean room, etc.). In that regard, we have also shown that preparing samples in the fume hood, leads to more microplastics contamination than preparing it in the laboratory bench and the laminar flow. Although it did not completely prevent microplastics contamination, the processing of sample inside the laminar flow is the best option to reduce sample contamination during processing. Overall, we showed that blank controls are a must in microplastics sample preparation, but it is often overlooked by researchers.

A review on microplastics in major European rivers

“…This is particularly relevant in situations when it is necessary to correct for underestimation of microplastics due to low but reproducible recovery rates (Hermsen et al, 2018; Koelmans et al, 2019). In addition to the positive controls, which are designed to minimize influence of internal loss during sample pretreatment, further precautions should be taken to eliminate contamination from external sources (Noonan et al, 2023). Contamination can consist of airborne synthetic components so it is crucial to keep the samples sealed or covered whenever possible both in the field (over the course of sampling and transport) and in the laboratory (during the analysis) (Vandermeersch et al, 2015; Wesch et al, 2016).…”

Microplastics are detected in bull and dog sperm and polystyrene microparticles impair sperm fertilization

“…In order to avoid any potential contamination from airborne or material MPs, all procedures were carried out inside a laminar flow hood, as we have demonstrated it to have the least environmental MP contamination during sample preparation (Noonan et al, 2023). Glass materials were used whenever possible to replace flasks and other apparatuses.…”