Rapid contamination during storage of carbonaceous chondrites prepared for micro FTIR measurements

Organic contamination (similar to 2965 and similar to 1260 cm(-1) peaks) was found on Tagish Lake (C2) and Murchison (CM2) carbonaceous chondrites containing abundant hydrous minerals by Fourier transform infrared (FTIR) microspectroscopy oil the samples pressed on Al plates. On the other hand, anhydrous chondrite (Moss, CO3) was not contaminated. This contamination occurred within one day of storage, when the samples pressed on Al were stored within containers including silicone rubber mats. Volatile molecules having similar peaks to the contaminants were detected by long-path gas cell FTIR measurements for the silicone rubber mat. Rapid adsorption of the volatile contaminants also Occurred when silica gel and hydrous minerals such as serpentine were stored in containers including silicone rubber, silicone grease, or adhesive tape. However, they did not show any contamination when stored in glass and polystyrene containers without these compounds. Therefore, precious astronomical samples such as meteorites, interplanetary dust particles (IDPs), and mission-returned samples from cornets, asteroids, and Mars, should be measured by micro FTIR within one day of storage in glass containers without silicone rubber, silicone grease, or adhesive tape.