Liquid chromatography techniques using fluorescent derivatives and laser-induced fluorescence can separate and detect sub-femtomole levels of amino acids. The widespread distribution of amino acids and proteins from living organisms produces nanomolar and higher levels of amino acid material in most environments of the earth's surface. Contamination usually occurs to some extent during sample collecting and processing and must be recognized and addressed before meaningful amino acid concentrations and distributions can be obtained from environmental samples.
Amino acids are distributed ubiquitously throughout much of the earth's crust, including the atmosphereTheir 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 HC1 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.Current analytical techniques for the analysis of the common amino acids are able to detect less than femtomole (10~15) amounts using liquid chromatographic methods with fluorescent derivatives. However, this level of sensitivity may be extremely difficult to utilize because of the widespread presence of amino acids from living organisms. For example, the relatively high levels of amino acids in human body tissues and fluids make human fingerprints or even a person's breath a potential serious contaminant in detecting amino acids in specific environmental samples (5). Sample collecting and preparation are major concerns to amino acid trace analysis. Even with careful handling during sample collection and preparation it is always possible that the sample may have been contaminated in situ before its collection.