Isotope-ratio analysis using mass spectrometry is a process in which ions of a specific element are separated into a spectrum according to their mass-to-charge (m/e) ratio. Measuring the change in the 14N to 15N ratio allows researchers to follow 15N labeled material as it passes through a natural system.  Research suggests steam distillation employing EPDM rubber stoppers effect change in 14N:15N, and thus the atom percentage 15N of sample N. This study evaluates the atom percentage 15N of NH4+-N collected by steam distillation. Inorganic forms of N were reduced to NH4+-N through Devarda's alloy reduction, and acidulated in H2SO4. Ammonium samples were analyzed before and after steam distillation using an Agilent 5975C VLMSD GC/MS spectrometer, and atom percentage 15N determined. Preliminary assessment of the variability in natural abundance 15N is presented. This study provides information regarding the design of a more efficient reference procedure for use in 15N ratio analyses.

Evaluating the effect of ethylene propylene diene monomer (EPDM) rubber on <sup>15</sup>N-ratio analysis

243rd National Meeting (2012)

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Evaluating the effect of ethylene propylene diene monomer (EPDM) rubber on 15N-ratio analysis

Evaluating the effect of ethylene propylene diene monomer (EPDM) rubber on ¹⁵N-ratio analysis