Fluorescent Tagging of Polymer Particles with PBN for the Detection of Microplastics in Personal Care Goods

Abstract

Objectives : Plastic pollution has been aggravated due to the massive use of disposable products and single-use face masks since the coronavirus disease (COVID-19) pandemic. There is growing interest regarding detection and identification of plastic pollution in daily life. The aim of this study is (1) to investigate suitability of a fluorescent labelling method for the detection of polymers, (2) to detect microplastics in personal care goods, and (3) to identify the detected plastic particles.Methods : In order to detect plastic particles in real samples, a 1-pyrenebutyric acid N-hydroxysuccinimidyl ester (PBN) fluorophore was used as a dye for staining plastic particles. First, the capability of PBN was evaluated by staining a model polymer of polyethylene (PE) particles, and its desorption and photobleaching was also investigated. Using the optimum staining condition, microplastics were detected in a laboratory-controlled sample and commercially available products, specifically in cleansers, scrubs, and toothpastes. Finally, the detected microplastics were identified using an attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR) analysis.Results and Discussion : The PE particles fluoresced blue light after being stained with PBN at a concentration of 100 μg/mL for 3-5 min without post treatments (e.g., fixation and drying), but the particles should be detected within 24 h due to the photobleaching of PBN. The desorption of PBN fluorophore occurred when the stained PE particles were washed with 25% acetone rather than rinse-off with deionized (DI) water. All of the tested personal care goods contained plastic particles and various sizes and shapes (e.g., spherical, rounded, and irregular shapes) of particles were found in different types and brands of products. The detected particles were identified as PE, polypropylene (PP), polycarbonate (PC), ethylene vinyl acetate (EVA), polystyrene (PS), and polyvinyl chloride (PVC) polymers.Conclusions : The PBN was shown to effectively stain polymer particles and it allowed visual identification of microplastics in personal care goods. Various types and sizes of polymers were included into the commercially available products as ingredients, indicating a primary source of plastic pollution in aquatic environment.