title: Comparison of automated pre-column and post-column analysis of amino acid oligomers.
abstract: It has been shown that various amino acids will polymerize under plausible prebiotic conditions on mineral surfaces, such as clays and soluble salts, to form varying amounts of oligomers (n = 2-6).  The investigations of these surface reactions required a quantitative method for the separation and detection of these amino acid oligomers at the picomole level in the presence of nanomole levels of the parent amino acid.  In initial high-performance liquid chromatography (HPLC) studies using a classical postcolumn o-phthalaldehyde (OPA) derivatization ion-exchange HPLC procedure with fluorescence detection, problems encountered included lengthy analysis time, inadequate separation and large relative differences in sensitivity for the separated species, expressed as a variable fluorescent yield, which contributed to poor quantitation.  We have compared a simple, automated, pre-column OPA derivatization and reversed-phase HPLC method with the classical post-column OPA derivatization and ion-exchange HPLC procedure.  A comparison of UV and fluorescent detection of the amino acid oligomers is also presented.  The conclusion reached is that the pre-column OPA derivatization, reversed-phase HPLC and UV detection produces enhanced separation, improved sensitivity and faster analysis than post-column OPA derivatization, ion-exchange HPLC and fluorescence detection.
authors.affiliation: Department of Chemistry, San Francisco State University, CA 94132, USA.
authors.forename: J
authors.initials: J
authors.lastname: Chow
authors.forename: J B
authors.initials: JB
authors.lastname: Orenberg
authors.forename: K D
authors.initials: KD
authors.lastname: Nugent
mesh_terms: D000596:Amino Acids / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods* / Q000592:standards; D005069:Evaluation Studies as Topic; D005453:Fluorescence; D005998:Glycine / Q000032:analysis*; D007202:Indicators and Reagents; D008903:Minerals / Q000032:analysis; D009842:Oligopeptides / Q000737:chemistry*; D013997:Time Factors; D014466:Ultraviolet Rays; D009764:o-Phthalaldehyde
chemical_list: D000596:Amino Acids; D007202:Indicators and Reagents; D008903:Minerals; D009842:Oligopeptides; D009764:o-Phthalaldehyde; D005998:Glycine