Beta-carotene-A possible biomarker in the Martian evaporitic environment: Raman micro-spectroscopic study
Abstract
Raman micro-spectroscopy was tested as a nondestructive method of determining the presence of beta-carotene in experimentally prepared evaporitic matrices. Samples prepared by mixing beta-carotene with powdered gypsum, halite and epsomite were analyzed using a 785 nm excitation source.
Various concentrations of beta-carotene in the matrices were investigated to determine the lowest beta-carotene content detectable by Raman microspectroscopy. We were able to obtain a clear beta-carotene signal at the 10 mg kg(-1) concentration level-the number of registered beta-carotene Raman bands differed depending on the particular mineral matrix.
Spectral signatures of beta-carotene were detected even when analyzing samples containing 1 mg kg(-1) of this molecule. The 10-100 mg kg(-1) of beta-carotene in mineral matrices (halite, epsomite) was detected when analyzed through the monocrystal of gypsum and epsomite, respectively.
These results will aid both in-situ analyses on Mars and sample analyses on Earth.