Centres Científics i Tecnològics UB



Improvements in the characterization of microplastics

In recent months, at the Molecular Spectroscopy Unit we have continued to improve the method for the analysis of microplastics by Infrared Spectroscopy in various matrices.

In any study of microplastics in animals, food, soil, sand, water .... it is very important to be able to isolate them from their matrix, which is often complex and requires enzymatic or chemical digestion, chemical or flotation, digestion,... until reaching the filtration process where these fibers and particles are clean on a dry support.

The usual filters of Teflon, polycarbonate, alumina,... interfere with the infrared spectrum during the analysis. In order to perform a good characterization of the sample, it was therefore necessary to remove the microplastics from the filter and place them on a support that would allow their analysis by transmission or reflection. The only supports that allow this analysis are gold or aluminum by reflection, and calcium fluoride by transmission.

This process required a long time and expertise to be able to manipulate these particles, that often have dimensions of up to 15 microns, and to place them as close together as possible on the mentioned supports to later be able to acquire a map with the image detector and to characterize the particles.

After performing tests and having consulted different bibliographic references, a 13mm filtration equipment was purchased from the Molecular Spectroscopy Unit, which allows the filtering of smaller microplastics. Similarly, it was decided to work with silicon filters. Filters of this material can be used for transmission or reflection, do not interfere with the infrared spectrum and are recyclable, thus contributing to the reduction of waste products in the laboratory.

This method allows to directly analyze the surface where the particles and fibers have filtered.