THE STUDY OF THE DISSOLVED NITROGEN CONTAINING MACROMOLECULES IN THE MARINE ENVIRONMENT

Abstract

A method was developed for the direct determination of the dissolved combined amino acid (DCAA) content of seawater involving the acid hydrolysis of seawater under specified conditions, followed by the determination of the amino acids by reverse phase liquid chromatography (RPLC). No preconcentration or co-precipitation steps were required. Under optimal conditions approximately sixty percent of the total amino acids in the macromolecular fraction are probably recoverable by this procedure. The commonly used reflux method for DCAA detection was shown to be inaccurate due to a combination of degradative losses and contamination. The technique of DCAA determination, developed in this study, was not suitable for estuarine or other waters containing high nitrate levels, due to the occurrence of oxidative losses. The seasonal relationship between the dissolved combined and the dissolved free amino acid levels and compositions , both at surface and at depth in the coastal waters of Plymouth UK, were studied .