IDENTIFICATION OF MICROPLASTICS EXTRACTED FROM THE STOMACHS OF LARGEMOUTH BASS FROM THE MID-ATLANTIC REGION USING TRANSMISSION FTIR MICROSCOPY

For this study microplastics extracted from Largemouth Bass (Micropterus salmoides) stomachs were analyzed. The fish used in the study were from the Potomac and Anacostia rivers (Washington, DC). The purpose of this study was to identify the types of microplastics found in the stomachs of Largemouth Bass in the Potomac and Anacostia rivers. The microplastics were previously extracted from the fish samples by dissecting out stomachs, digesting organic stomach contents material, and density separation followed by filtration for remaining particles. To identify the microplastics a Leica EZ4 HD low magnification microscope, a Nicolet Continuμm FT-IR Microscope (with an ATR accessory), and OMNIC software were used. The plastic extracted from each fish stomach sample was found using the low-magnification microscope and transferred from the filter to a single crystal KBr disk. The FTIR microscope was used to produce infrared spectra for each microplastic through transmission microscopy. For thicker microplastics, the ATR accessory was used to produce infrared spectra. The OMNIC software library database was then used to match each microplastic spectra to known plastic spectra. It was found that there were three to nine microplastics in each fish stomach sample. Rayon was the most common plastic identified and was found in each stomach sample. Other microplastics identified include polyester, cellophane, and polyacrylamide. The majority of microplastics found were fibrous in structure. Other non-plastic materials identified in the extracts include organic material, glass, and salts. Precipitated salt that formed on some microplastics prevented accurate identification of polymer type. A few samples did not have a conclusive match in the library database. The protocol developed in this study can be used for future identification of microplastics using transmission FTIR.