Table 2.

Detection techniques for analysing microplastics in environmental samples

Sample	Detection technique	Remarks	References
Fresh water sample	Double digestion followed by Stereomicroscopy	High throughput sample processing Reproducible quantification Double step digestion improved elimination of organic matter	de Carvalho et al. (2021)
Placenta	Raman Micro Spectroscopy	Comparing the obtained spectra with library database, high Quality Index values greater than 80 were found to be satisfactory The pigments in polymers of microplastics were matched and identified using KnowItAll software	Ragusa et al. (2021)
Human colectomy samples	Stereomicroscope Fourier Transform Infra-Red spectrometer	An average of 331 particles/ individual specimen were detected in colon samples Polycarbonates were the most detected polymeric substance and about 96.1% of microplastics were in filamentous or fibrous forms	Ibrahim et al. (2021)
Eviscerated and excised organs of dried fish	Micro Raman Spectroscopy, Field Emission Scanning Electron Microscopy (FESEM) with Energy Dispersive X-ray spectroscopy (EDX)	61 different microplastic like particles were detected from four samples of dried fish Microplastics in fragment form were predominantly found within the fish samples	Karami et al. (2017)
Wastewater sludge	Optical methods: Raman microscopy Transmission spectroscopy, Diffractive Optical Element based sensor, LASER based sensor	Density of microplastics have a major impact on detection techniques being used Developing sensors combining spectroscopic and non-spectroscopic techniques may help in detecting a wide range of microplastics in real time environmental samples	Asamoah et al. (2021)
Environmental samples	Hyperspectral imaging system	A combination of infrared lamp source with macro-photography technique Microplastics even in size of 100 µm were rapidly detected	Zhu et al. (2021)
Underwater samples	Hyperspectral imaging system	Useful for detection of microplastics in underwater lakebed and seabed The spectral image correction and classifiers provides detection even in turbid water conditions	Xie et al. (2021)
Caenorhabditis elegans	Darkfield hyperspectral microscopy	Nanoscale and microscale level microplastics were detected at a wavelength range of visible-near infrared region Visualisation of different microplastics within intestines of live invertebrates was possible using this non-destructive technique	Nigamatzyanova and Fakhrullin (2021)
Trachurus declivis	Fourier Transform Infra-Red spectrometer	Seven plastic particles of different colours were detected in its stomach Micro as well as meso plastic particles were detected with an average size ranging between 4.5 and 10 mm	Jawad et al. (2021)
Edible tissues of shellfishes	Stereomicroscope Fourier Transform Infra-Red spectrometer	Microplastics of fragment shape were the predominant ones in shell fishes Per capita microplastics intake when consuming shellfishes was calculated as 13 ± 58 microplastics per year	Daniel et al. (2021)
Sediments and Mudskipper fish (Periophthalmus waltoni) of mangroves	Raman spectrometer Fourier Transform Infra-Red spectrometer	Sediment samples had about 2657 microplastics and mudskipper fish samples had about 15 microplastic particles Polystyrenes were majorly found in both the samples contributing to about 26% in totally detected microplastics	Maghsodian et al. (2021)
Coral reefs of Java Sea	Attenuated total reflectance micro–Fourier Transform Infra-Red spectroscopy	Polypropylene microplastics were predominant among the samples Secondary microplastics were majorly identified in coral samples in which microplastics in fibrous form accounted for about 98%	Utami et al. (2021)
Marine sediment samples of Rameshwaram island	Fourier Transform Infra-Red spectroscopy attenuated combined with attenuated total reflectance	Polypropylene and polyvinylchloride microplastics were the most and the least detected polymeric substances Anthropogenic sources like fishing and tourism activities contributed to release of microplastics	Vidyasakar et al. (2018)