Coumarin 6 staining method to detect microplastics

Microplastics have contaminated the ocean in large quantities and are widely distributed throughout the world. Thus, our understanding of the concentration of microplastics in various environments should be increased. However, current methods to detect microplastics require considerable effort and expensive equipment. In this study, we developed a fluorescence staining technique using coumarin 6 and examined its effectiveness. A mixture of acetone and ethanol was used as the solvent, and 10 different types of plastics were able to be stained with coumarin 6. The fluorescence peak for coumarin 6 staining was approximately 500 nm for each plastic type. The optimal immersion time and coumarin 6 concentration for staining were determined to be 60 min and 1 mg L-1, respectively. Using this technique, we were able to stain all of the microplastics obtained from samples collected in Tokyo Bay seawater.

Automated summary

Microplastics are a significant ocean pollutant and are widely spread across the globe. Hence, there is a need to enhance our understanding of microplastic levels in different environments. However, current detection methods for microplastics are labor-intensive and expensive. In this study, we developed a fluorescence staining technique using coumarin 6 and evaluated its efficacy. By using a mixture of acetone and ethanol as a solvent, we successfully stained 10 different types of plastics with coumarin 6. The fluorescence peak for coumarin 6 staining was around 500 nm for each plastic type. The optimal immersion time and coumarin 6 concentration for staining were found to be 60 min and 1 mg L-1, respectively. Using this technique, we were able to stain all microplastic samples collected from seawater in Tokyo Bay.