analytica conference 2020
Bunsen-Kirchhoff Award Lecture: Raman Microspectroscopy for Environmental Analysis
Natalia P. Ivleva, TU München
Raman microspectroscopy (RM) has been recognized as a powerful analytical tool in science and industry. RM is based on the effect of inelastic light scattering by molecules, providing fingerprint spectra with spatial resolution in the µm-range. However, the potential of this technique for the identification, quantification and characterization of different environmental matrices/systems – ranging from microplastics and nanoplastics through atmospheric aerosol particles and (bio)diesel soot to microorganisms and biofilms – has not yet been systematically explored. Furthermore, RM can open the possibility for nondestructive quantitative analysis of the stable-isotope tracers in (in)organic and (micro)biological samples. The sensitivity of the technique can be improved dramatically (by a factor of 103 – 106) when the surface-enhanced Raman scattering (SERS) is employed, e.g. for studies of microbial communities. In this lecture, different application fields for Raman microspectroscopy will be illustrated. The feasibility and limitations of the method will be discussed, with the focus on the analysis of microplastics and nanoplastics (plastic particles in the size range 1 µm – 1 mm and <1 µm, resp.) [1-4] as well as microorganisms and biofilms [5,6]. In particular, the progress in developing automated RM-based analysis, which allows for reliable detection, identification and quantification of (plastic) microparticles, will be shown . Additionally, nanoplastic analysis using online coupling of RM and field-flow fractionation will be discussed. This coupling, enabled by optical tweezers, allows for physical and chemical characterization of plastic and inorganic particles in size range from 200 nm to 5 µm . Furthermore, RM and SERS in combination with the stableisotope approach that has a potential for single-cell sorting will be presented. This powerful tool also enables the nondestructive 2D and 3D characterization of the molecular and isotopic composition of microorganisms on the single-cell level , thus paving the way for in situ investigations of ecophysiology and metabolic functions of microbial communities and analysis of the degradation of environmental pollutants.