Current techniques for identifying, quantifying, and characterizing micro and nanoplastics with emphasis on strengths, limitations, and challenges

Microplastic and nanoplastic (MNP) contamination has infiltrated nearly every facet of life, including food, water, air, and soil. The persistence of MNPs within different matrices poses a significant environmental and human health risk, underscoring the necessity for standardised methods to detect, characterise, identify, and quantify these emerging pollutants of concern. Traditional detection methods, such as visual inspection and gas chromatography, have limitations and are thus unsuitable for rapid, repetitive analyses. As such, advanced techniques like Fourier-transform infrared (FTIR) spectroscopy, hyperspectral imaging, and artificial intelligence (AI) interfaces are becoming favoured. FTIR spectroscopy is the most popular method used today to identify and quantify MNPs. Furthermore, recent advancements in micro-FTIR (μ-FTIR)-AI image processing have enabled the semi-automation of MNP identification concentrated on different filter membranes without pre-sorting. Integrating AI tools in combination with μ-FTIR analysis can significantly boost its functionality as automated image processing facilitates quicker identification and quantification of MNPs. Overall, challenges remain in MNP detection due to plastic particle size constraints, contamination from organic matter, and a lack of standardised protocols, complicating the identification and quantification of these pollutants in environmental matrices and biological samples. Despite extensive research, there remains a pressing need for reliable, cost-effective analytical techniques. Moreover, establishing uniform definitions, characterisation methods, sampling techniques, risk assessment frameworks, and regulatory guidelines for MNPs is imperative for their effective management and regulation.