The combination of spectroscopy, microscopy, and profilometry methods for the physical and chemical characterization of environmentally relevant microplastics

Abstract

Environmental pollution related to microplastics (MPs) is a growing concern across the globe.

Critical Assessment of Analytical Methods for the Harmonized and Cost-Efficient Analysis of Microplastics

“…Attenuated total reflection FT-IR 16,29,54,59,83–85,87,88,91–93,95,99–149,154,157,158,162–165,215,219,…”

“…µFT-IR Measurements of Selected Particles and Imaging Techniques . Using a microscopic coupled ATR, 29,154,157,158,162–165,215,219,220 reflection 53,167,188,196,199,200,205,224,231 and transmission FT-IR 51,155,172,178,180,182,186,190,191,197 can be applied on particles sorted onto slides, 29,187 compression cells, 29,173,181,198,215 windows, 209 meshes, 232 or various filter membranes (see below). By visual selection of the particles, a measurement can be performed with relative ease.…”

“…In the reviewed studies, FT-IR was performed either by measuring single particles, 16,54,59, via handheld FT-IR, 137,151 by a fiber optic, 152 by using mFT-IR, 18,29,35,42,51,78,100, by applying both techniques on separate instruments, 40,50,53,66,73,78,[213][214][215][216][217][218][219][220][221][222][223][224] or referenced to other publications. 225 Larger single particles were ground with potassium bromide (KBr) for transmission measurements, targeted via diffuse reflection, or by ATR measurements.…”

“…35 Typically, such a size fractionation was performed at 500 mm. 35,40,[71][72][73][74]161,203,213 Attenuated total reflection FT-IR 16,29,54,59,[83][84][85]87,88,[91][92][93]95,154,157,158,[162][163][164][165]215,219,220 was used by 58% of the overall studies, especially for larger particles, as it is most cost efficient, since no sample preparation (e.g., transmission) or difficult mathematical corrections (e.g., pure or diffuse reflection 196 ) are required. Other than the initial cost of the ATR unit, only a cleaning solution for the crystal is necessary, while for transmission and reflection more consumables may be required.…”

“…Untreated samples can be investigated using variable pressure SEM (VPSEM), which have a chamber pressure of 1 Pa to 2000 Pa and use atmospheric gas or water vapor. 29,306 Both types are currently used in MP research, either for surface studies, particle investigation, 101,103,110,174,189,206,208,219,223 weathering, 142 as well as the influence of artificial weathering or biodegradation 169,307 and material identification 29,93,98,143,154,167,205,308 with the help of an energy dispersive X-ray spectrometer (EDS). EDS is an extra module connected to the setup and considered a combined technique, which measures the X-ray radiation emitted from the surface during beam-surface interaction.…”