caa a22 4500 397552939 CHVBK 20180308164755.0 cr unu---uuuuu 161202e199606 xx s 000 0 eng 10.1111/j.1574-6941.1996.tb00309.x doi (NATIONALLICENCE)oxford-10.1111/j.1574-6941.1996.tb00309.x Membrane inlet mass spectrometric analysis of N-isotope labelling for aquatic denitrification studies [Elektronische Daten] [Karen M. Jensen, Mikael H. Jensen, Raymond P. Cox] Techniques are described for measuring the isotope distribution in dissolved nitrate and N2 using membrane inlet mass spectrometry, which allows several gases to be measured in a water sample without the need for any separation steps. The isotope distribution in dissolved nitrate was measured using denitrifying Pseudomonas nautica to reduce the nitrate to N2 which was then measured by mass spectrometry. Pseudomonas nautica NCIMB 1967 was easily grown in nitrate-limited continuous culture minimising intra- or extracellular nitrate or nitrite pools, and the bioassay was tolerant of a range of salinities. The precision of the bioassay when measuring samples with high 15NO3− contents (0.5 μmol) was 0.05 atom%; with 0.1 μmol 15NO3−, the precision was around 0.2 atom%. Differences in labelling of N2 in preserved samples obtained from 15NO3− incubations of water-covered sediment cores were measured on parallel samples with membrane inlet MS and GC-MS. The membrane inlet technique was accurate but the precision on ratio measurements was lower than by GC-MS. © 1996 Federation of European Microbiological Societies. All rights reserved Isotope distribution nationallicence Nitrate nationallicence 15N nationallicence Denitrification nationallicence Bioassay nationallicence Jensen Karen M. Institute of Biochemistry, Odense University, Campusvej 55, DK-5230 Odense M, Denmark aut Jensen Mikael H. Institute of Biology, Odense University, Odense, Denmark aut Cox Raymond P. Institute of Biochemistry, Odense University, Campusvej 55, DK-5230 Odense M, Denmark aut FEMS Microbiology Ecology Blackwell Publishing Ltd 20/2(1996-06), 101-109 20:2<101 1996 20 femsec https://doi.org/10.1111/j.1574-6941.1996.tb00309.x text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1111/j.1574-6941.1996.tb00309.x text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Jensen Karen M. Institute of Biochemistry, Odense University, Campusvej 55, DK-5230 Odense M, Denmark aut NATIONALLICENCE 700 1- Jensen Mikael H. Institute of Biology, Odense University, Odense, Denmark aut NATIONALLICENCE 700 1- Cox Raymond P. Institute of Biochemistry, Odense University, Campusvej 55, DK-5230 Odense M, Denmark aut NATIONALLICENCE 773 0- FEMS Microbiology Ecology Blackwell Publishing Ltd 20/2(1996-06), 101-109 20:2<101 1996 20 femsec Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford