Fluorometric Determination of Amino Acids Dissolved in Sea Water

Abstract

   A new method of fluorometric microdetermination of free and total amino acids in sea water is presented by using o-phthalaldehyde (OPTA)-amino acids fluorogenic adduct adsorbed on XAD-2 resin. Free amino acids react to OPTA without any treatment prior to the analysis, and the total amino acids react to the reagent after the acid hydrolysis. Subsequently the reaction adduct was separated from the solution by the adsorption on XAD-2 resin. The fluorogenic product was eluted from the resin with methyl alcohol followed by fluorometric determination of λ_ex=360 nm and λ_fl=455 nm. The recovery by this method is 93.3% for free amino acids and 90.4% for total amino acids with a standard deviation of less than 2%. The method has advantages over the ninhydrin and fluorescamine method because of high sensitivity and room-temperature reaction.