Microplastics are often invisible to the naked eye due to their small size, but they significantly influence human health and the environment. Furthermore, detecting and quantifying microplastics is a significant challenge in studying these plastic particles.
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One of the methods used to assess microplastics, specifically microplastic exposure, is thermal analysis. This article explores the use of thermal analysis in assessing microplastics and its implications for microplastic exposure.
How Microplastics Pollute the Environment
Since the start of commercial plastic manufacture, society has become increasingly dependent on plastics. Global demand has been stoked by its adaptability, stability, lightweight, and affordable manufacturing costs. The majority of plastics are used and dumped on land at first. However, it is anticipated that by 2030, the number of microplastics in specific marine compartments will have doubled, increasing marine pollution.
Numerous processes, such as the disintegration of bigger plastic objects, the shedding of synthetic nanofibers, and the discharge of microbeads from personal care products, release microplastics into the environment.
Animals and humans may consume these microplastics causing several health issues, including inflammation, liver damage, and alterations in gut flora. Therefore, understanding plastic composition, physical forms, usage, transit, and fragmentation into microplastics and nanoplastics is essential to finding solutions to this worldwide environmental challenge.
Analytical Techniques for Microplastic Detection
Very few analytical techniques are available to detect microplastics and nanoplastics in various environmental matrices. They lack a set of uniform criteria that would allow for simple comparisons between multiple studies and monitoring accuracy. Therefore, there is a pressing need for set standard analytical techniques to further the knowledge of environmental microplastic contamination.
The lack of standardized analytical processes and common standard parameters for microplastic analysis results in an underestimation of their abundance in the environment. Consequently, it is challenging to quantify levels, compare data from various matrices, and estimate the organisms' exposure to microplastics. Therefore, various alternative procedures and analytical techniques have been developed to separate microplastics from environmental matrices and determine their polymeric composition.
Fourier Transform Infrared (FTIR)-based Techniques
FTIR-based non-destructive techniques have been around for a long time. However, they are not effective for microparticles or nanoparticles, and detection depends on the type of environment matrix. Additionally, it takes time to analyze the gathered spectra since comparing each spectrum for each micro(nano)plastic often becomes necessary.
The development of extra bands in the micro(nano)plastics spectra due to aging brought on by weathering processes or biofouling may lead to incorrect interpretations of the polymeric composition of objects.
Furthermore, as FTIR and micro-FTIR analyses cannot detect tiny nanostructures, it is impossible to get a complete picture of plastic contamination. Microscopy, in combination with Raman Spectroscopy, is another viable approach to detect particles smaller than one millimeter in size. However, interferences brought on by impurities' autofluorescence make it difficult to recognize them.
Thermal Analysis for Assessing Microplastic Exposure
Thermal analysis is a group of analytical methods used to examine materials' physical and chemical characteristics as their temperature varies. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) are the two methods of thermal analysis most often utilized.
Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC)
DSC is a method that gauges the variance in heat flow when a sample and a reference material are heated or cooled. The method may be used to gauge a material's melting point, glass transition temperature, and crystallization temperature.
TGA is a method that weighs a sample while it is being heated or cooled. The method may be used to gauge a material's thermal stability and decomposition temperature.
Microplastic exposure can be evaluated in several ways using thermal analysis. Identification of the different forms of plastic contained in a sample is one of the most often used thermal analysis techniques in the study of microplastics.
The thermal characteristics of various plastic types may be utilized to distinguish between the different plastics present in a sample. DSC, for instance, may be used to determine a sample's glass transition temperature, which can be used to determine the kind of microplastic it contains. Similarly, TGA can be used to measure the decomposition temperature of a sample, which can also be used to identify the type of plastic present.
Quantifying the plastic in a sample is another way thermal analysis is used in microplastic research. The quantity of plastic contained in a sample may be determined using TGA by measuring its weight loss when heated. The degradation of plastics can also be studied via thermal analysis.
Limitations of Thermal Analysis
Thermal analysis has certain limits while being a valuable method for evaluating microplastics. One of its key drawbacks is that it can only be used to research the physical and chemical characteristics of plastics. The biological consequences of microplastic exposure cannot be assessed using it. Furthermore, the thermal analysis may not be able to pick up extremely tiny particles like nanoplastics.
Thermal analysis is still a valuable technique in the research of microplastics despite these drawbacks. It may provide insightful data on the kinds and quantities of plastics found in the environment, which can be used to guide policies and rules targeted at minimizing microplastic pollution.
Future Prospects
As a relatively new area of research, there is still much to learn about how exposure to microplastics affects the environment and human health. To better comprehend the causes, mechanisms, and possible impacts of plastic particle contamination on human and environmental health, further study in the field of nanotechnology is required, which may include developing novel nanosensors and new methods and techniques.
More methodologies will be required in addition to thermal studies to completely comprehend the effects of micro and nanoplastics. Studies on the ecological impacts of microplastics on aquatic and terrestrial ecosystems as well as the possible health implications of microplastic exposure may fall under this category.
References and Further Reading
Hale, R. C., Seeley, M. E., La Guardia, M. J., Mai, L., & Zeng, E. Y. (2020). A global perspective on microplastics. Journal of Geophysical Research: Oceans. https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2018JC014719
Mansa, R., & Zou, S (2021) Thermogravimetric analysis of microplastics: A mini review. Environmental Advances. https://www.sciencedirect.com/science/article/pii/S2666765721000880
Parolini, M., Ortenzi, M. A., Morelli, C., & Gianotti, V. (2021). Emerging use of thermal analysis in the assessment of micro (nano) plastics exposure. Current Opinion in Toxicology. https://www.sciencedirect.com/science/article/abs/pii/S2468202021000486
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