nanoEA instrument method

UCSC SIL nanoEA-iRMS system
Blank correction from three standard reference materials. UCSC SIL nanoEA blanks with or without a tin capsule contain ~0.2 μg N.
Long term performance of two of three standard reference materials from data generated by UCSC SIL nanoEA for Swalethorpe et al. (2020). Red points are inter-run means of seven size-distributed replicates with 2σ error bars.

nanoEA-iRMS produces high-precision stable isotope ratio measurements of very small sample amounts (0.8–20 μg N).

The nanoEA is an automated system based on the design of Polissar et al. (2009) and is composed of a modified Carlo Erba EA1108 Elemental Analyzer connected to a Thermo Scientific Delta Plus XP isotope ratio mass spectrometer via a Thermo Scientific Gas Bench II.

The trapping system of the UCSC SiL nanoEA is supplemented with a second independent larger-volume trapping loop that facilitates independent trapping and measurement of C and N in single samples if C:N is similar to C:N of amino acids.

Measured stable isotope ratios are corrected for size effects and instrument drift with Indiana University acetanilide, USGS41 glutamic acid, and an in-house phenylalanine reference standard using correction protocols as described in Fry et al. (1992).

Long term precision of δ15N measured from 0.8–20 μg N with the nanoEA is ≤0.2‰, which is comparable or better than long term precision of identical material measured in samples an order of magnitude larger using a conventional EA-iRMS system (Swalethorpe et al., 2020).