IMPROVEMENT OF THE WET-OXIDATION PROCEDURE FOR SIMULTANEOUS DETERMINATION OF PARTICULATE ORGANIC NITROGEN AND PHOSPHORUS COLLECTED ON FILTERS

A new digestion technique is presented for simultaneous analysis of pa rticulate organic nitrogen (PON) and particulate organic phosphorus (P OP) collected on filters. This method is based on a standard persulfat e digestion procedure at 120-degrees-C and adapted from a former metho d for the simultaneous determination of total nitrogen and total phosp horus in natural waters. Comparisons with usual methods using separate determinations for PON and POP indicate a high efficiency of the proc edure for cell cultures or natural seawater samples. Nitrate and phosp hate formed by oxidation can be analysed simultaneously on an automate d system. The procedure is highly suitable for routine analysis and es pecially appropriate for shipboard use.