Feasibility of Raman and FTIR spectroscopy for direct microplastic search in the human milk samples: Comparative qualitative study

Abstract

The ubiquitous presence of microplastic particles encompasses the human tissues and secreta. Unfortunately, the complex biological matrix hampers the proper polymer identification, and harsh purification protocols damage the microplastic particles (MPs), change the specimens frequently used and needed for additional diagnostics, and bias the final result. Moreover, purification of human milk samples is sometimes impossible, as the samples can not be subjected to any chemical pretreatment. Thus, this paper aims to check the feasibility of complementary spectral approaches, namely FTIR (Fourier-transform infrared) and Raman spectroscopy, to the fast scanning of selected MPs presence, in particular polyethylene (PE), and polystyrene (PS), in human milk samples without any previous purification to prevent the change of matrix. Although the proposed approach cannot be used for the quantitative measurement of MPs concentration or the detection of low-size fractions, it is a valuable tool for the preliminary screening of numerous population samples, and some preliminary conclusions can be drawn. One may easily detect the most common MPs and observe their eco-corona. Mapping mode is beneficial for scanning large areas. Furthermore, the spectral methods turned out to be efficient in the milk itself diagnosis, for instance, the monitoring of the fat content. The results were placed in the context of the ongoing broad discussion about MPs interaction with the human body and several possible impact mechanisms.