6
Using EA IsoLink IRMS System for CNSOH
High-Temperature Conversion – Analysis of H and O Isotopes
94
EA IsoLink IRMS System for CNSOH Operating Manual
Thermo Scientific
High-Temperature Conversion – Analysis of H and O Isotopes
The separation column is installed in the GC Oven of the EA together with the TCD. During analysis
the temperature should be kept in a range between 70 - 90 °C. Nitrogen containing samples may be
run at low temperature using dilution at the elution of the N
2
prior to the CO
To achieve longer maintenance periods, the pyrolysis side has a trap filled with
Carbosorb®
(e.g.
Ascarite®
P/N 338 35236) and
Magnesium Perchlorate
(P/N 338 21900). These chemicals remove
CO
2
and water from the carrier gas at standby temperatures of the reactor minimizing the bake-out
intervals. The filling of the trap is given in
using quartz wool at top and end, and to
separate the filling material.
Figure 102.
Trap Pyrolysis
Bottom Field Connector
The EA IsoLink IRMS System for CNSOH is equipped with a bottom feed connector for high
temperature conversion analysis, also referred to as pyrolysis. It allows high sample throughput.
This connector supplies the carrier gas helium from the bottom into the reactor. The helium flows up
and is redirected downwards through the glassy carbon tube where it exits at the bottom connector
again. See
.
Figure 103.
Flow Path with Conventional and Bottom Feed Connector
Note
Bake-out at maximum temperature for at least 24 hours (plus carrier flow for both analytical
sides) must be considered when separation of the peaks is not sufficient any more or if
δ
18
O
precision, accuracy, or both are deteriorating.
