『(Introduction)
　The determination of total phosphorus and iron in seawater has, in the past, depended either upon acid digestion or acid hydrolysis to release the organically bound fraction. Perchloric acid (P - Hansen and Robinson 1953; Fe- Lewis and Goldberg 1954) and sulfuric acid (with hydrogen peroxide) digestion (Redfield, smith, and Ketchum 1937) involve the evaporation of the sample to salts, followed by refluxing. In general, both techniques yield variable results on replicate samples, largely because of high and variable blanks. They are time consuming, difficult to use on shipboard and, in the case of perchloric acid, potentially hazardous. Both organically bound iron and phosphorus are now commonly liberated by acid hydrolysis, iron with hydrochloric acid (Armstrong 1957) and phosphorus with sulfuric acid (Harvey 1948) at high temperature (140C) over a prolonged time (5 hrs). These methods have been satisfactory, but still they are limited in their usefulness because they require an especially pressurized autoclave.
　Recently Menzel and Vaccaro (1964) showed that complete oxidation of carbon from a number of organic compounds could be obtained using potassium persulfate as an oxidizing agent. This technique has been tested to determine whether phosphorus and iron can also be satisfactorily liberated from organic combination, and it forms the basis for the method proposed here.』

Method
Recovery of total phosphorus
Recovery of iron from seawater
References