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June 14 @ 1:00 pm - 2:00 pm MDT
Title: Investigating Soluble Organic Compounds in Aqueously Altered Carbonaceous Chondrites by Ultrahigh Resolution Orbitrap Mass Spectrometry
Program: Master of Science in Chemistry
Advisor: Dr. Michael Callahan, Chemistry and Biochemistry
Committee Members: Dr. Adam Colson, Chemistry and Biochemistry, and Dr. Dale Russell, Chemistry and Biochemistry
Most meteorites are fragments from main-belt asteroids and contain extremely primitive materials that have preserved a compositional record of the early Solar System. After the formation of their parent bodies, carbonaceous chondrites experienced secondary modification from thermal metamorphism and/or aqueous alteration. Secondary processing likely influenced the synthesis and/or final composition of organic compounds in parent bodies; thus, these effects may be elucidated from the study of different meteorites. Although the role of aqueous alteration has been investigated for a few specific classes of compounds (such as amino acids), the effect of aqueous alteration on the full inventory of organic compounds in carbonaceous chondrites is still poorly understood.
I investigated the nature of soluble organic compounds in a full range of aqueously altered CM chondrites by electrospray ionization ultrahigh resolution orbitrap mass spectrometry. I determined that soluble organic composition was relatively consistent in CM chondrites despite varying degrees of aqueous alteration on the parent body/bodies; however, additional thermal metamorphism did show an extreme depletion in the organics identified. Additionally, I estimated the degree of aqueous alteration for CM chondrites that did not have a numerical degree of aqueous alteration via comparison of identified organics (although these estimates would need further verification). Finally, I observed that the position of the phyllosilicate-bound hydroxyl band in reflectance IR spectra of meteorites is related to the degree of aqueous alteration in meteorites. Organic-rich meteorites exhibited a maximum IR absorbance between 2.70 and 2.85 microns for the phyllosilicate-bound hydroxyl band. This research has the potential to influence asteroid sample return missions, such as the current NASA OSIRIS-REx mission, by providing a more informative and accurate correlation of sample site to organic composition.