  CR meteorites are among the most primitive meteorites. In this paper, we
report the first measurements of amino acids in Antarctic CR meteorites, two of
which show the highest amino acid concentrations ever found in a chondrite.
EET92042, GRA95229 and GRO95577 were analyzed for their amino acid content
using high performance liquid chromatography with UV fluorescence detection
(HPLC-FD) and gas chromatographymass spectrometry (GC-MS). Our data show that
EET92042 and GRA95229 are the most amino acid-rich chondrites ever analyzed,
with total amino acid concentrations ranging from 180 parts-per-million (ppm)
to 249 ppm. GRO95577, however, is depleted in amino acids. The most abundant
amino acids present in the EET92042 and GRA95229 meteorites are the alpha-amino
acids glycine, isovaline, alpha-aminoisobutyric acid (alpha-AIB), and alanine,
with delta13C values ranging from +31.6per mil to +50.5per mil. The carbon
isotope results together with racemic enantiomeric ratios determined for most
amino acids strongly indicate an extraterrestrial origin of these compounds. In
addition, the relative abundances of alpha-AIB and beta-alanine in the
Antarctic CR meteorites analyzed appear to correspond to the degree of aqueous
alteration on their respective parent body.
