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GC-C and GC-Pyrolysis IRMS Short Course: Putting the Gas In Gas Chromatography

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

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GC-C and GC-Pyrolysis IRMS Short Course: Putting the Gas In Gas Chromatography

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  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 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

  10. 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

  11. 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)

  12. Commercial Products 2) Isometric Instruments – Michael Whiticar - Lecture bottles of Methane mixtures in air - Isogeochem Wiki - 250, 2500, and 25000 ppm - d13C of -66.5, -54.5, -38.3, and -23.9 ‰ - dD in progress

  13. 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

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

  15. 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?

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

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

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

  19. 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!

  20. 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

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

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

  23. 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

  24. How Many Standards Do You Need?

  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? Mixture Available from Indiana University compound dD d13C C-16 -9.1 ‰ -26.15 ‰ C-17 -117.9 ‰ -31.88 ‰ C-25 -254.1 ‰ -28.48 ‰ C-29 -179.3 ‰ -31.08 ‰

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

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

  32. 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

  33. 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

  34. 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)

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

  36. 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)

  37. 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

  38. 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

  39. column sample waste Mechanical Flow Controller 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

  40. Handling Gas Samples • Canisters or bombs • Teflon baggies • Wheaton bottles

  41. Gas Tight Syringe

  42. Chromatographic Issues Baseline Separation

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

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

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

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

  47. Chromatographic Issues Air Peak

  48. Chromatographic Issues Air Peak

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