A novel high-throughput analytical method to quantify microplastics in water by flow cytometry

Abstract

Microplastics (MPs) are pervasive contaminants with unclear toxicological impacts. Current research on MP pollution relies on low-throughput methodologies, which are time-consuming and cannot directly measure MP concentration in suspensions. This study presents a qualitative and quantitative flow cytometry-based method for analysing MPs in water, offering a faster and more sustainable alternative. The method involves density separation to remove interfering particles, UV irradiation to eliminate microorganisms, and filtration to remove particles above 100 µm. The sensitivity of the method for different types of MPs, such as polystyrene (PS), polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), and polyamide (PA) microbeads, ranges from 2 µg/L to 1 mg/L. For these MPs, good linearity was found in matrix-matched calibration where the most concentrated standard was 5 mg/L (R2 0.9820–0.9989) although the linear range can be larger (e.g. 42 mg MP/L for PS microbeads). The repeatability and reproducibility of the method for the model PS MP were <17.0% and 8.5%, respectively. The sample treatment method consisting of density separation and UV pretreatment, when carried out independently, led to 95.0% and 93.4% recoveries. The overall trueness of the optimized method for various sizes and compositions of microbeads is about 97%, according to validation supported by microscopy analysis. This method can substitute the traditional quantitative analytical approach based on counting microbeads with microscopy

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