Carbon
and nitrogen isotope values of BAM were measured on a GC-IRMS system.
A DB-5 analytical column (60 m, 0.25 mm i.d., 0.5 μm film, Agilent
Technologies, Germany) was used in a TRACE GC Ultra gas chromatograph
(Thermo Fisher Scientific, Italy) which was coupled to a Finnigan
MAT 253 isotope-ratio mass spectrometer through a Finnigan GC Combustion
III interface (Thermo Fisher Scientific, Germany). The typical total
uncertainty of carbon isotope measurements is ±0.5‰, and
the uncertainty of nitrogen isotope measurements is ±1‰.
The method, including solid-phase extraction before CSIA, is described
by Sun et al.54 (link) and provided in theSupporting Information .
and nitrogen isotope values of BAM were measured on a GC-IRMS system.
A DB-5 analytical column (60 m, 0.25 mm i.d., 0.5 μm film, Agilent
Technologies, Germany) was used in a TRACE GC Ultra gas chromatograph
(Thermo Fisher Scientific, Italy) which was coupled to a Finnigan
MAT 253 isotope-ratio mass spectrometer through a Finnigan GC Combustion
III interface (Thermo Fisher Scientific, Germany). The typical total
uncertainty of carbon isotope measurements is ±0.5‰, and
the uncertainty of nitrogen isotope measurements is ±1‰.
The method, including solid-phase extraction before CSIA, is described
by Sun et al.54 (link) and provided in the
