Eschenbach, W. und Dyckmans, J. und Giesemann, A. und Well, R. und Stange, F.
(2017)
SPIN-MIMS simplifying the SPIN-MAS instrumentation for online measurement of 15N-abundances of ammonium, nitrite and nitrate in aqueous solutions.
In: Jahrestagung der DBG 2017: Horizonte des Bodens, 02.-07.09.2017, Göttingen.
Kurzfassung
Common methods for measuring selectively the 15N abundances in individual N-species such as NH4+, NO2- and NO3- in samples with multiple N-species are laborious and time consuming.
The SPIN-MAS technique (Stange et al. 2007) offers an automated, rapid and selective determination of 15N abundances in NH4+, NO2- and NO3- in aqueous samples. During a SPIN-MAS measurement one of three different reaction solutions is mixed with the aqueous sample in a Sample Preparation unit for Inorganic N-species (SPIN). The reaction solution is chosen in dependence on the N-species of interest. The gaseous reaction products (N2 or NO) are then conducted to a quadrupole mass spectrometer (MAS) in a helium stream. This measurement technique is not commonly used due to its complex instrumentation.
The instrumentation can be significantly simplified by the use of a membrane inlet mass spectrometer (MIMS). The presented SPIN-MIMS approach relies on the use of a reaction capillary in which the sample containing the N-species of interest is mixed with the corresponding reaction solution. The mixture of reaction solution and sample is pumped from the reaction capillary directly to the membrane inlet of the mass spectrometer. The reaction products (N2 or NO) formed during the reaction of NH4+, NO2- and NO3- with the reaction solutions are passed through the gas-permeable membrane of the inlet directly into the ion source of the mass spectrometer.
15N standards with different at% 15N (NH4+, NO2- and NO3- respectively in dist. Water) were used to assess the performance of the system. Overall, SPIN-MIMS measurements showed a good agreement between measured and expected 15N abundances (range 0.36 – 10 at% 15N deviations: <0.5 at% 15N for NH4+-, <0.23 for NO2-- and <0.15 at% 15N for NO3-- standards).
Aktionen (Anmeldung erforderlich)
 |
Eintrag anzeigen |
