An automated analysis for urea in seawater

distribution of urea in the ocean and the An automated method for the determination use of 15N-labeled urea enrichment techof urea in seawater, adapted to a Technicon AutoAnalyzer, is sensitive enough to detect niques require a method that is rapid, urea at the 0.05 pg-atom urea-N liter-l level. sensitive, and convenient for use at sea. An adaptation of the diacetyl monoxime The importance of urea as a source of reaction with urea (Newell et al. 1967) to nitrogen for marine phytoplankton has only the Technicon AutoAnalyzer meets these recently been demonstrated (Carpenter et criteria. The manual method as specified al. 1972; McCarthy 1972). The study of the by Newell et al. calls for the use of soIid NaCl, concentrated sulfuric acid, and incu’ Support was provided by Sea Grant Project bation at 70°C for 90 min. These unsuitable 061 through NOAA contract No. 2-35187. conditions were modified for the Auto-