Methods used in the identification and quantification of micro(nano)plastics from water environments

Micro(nano)plastics (MNPs) pollution, which has currently become a serious environmental problem, poses a great risk to ecosystem health and biodiversity. The adverse effects of MNPs in different characteristics on organismal homeostasis are intensively studied due to their considerable threats to ecology and human/public health, since they have been identified in human blood, placenta and breast milk. To date, many studies have been carried out on MNPs, and remarkable results have been reported on their diversity, distribution, origins and their influences at the cellular level, to name a few. The literature suggests that the extent of the risk caused by MNPs is increasing significantly every year, making it even more critical and urgent to combat MNPs pollution in the environment including aquatic environments. Therefore, it is highly important to identify, quantify and monitor MNPs, especially in the water environments since it represents one of the main transportation routes of MNPs. In this review, we provide a broad and critical overview of the different methods, such as Fourier transform infrared spectroscopy (FT–IR), Raman spectroscopy, transmission/scanning electron microscopy (TEM/SEM), and gas chromatography–mass spectrometry (GC–MS), currently used in the identification and quantification of MNPs, especially in aquatic environments such as seawater and marine sediments. Each of these previous methodologies has its own unique advantages and limitations; besides, there is no validated and standardized analytical method for MNPs determination, implying that more than one method or the combinations of different methodologies are required to obtain accurate data at the current state. Moreover, considering the presence of high variability of data among different methods, more research is needed to develop a universal analytical protocol to increase reproducibility and robustness of the findings on MNPs contamination in the environment, in order to increase the credibility and impact of the field.