Fast screening of carotenoids of gypsum endoliths using portable Raman spectrometer (Messinian gypsum, Sicily)

We tested the potential of a portable Raman spectrometer-RaPort (G) by EnSpectr with a 532-nm laser for use in field detection of biomarkers of endolithic colonization in gypsum. This study extends our previous research on gypsum endolithic colonies using laboratory Raman microspectrometer (514.5- and 785-nm lasers). In the current study, variously coloured layers were found and screened separately on the outcrop under natural conditions. In the recorded Raman spectra, stretching vibrations of carotenoids were observed-nu(1) (C(sic)C) around 1,513 cm(-1), and nu(2) (C-C) around 1,154 cm(-1), as well as the feature at around 1,005 cm(-1). The exact identification of different carotenoids by portable Raman spectrometer is limited. Nevertheless, the portable Raman spectrometer allowed fast and in situ detection of carotenoids of variously pigmented gypsum endolithic zones. Application of miniature Raman instruments is important in the context of forthcoming astrobiological missions to Mars (Exomars and Mars 2020).