Table 1. Diamino acid identification in the Murchison meteorite.

Diamino acid	Mass trace, amu	Retention time, min	Quantity, ppb
(2,5-Diaminopyrrole)	168, 96	26.10	39.5 ± 3.7
4,4′-Diaminoisopentanoic acid	142, 116	27.79	32.2 ± 3.3
d-2,3-diaminopropanoic acid	175, 129, 102	28.92	49.9 ± 4.2
l-2,3-diaminopropanoic acid	175, 129, 102	29.69	49.8 ± 4.2
d-2,4-diaminobutanoic acid	175, 116	32.47	31.6 ± 3.3
3,3′-Diaminoisobutanoic acid	188, 142, 115	32.58	48.6 ± 4.1
l-2,4-diaminobutanoic acid	175, 116	33.06	29.9 ± 3.2
d-ornithine	142, 129	43.26	<5
l-ornithine	142, 129	44.54	<5
2,3-Diaminobutanoic acid*	203, 157, 85	38.62	89.9 ± 6.2
(A-unidentified)*†	216	20.19	7.1 ± 2.0
(B-unidentified)*†	216	20.39	7.2 ± 2.0

Numbers shown in boldface are the main mass fragments. ppb, parts per billion, i.e., ng analyte per g Murchison. The diamino acid quantities were calculated by comparison of the peak areas with external diamino acid standards. The uncertainties were calculated from a calibration of the analytical procedure.

^*Gas chromatograms taken in deviation from the standard protocol on 12-m Chirasil-l-Val stationary phase, with oven temperature programmed for 3 min at 70°C, 5°C·min^-1, and 17.5 min at 180°C

^†A, the first eluting enantiomer; B, the second eluting enantiomer of a hitherto unidentified structure, most likely a diamino acid