Sampling, separation, and characterization methodology for quantification of microplastic from the environment

As millions of tonnes of plastics wind up in the environment, plastic pollution is a severe issue that worsens with time. In addition to primary plastic particles, large plastic items are fragmented due to ultraviolet radiation, degradation, and other environmental causes, resulting in minuscule compounds, known as microplastics or nanoplastics. They adsorb hazardous contaminants or easily get absorbed by organisms, for example, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, or heavy metals get adhered to microplastic surfaces due to their tiny size and large surface area. Studies on their toxicity and environmental fate are crucial in light of these challenges, but their effectiveness depends on sampling procedure, sample preparation, characterization, analysis, and quantification techniques. The standard methods for the characterization of microplastics are performed using Fourier transform infrared resonance, Raman Spectroscopy, and pyrolysis Gas Chromatography Mass Spectrometry. Unfortunately, none of these techniques can achieve in-situ non-invasive characterization. These processes are complex, non-uniform across the studies, and different for specific sampling domains such as soil/sediment, surface water or groundwater, biota, and atmosphere. Thus, the current study highlights a specific methodology being used for sampling, sample preparation, characterization, and analysis from solid, aqueous, air, or biota samples. This review paper also specifies the characterization tool and quantification of microplastic concentration and types in the different environmental samples. Future studies on microplastics should prioritize the development of standardized sampling protocols to ensure comparability across diverse ecosystems. Additionally, employing advanced analytical techniques and collaborating across interdisciplinary fields can enhance the accuracy and reliability of microplastic separation and quantification methods.