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University of Southern California
USC Dana and David Dornsife College of Letters, Arts and Sciences  
Sarah Feakins, PhD | USC College of Letters, Arts, & Sciences
 

IRMS RESOURCES

Running and optimizing a continuous flow mass spectrometer is not a simple feat. Many hours of method development, troubleshooting and optimization go into a successful operation. Here are a few tips and tricks that we have developed along the way.

ISL Scripts

slow ramp to heat HTC reactor

slow ramp to cool HTC reactor

slow ramp to heat Comb reactor

slow ramp to cool Comb reactor

Explanation:

The GC Isolink from Thermo has a computer controlled furnace to heat the pyrolysis and combustion reactors. Here we provide an isl script that can be opened and run in workspace that will heat/cool the HTC reactor at a slow rate. The goal is to minimize the development of leaks at solder points, leaks at fittings and microcracks in the reactor. The rate, and set-point temperature can be modified in the script. The script could be modified for the combustion reactor.

Details on how to save and run scripts in Isodat:

*Please note that you use and implement the scripts and these instructions at your own risk.*

  1. Save the files in the same directory along with Thermo ISL scripts C:\Thermo\Isodat NT\Global\ISL\GC Isolink.
  2. Open the ISL script in workspace set the temperature in the script to the target temperature (endT) and then click '! Run' tab.
  3. Leave the script open in workspace. Switch over to Instrument control and you can see the temperature ramp happening (slowly) in the GC Isolink window.

Analytical setup in the Feakins lab:

GC-IRMS – Gas Chromatography Isotope Ratio Mass Spectrometry

We use a Thermo Scientific Trace GC equipped with a Rxi®-5ms (30m x 0.25mm, film thickness 1mm); and a TriPlus programmable injector connected via GC Isolink with parallel combustion furnace (at 1030 °C) and pyrolysis furnace (at 1430 °C) together with a Conflo IV to a Delta V Plus mass spectrometer. Combustion is used for the analysis of 13C/12C and pyrolysis is used for the analysis of D/H.

EA-IRMS – Elemental Analyzer & Isotope Ratio Mass Spectrometry

We use a Costech EA in standalone mode or coupled via a Conflo IV to a Delta V Plus mass spectrometer for TC, TOC, TIC, TN, C/N, d13C TC, d13C TOC, d13C TIC, d15N TC.