GCMS - Gas Chromatograph Mass Spectrometer. In this instrument, gas is moved through a column containing an absorbant phase and then through a mass spectrometer to determine the concentration of various compounds.
NMR spectrum - A spectrum produced by nuclear absorption at characteristic radio wavelengths by the application of a magnetic field. Used for the study of macromolecular carbon in carbonaceous chondrites.
isomer - one of two or more chemical substances having the same elemental composition but different structures. Examples are n-butane, CH3(CH2)2CH3, and isobutane, CH3CH(CH3)2.
carboxylic acid - An organic acid characterized by one or more COOH groups. A carboxylate contains such groups.
fatty acid - An organic acid with the general formula CnH2n+1COOH.
aliphatic hydrocarbon - An organic compound characterized by straight chains of carbon atoms. Alkanes, alkenes, and alkynes are types of aliphatic molecules.
aromatic hydrocarbon - A class of organic compound containing at least one benzene ring (C6H6). Multiply-ringed compounds of this type are known as polycyclic aromatic hydrocarbons, abbreviated as PAHs. PAHs are ubiquitous, and are found, for example, in burned toast and the interstellar medium. They have also been identified in some martian meteorites but are apparently absent (as are all other organic molecules) in surface dust on Mars.
amino acid - An organic compound that contains one or more basic amino (NH) groups and one or more carboxyl (COOH) groups. Roughly 80 amino acids are found in nature, but only 20 are used by life to construct proteins.
homologues - This refers to a series of molecules that have a fundamental building block on which additional groups are placed. Examples include compounds with various chain lengths.
enantiomer - this a compound which is a "mirror image" of another compound, in that the two compounds have the same composition but two configurations that can be superimposed by the action of a mirror-like reflection (as in our left and right hands). The ability of some molecules to be represented by left & right-handed symmetry is also known as chirality. Examples of enantiomers or chiral compounds include "right-handed" (D) and "left-handed" (L) amino acids. Life uses only L-amino acids. An approximately equal mixture of L- and R-handed molecules is known as a racemic mixture.
del D - this is the ratio of heavy hydrogen (deuterium, or D) to normal hydrogen expressed in parts per thousand relative to a standard; the del notation is the same as for oxygen-isotope ratios as in the following example for del18O:
del 13C - this is the ratio of 13C to 12C expressed in parts per thousand relative to a standard; the del notation is the same as for oxygen-isotope ratios.
del15N - this is the ratio 15N to 14N expressed in parts per thousand relative to a standard; the del notation is the same as for oxygen isotope ratios.
supercritical CO2 - this is carbon dioxide that has properties intermediate between a liquid and a gas, present at high temperatures.
purine - a heterocyclic compound containing pyrimidine (C4H4N2) and imidazole (C3H4N2) rings.
alkyl - the CnH2n+1 radical.
Fischer-Tropsch (FTT) synthesis - a process that can create complex hydrocarbons by combining CO, H2 and other gases in the presence of grain surfaces that provide a catalytic reaction, which speeds up chemical reaction.
Miller-Urey synthesis - a process that can create
complex hydrocarbons from a hydrogen-rich (e.g., CH4, NH3)
gas mixture in the presence of water, following application of energy (such
as a spark).
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An example of a Miller-Urey synthesis, involving the creation of
tarry orange compounds (tholins, including amino acids) after
electrical discharges in a flask filled with a methane +
ammonia gas mixture over water.
Strecker synthesis - production of carboxylic acids & amino acids from aldehydes, involving N addition with a complex pathway
alcohol - a class of organic compound containing hydroxyl (OH) groups.
aldehyde - a class of organic compound containing the CHO radical.
carbonyl - a compound that contains a CO group.
ketone - A class of organic compound containing C, O, and at least two additional molecular groups. Ketones are important intermediates in the synthesis of organic compounds.
moiety - a complex part or portion of a molecule.
stepped combustion analysis - This is an analysis
procedure that measures the gases evolved from a sample during stepwise
progressive heating.