1. GC-C and GC-Pyrolysis IRMS Short Course: Putting the Gas In Gas Chromatography
Paul Eby

2. GC-C and GC-Pyrolysis IRMS Short Course: Putting the Gas In Gas Chromatography
Part 1: Standards
Part 2: GC Set Up
Part 3: Combustion & Pyrolysis

3. Part 1: Standards

4. - Thermo Fisher product literature
Thermo GC IsoLink
- Thermo Fisher product literature
Potential Sources of Error:
Sample handling - Injection - Interferences
Column effects - Reactors - Poor separation
Leaks - Open split - Integration

5. How to Introduce a Standard
A separate run of the same compound
Spike all samples with a reference material that does not interfere
AVOID USING A REFERENCE GAS PULSE AS YOUR STANDARD!!!!!!!

6. Identical Treatment
The reference and sample should be measured in the same way
The reference and sample should be the same compound (or class of compound)
3) The reference and sample should be as similar in composition and concentration as possible

7. GSQ PLOT column
60m, 0.32mm ID, 30C

8. dD on CH4 and H2
60m GSQ PLOT column

9. Where Do You Find Reference Materials?
NIST / IAEA
Commercial Products
Make it yourself
Beg/borrow/steal

11. A New Natural Gas Standard?
Something to replace SRM8559, 8560, 8561
An effort is underway, headed by Dr. Ellis at USGS
Probably won’t be ready until 2015

12. Commercial Products Oztech – Chuck Douthitt
- Lecture bottles of pure Hydrogen, Carbon Dioxide and Nitrogen
- Isogeochem Wiki
CO2 (d13CPBD, d18OPDB) (-3.6, -16), (-10.5, -10), (-40.7, -30), (-44.5, -31), (-47.6, -37)
H2 (dDSMOW) (+100), (0), (-60), (-120), (-160), (-225), (-400), (-800)
N2 (d15NAIR) (0)

13. Commercial Products 2) Isometric Instruments – Michael Whiticar
- Lecture bottles of Methane mixtures in air
- Isogeochem Wiki
- 250, 2500, and ppm
- d13C of -66.5, -54.5, -38.3, and ‰
- dD in progress

14. Commercial Products 3) Indiana University – Arndt Schimmelmann
Isogeochem wiki
Pure compounds and mixtures
dD, d13C, d15N, and d18O
GC and EA
- n-Alkanes (C1 to C50)
Fatty acid esters
Aromatics
Nitrogen containing organics

15. Make It Yourself
Find a way to compare your material to one of these:

16. Make It Yourself Dual Inlet / Off-line Methods
Pure CO2 vs Pure CO2 (SRM 8562, 8563, 8564)
Problem with CO2 tanks containing liquid
Pure Hydrocarbons vs Pure CO2
Hydrogen?

17. Make It Yourself 2) Elemental Analyzer Methods
Plenty of EA standards available from NIST/IAEA for 13C

18. Make It Yourself 2) Elemental Analyzer Methods
Even liquids and gases!!!!!
Oztech standards

19. Make It Yourself
2) Elemental Analyzer Methods
How about Hydrogen?

20. Make It Yourself 2) Elemental Analyzer Methods How about Hydrogen?
HDevice:
- SMOW, GISP, SLAP
- Oztech H2 standards
- Methane, ethane, propane, butane
- Liquid hydrocarbons?
- Check the temperature!

21. Make It Yourself 2) Elemental Analyzer Methods How about Hydrogen?
TC/EA:
- SMOW, GISP, SLAP
- Oztech H2 standards
- Methane, ethane, propane, butane
- Liquid hydrocarbons?
- Solids autosampler

22. Make It Yourself 2) Elemental Analyzer Methods How about Hydrogen?
Other Instruments:
- Elementar Vario PYRO Cube
- Thermo FLASH HT

23. Beg/Borrow/Steal…. How much trust do you give these standards?
How were they created?
Are they traceable to NIST/IAEA standards?

24. How Many Standards Do You Need?
One is okay, two is good, three is better
Range should bracket that of your samples
A single standard is better than two close together

25. How Many Standards Do You Need?

26. How Many Standards Do You Need?

27. How Many Standards Do You Need?

28. How Many Standards Do You Need?

29. How Many Standards Do You Need?

30. How Many Standards Do You Need?
Mixture Available from Indiana University
compound dD
d13C
C-16
-9.1 ‰ ‰
C-17 ‰ ‰
C-25 ‰ ‰
C-29 ‰ ‰

31. How do you inject samples?
Part 2: GC Set Up
How do you inject samples?
Gases Liquids
6-Port Valve
Split/Splitless
Injector

33. Points to Remember: - Septum damage - Different types of liners
- Cleaning the liner
- Capillary insertion
- Ferrule can leak
- Temperature

34. 6 Port Valve for Injection of Gas
Produced by Valco
Rheodyne?
Exchangeable sample loops 5 uL to 1 mL
2 positions: load and inject
1/8” vs 1/16” ports
Rotor replacement

35. 6 Port Valve for Injection of Gas
column He
sample
waste
Max loop size: 1.0mL  20ppm CH4
Max loop size without focusing: 100uL  200ppm
Min loop size: 5uL  5% CH4

36. Internal Volume Valve for Injection of Gas
column He
sample
waste
Sample volume is the path etched on the rotor
0.06 uL to 2 uL  100% CH4 (0.5uL)

37. Regulating Column Flow
sample
column
waste He
Electronic Flow Controller?
Mechanical Pressure Regulator?
Mechanical Flow Controller?

38. Electronic Flow Controller
Most new GC’s have them
Great for split/splitless injectors
Difficult for 6-port valves
Be mindful of the two types:
Mass flow controller
Electronic pressure controller (calculates flow)

39. Mechanical Pressure Regulator
Common on older GC’s
Set the head pressure on the column
Flow varies depending on the column temp
Operates by adjusting the tension on a diaphragm

40. Mechanical Flow Controller
Common on older GC’s
Maintain a constant flow
Vary the head pressure as column temp changes
Needle valve
Combo Valve from Valco

41. Mechanical Flow Controller
sample
column
waste He
Pressure gauge shows column head pressure
Rises as you go through Temp ramp (constant flow)
Pressure drops to zero for a leak
Pressure increases to inlet pressure for a plug

42. Handling Gas Samples
Canisters or bombs
Teflon baggies
Wheaton bottles

43. Gas Tight Syringe

44. Chromatographic Issues
Baseline Separation

45. Chromatographic Issues
Baseline Separation
Separation is generally worse than normal GC-MS
Broadening in the source

46. Chromatographic Issues
When is it a Good Peak?
Separate runs of pure compounds
Sensitivity analysis of integration

47. Chromatographic Issues
When is it a Good Peak?
45/44 is NOT homogenous through the peak
Tails are important for the integration

48. Chromatographic Issues
Air Peak
Integrates at +500 permil
Why does air show up on 44/45/46?

49. Chromatographic Issues
Air Peak

50. Chromatographic Issues
Air Peak

51. Chromatographic Issues
Air Peak
Masses 48, 49, 50

52. Part 3: Combustion and Pyrolysis
Converting your peaks to H2 and CO2

53. Combustion A good resource:
Performance and Optimization of a Combustion Interface for Isotope Ratio Monitoring Gas Chromatography/Mass Spectrometry
Dawn A. Merritt, Katherine H. Freeman, Margaret P. Ricci, Stephen A. Studley, J. M. Hayes
Anal. Chem., 1995, 67(14), pp 2461–2473

54. Combustion Ceramic Tube 0.5 mm ID Alumina (inert, gas impermeable)
Metal wires
mm diameter
- Copper or nickel
- Platinum
3) Oxygen

55. Combustion Input capillary should be inserted 1cm
Capillary Tubing from GC
ZV Fitting
ZV Fitting
Alumina Tube
Wire
Input capillary should be inserted 1cm
Wires need to be centered in the hot zone
Approx 15cm in a 30cm tube

57. What Metal? Copper/Platinum Trouble with methane - 3 Cu and 1 Pt wire
Nickel/Platinum
- 3 Ni and 1 Pt wire °C
3) Copper/Nickel/Platinum °C
Trouble with methane
Holds on to oxygen longer
Longer life
Higher Temperature
Hybrid

58. Thermo Oxidation Reactor

59. Oxidation Periodic Reoxidation Can run out of O2 - 100% O2 - Backflush
2) Oxygen Bleed
- Trickle in 1% O2 in He
- Always On
Can run out of O2
Can’t use for a while
Constantly regenerating
Never run out
Difficult to balance

61. Pyrolysis: Shouldn’t this be easy? Just an empty ceramic tube
Conditioning required
1450°C

62. Pyrolysis: Shouldn’t this be easy?
Conditioning is necessary to deactivate the interior surface
Large quantity of a hydrocarbon will deposit carbon
If you do too much you can block the tube:

63. Pyrolysis: Shouldn’t this be easy? If you don’t do enough:
Alumina is actually a poor choice of materials
Water of combustion

64. Pyrolysis: Water Trouble No Nafion trap required
Water contamination injected with the sample: