Methods and challenges in the detection of microplastics and nanoplastics: a mini-review

Microplastics (MPs) and nanoplastics (NPs) constitute a newly recognized class of contaminants of emerging concern in air, soil, water and food, causing unavoidable exposure to humans and animals. Detection, identification and quantification of MPs and NPs in environmental matrices and biota is challenging due to the analytes' small size, random morphology, polymeric diversity, applied coatings and vast surface areas which attract chemical and microbial sorbates. This mini-review explores strengths and weaknesses of analytical methods commonly used for MP and NP identification and quantification, including stereomicroscopy, SEM, Fourier transform infrared spectroscopy, Raman spectroscopy, flow cytometry and mass spectrometry techniques including matrix-assisted laser desorption/ionization time-of-flight, pyrolysis gas chromatography–mass spectrometry and liquid chromatography–tandem mass spectrometry. Analytical challenges involved in precise MP/NP detection have been identified and recommendations have been provided to ensure data quality addressing common data quality concerns, including the difficulty of obtaining irrefutable proof that detected polymers originated from the sample as opposed to sample contamination during sample acquisition, sample processing and analysis.