Extra-terrestrial samples

Extra-terrestrial samples Excess xenon in meteorites 304 Extinct superheavy elements... 

Corrections can be made for any non-radiogenic argon. This is a simple procedure in terrestrial samples where there is generally some contaminating argon from the atmosphere (0.934% argon), but with a constant " Ar/ Ar ratio of 295.5 (Table 1). Such corrections are less simple in extra-terrestrial samples where the initial... 

Amino acids are distributed ubiquitously throughout much of the earth s crust, including the atmosphere (IJ. Their occurrence and important role in living organisms are well known, but amino acids have also been found in fossils and rocks hundreds of millions of years and even billions of years old (2. Amino acids have been reported at parts-per-billion levels in extra-terrestrial samples such as the Apollo moon rocks as well as in several meteorites (3,4). Even distilled water, reagent-grade HCl and other chemicals frequently contain trace amounts of amino acids. Figure 1 summarizes the levels of amino acids found in several samples of environmental Interest. 

Confidence in elemental assignment can be assured by comparison of the intensities of signals that can be ascribed to other isotopes of the element of interest, i.e. these intensity ratios should match the natural abundances isotopes listed in Appendix A.2, unless, of course, isotopic enrichment of one form or another has occurred (as is the case in nuclear reactions, extra-terrestrial samples, and so on) or has been applied (isotopic implantation). In the case of mono-isotopic elements such as Fluorine and Aluminum, molecular patterns, or even multiply charged ions, can be used to confirm assigmnents. 

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