1. Advances in Capillary Columns For Gas Chromatographic Applications
Shawn Reese, Roy Lautamo, Chris Cox
Gianna Barlupi, Rick Morehead, Jason Thomas, Gary Stidsen, and Frank Dorman

2. Old Technology?
Gas Chromatography is 50 years old! Like wine and cheese it seems to keep getting better!!
Packed columns (over 100 different phases)
Capillary debut commercially in 1970’s
Phase development parallels some packed column phases

3. Phase Development – Early Phases

4. Capillary Phase Technology
Pendant siloxanes do not show large viscosity changes with temperature (from -40 to 400oC)
High polarity applications require a wax phase which has a high temperature limit of 260
Deactivation technology varies from manufacturer and can be a limiting factor on what is possible
Pendant phases are fairly similar from manufacturer to manufacturer

5. What Does the Industry Need?
Low Bleed?
What is bleed? Can it be stopped?
“MS” Phases?
Application of low-bleed technology?
Reproducible columns?
Why do our manufacturing profiles matter to you?
Inertness
Professor Walt Jennings, Riva 2004
Selectivity-specific applications
PCB’s, Dioxins, PBDPE’s, pesticides

6. What is Bleed?
Common bleed ions associated with phases that contain PDMS
LaChatlier’s principle works against us due to the volatility of the products.

7. Slowing Down Decomposition
“G” groups spreads Si-O groups out so that they cannot “back-bite” each other and form small cyclic rings.

8. Bleed Mass Spectrum Pentamethylcyclotrisiloxane+50
100
150
200
250
300
350
400
450
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
6000
6500
7000
m/z-->
Abundance
Scan 3634 ( min): C D
207
Pentamethylcyclotrisiloxane+
Heptamethylcyclotetrasiloxane+
Trimethylsilyl+ 73
281 44 96
133
177
253
156
230
327
355
384
407
430
455
475

9. Backbone modified phases slow down the back-biting mechanism

10. Low-Bleed – 1st Generation (90’s)
What drives innovation? Introduction of “ms” phases!
As GC manufacturers make more sensitive detectors demands from the phases increase.
1st generation was a “5” in the backbone, first produced by Sveda (1951!)…did not appear in GC phases until early 1990’s.
Thermal decomposition decreased due to “stiffining” of the backbone chain.

11. Low Bleed Next Generation 21st Century
“Next” Generation was application of “other” backbone modified groups, and “new” pendant groups
Selectivity can vary dramatically if the pendant groups are very different from one another, and the backbone Group “G” is significantly different than “phenyl”.

12. What “G” groups have been used?
Literature reports the following groups:

13. Deactivations – A new problem?
Bench-top mass spectrometers in the early 90’s had sensitivity similar to the standard FID
Today, sensitivity of bench-top mass spectrometers are better than the standard FID, and the column can interfere with detection .
Inertness is a more serious issue now with detection below nanogram levels on MS.

14. What else can we do?
As the mechanism on the previous slide implies, chemically inert polymers demand the most stringent synthetic conditions
We have devised “systems” that limit the polymers ability to “find” proton sources during phase procurement through deactivation techniques and through new, proprietary syntheses.

15. Restek’s Exceptionally Inert GC Columns (Rxi)
New column technology developed by Chemists at Restek and new research lab, Restek West
Rxi-1ms, Rxi-5ms
New deactivation chemistry, new polymer chemistry, new manufacturing process
Results in columns that are:
Highly Inert
Reproducible
Low bleed

16. Reproducibility = Reliablity for the user!
In-house QC results
Comparison between manufacturers
What do you need?

17. Bleed of Manufactured Columns
Mean = 1.9pA
SD = 0.65

18. Rxi-5ms Bleed Study (30m x 0.25mm, 0.25um film)
Reference Peak
1ng tridecane
Columns include:
5% diphenyl 95% dimethyl &
Silarylene based phases
(30m x 0.25mm, 0.25um)
Detector: FID
350oC 6 4
330oC 2
Rxi-5ms

19. Retention Time “Windows” Ultimate Reproducibility Column-to-Column
Exact Length
Is this important?
Isothermal testing
Comparison of batch to batch reproducibility
In-house QC results
Film thickness
Coating efficiency
Selectivity

20. Rxi-5ms Column Reproducibility

21. Film Thickness

22. Coating Efficiency

23. Selectivity

24. Selectivity

25. Inertness
0.5ng on-column concentration
Basic compound
Acidic compound
2ng on-column comparison between manufacturers
Chromatographic peaks of pyridine
Response factor
This is the area that is a “WIP”….we have come a long way…..can it get better? We’ll show Rxi as an example of what all columns should be like!

26. Rxi-5ms Column Inertness (30m x 0.25mm, 0.25um)
Acidic Compounds
m/z 79
m/z 74
m/z 184
Basic Compounds

27. 2ng Pyridine Rxi-5ms (30m x 0.25mm, 0.25um)

28. Rxi-5ms Column Inertness (30m x 0.25mm, 0.25um)

29. Rxi-5ms Column Inertness (30m x 0.25mm, 0.25um)

30. Inertness Probes

31. Applications Environmental Clinical Semivolatile analysis
Acidic and basic drugs

32. Rxi-5ms Semivolatiles (5ng on-column)

33. Rxi-5ms Semivolatiles (5ng on-column)

34. Rxi-5ms Analysis of Drug Compounds

35. Rxi-5ms Analysis of Drug Compounds

36. Summary of Rxi Columns Unsurpassed inertness for active compounds
Low bleed
Excellent column to column manufacturing
Excellent overall performance due to combination of inertness, low bleed, and reproducible manufacturing process

37. Special Selectivity?
Application specific – not everyone is doing congener specific PCB analysis
Utilizes low-bleed technology, and incorporates many manufacturing techniques as our Rxi process
These polymers are Restek specific; cannot be found from other manufacturers

38. Rtx-440 Fused Silica Column “Special Selectivity”
Very good selectivity for chlorinated pesticides
Low bleed column
Good for GC/MS
No equivalent phases on the market

39. Rtx-440 Fused Silica Column

40. Rtx-Dioxin2
New phase that is specially “tuned” for dioxin analysis

41. Rtx-Dioxin 2

42. Rtx-PCB Congener Specific Analysis
Resolves most PCB’s into absolute separation or “MS-resolvable” separations (differing Cl numbers).
A low bleed phase – will allow for high temperature applications for “dirty” samples.

43. Rtx-PCB
place picture here

44. Rtx-5SilMs – Shape selectivity

45. Rtx-17 Fused Silica Column
Rtx-50 vs Rtx-17
Both 50% phenyl / 50% methyl
Selectivity between Rtx-50 and Rtx-17 is different
GCxGC separations coupled to a 5 or 1
Equivalent selectivity to DB-17
Rtx-50
Rtx-17

46. Acknowledgements Chris English and innovations group for applications
Roy Lautamo for suggestions on how to proceed
Shimadzu for kind invitation and providing support for this trip!!