Simultaneous determination of particulate organic carbon, nitrogen and phosphorus collected on filters, using a semi- automatic wet-oxidation method

A wet-oxidation method is presented for determining simultaneously particulate organic carbon (POC), particulate organic nitrogen (PON) and particulate organic phosphorus (POP) collected on filters. Conversion of POC, PON and POP to inorganic products, carbon dioxide, nitrate+nitrite and soluble reactive phosphate respectively, is performed by a persulfate wet-oxidation in slight alkaline condition. After oxidation, inorganic products are dissol\ted In t l l ~ ! digestion mixture and concentrations are measured dutomaticdlly by colorimetry using a 3 channel Techn~con ~ u t o ~ n a l y 7 ~ r " ' . Concurrent comparisons .were made with dry combustion at 950°C for POC and PON (CI4N analysis) and with former wetoxidation procedure for POP. Results indicated high efficiency to oxidize natural suspended particulate matter from seaand freshwater as well as phytoplankton cultures and sinking particles collected by sediment traps. This method also exhibits good reliability and precision in comparison with former procedures and is highly suitable for routine analysis and especially appropnate for shipboard work.