Quantitative determination of particulate organic N and C in marine-phytoplankton samples using mass-spectrometer signals from isotope-ratio analyses in 15N- and 13C-tracer studies

Abstract A gas-sampling device between an oven for Dumas combustion and an isotope mass spectrometer enables the determination of particulate organic N and C concentrations during isotopic 15 N and 13 C analysis of phytoplankton samples from dual-labelling experiments. A description of the interface is given with details of the operating procedure. The precision of the method was comparable with an elemental C-N analyser with a C.V. of 2.70% at the level of 5.17 μmol for N and 7.26% at the level of 48.77 μmol for C.