Testing a portable Raman instrument: the detection of biomarkers in gypsum powdered matrix under gypsum crystals

In this study the possibility to detect biomarkers in experimentally prepared evaporitic matrices using a portable Raman instrument was estimated. Testing of the instrument was carried-out under the Alpine conditions outdoors at a low ambient temperature of -10 °C and at an altitude of 2860 m (Pitztal, Austria). Amino acids glycine and l-alanine, nucleo bases thymine and adenine, and metabolite urea were the organics mixed with gypsum powder. In this step it was shown that portable Raman spectroscopic instrumentation is capable of detecting biomarkers in complex samples in a host geological matrix. Such detection is possible even when the laser beam was focussed through the gypsum crystals 3-9 mm thick. For exobiology areas, this is an important fact, because life and/or related biomolecules are likely to be found in cavities under the surface of partially transparent evaporitic minerals that provide them a shelter from the hostile surrounding environment. For influencing the intensity of Raman bands the thickness of covering crystals is not as important as is the actual concentration of the biomarkers. This work and similar experiments serve for better evaluation of Raman spectroscopy as a method for future planetary exploration mission adoption.