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The Design of High Temperature CapillaryGas Chromatography Columns Based on

Polydimethylsiloxane

Jarl Snider, D. J. Hotnisky, Kristi Sellers,Jarl Snider, D. J. Hotnisky, Kristi Sellers,Dinesh V. PatwardhanDinesh V. Patwardhan Ph. D.Ph. D.

Outline

BackgroundBackground

Definition of TerminologyDefinition of Terminology

Unique Attributes of High Temperature ColumnUnique Attributes of High Temperature Column

ApplicationsApplications

ConclusionsConclusions

Polydimethylsiloxane

Si O

CH3

CH3

nHHO

Sin

CH3

CH3

OSi

CH3

CH3

CH3CH3

H3C

CH3

Si O

Thermal Stability of PDMS

Adapted from Siloxane Polymers, ed. Clarson & Semlyen, 1993.

Beginning ofdecomposition

Bleed

•• Chromatography of “loose” silicones from theChromatography of “loose” silicones from thecolumncolumn

temperature

pA

Bleed

Typical Chemical Structure of Bleed

S i

O O

S i S i

O

M e

M e

M e

M e

M e

M e

D 3

Me Me

Me

Me

Me Me

Me

Me

OSiO

O

Si

SiO

Si

D4

Challenge

•• Since the decomposition temperature for PDMS isSince the decomposition temperature for PDMS is343°C, it is a challenge to make a column that is343°C, it is a challenge to make a column that isstable and has low bleed at 380°C.stable and has low bleed at 380°C.

Origin of Bleed

•• Polymer SynthesisPolymer Synthesis

•• Oligomers that are “created” in a column’s lifetimeOligomers that are “created” in a column’s lifetime

Origin of Bleed...

•• Polymer SynthesisPolymer Synthesis

Adapted from Inorganic Polymers, Mark, Allcock, & West 1992.

Polymer Synthesis

•• Silicone Polymers can be synthesized using wellSilicone Polymers can be synthesized using wellknown catalysts (KOH, HCl) under equilibrationknown catalysts (KOH, HCl) under equilibrationpolymerization conditions.polymerization conditions.

•• We use newer, more advanced catalysts, betterWe use newer, more advanced catalysts, bettersynthetic techniques.synthetic techniques.

Origin of Bleed...

•• Polymer SynthesisPolymer Synthesis

•• Oligomers that are “created” in a column’s lifetimeOligomers that are “created” in a column’s lifetime

Origin of Bleed...

•• Oligomers that are “created” in a column’s lifetimeOligomers that are “created” in a column’s lifetime

OSi Si

OSi

OSi

OSi Si

OH

SiO

Si

OH

(polymer coating)

PDMS

D3/D4 bleed

(FS tubing)

[ ]

Enhancement of Thermal Stability by Using“Additives”

Si O

CH3

CH3

OSi O

CH3

CH3

CH3

CH3

SiSix y z

SilphenyleneSilphenylene

Additives...

•• A column with true “One” selectivity cannot beA column with true “One” selectivity cannot beobtained by having silphenylene in the backbone.obtained by having silphenylene in the backbone.

Si O

CH3

CH3

nSi Si

CH3

CH3

CH3

CH3

Om

StxTM-1 HT

•• The polymer or the phase is PDMS.The polymer or the phase is PDMS.

n

C H 3

C H 3

OS i

Origin of Bleed...

fused silica

deactivation

Origin of Bleed...

fused silica

deactivation

Deactivation of the Fused Silica Surface

•• We are using an advanced deactivation calledWe are using an advanced deactivation calledSiltek™. It is a deposition process, unlike silazaneSiltek™. It is a deposition process, unlike silazaneor silicone deactivation.or silicone deactivation.

Aroclor® 1242

8 16 24

Aroclor® 1254

8 16 24

Aroclor® 1260

8 16 24

Aroclor® Run Conditions

Splitless Hold Time: 1.0min.Split Vent Flow: 40cc/min.Septa Purge: 5cc/min.Carrier Gas: HeliumHead Pressure: 8.5psiColumn Flow Rate: 1.9cc/min.Linear Velocity: 31cm/sec.Detector: ECD/310CMake up Gas Flow: 40cc/min.

Temp. Program: 75°C(1.0min.) 15°C/min.to 150°C(0) 5°C/min.300°C(10min.)

Column: Stx-HT1Serial #: 215041Description: 30m, 0.32mmID, 0.10µmSample: Aroclor Solutions

Part #32009, 32011, 32012

Concentration: 400ppb

Solvent: HexaneSample Size: 1.0µL

Instrument: HP5890Injector: Splitless/275°C

PCB Congeners

4 8 1612

1

2

3

45

6 7

Column: Stx-HT1Serial #: 215041Description: 30m, 0.32mmID, 0.10µm

Sample: PCB Congener Standard #2Part #32294

Concentration: 100ngSolvent: Iso-OctaneSample Size: 1.0µL

Instrument: HP5890Injector: Splitless/275°CSplitless Hold Time: 0.80min.Split Vent Flow: 40cc/min.Septa Purge: 5cc/min.Carrier Gas: HeliumHead Pressure: 8.5psiColumn Flow Rate: 1.9cc/min.Linear Velocity: 31cm/sec.Detector: ECD/310°CMake up Gas Flow: 40cc/min.

Temp. Program: 100°C(0.80min.) 15°C/min.to 325°C(10min.)

Elution Order:1. BZ#282. BZ#523. BZ#1014. BZ#1185. BZ#1536. BZ#1387. BZ#180

*PCBs numberedaccording toBallschmiter

10ppm Aliphatics

1

2420 28

2

3

4

5

16

30m, 3.32mmID, 0.01µm Stx™-1HT (cat.# 11709)Solvent: HexaneOven temp.: 30°C (hold 0.5 min.) to 240°C at

15°C/min. to 380°C at 10°C/min.(hold 10 min.)

Det.: FID at 340°CInj.: splitless at 250°CCarrier: hydrogenFlow rate: 4.0cc/min. at 30°CMake-up gas flow: 40cc/min.

1. C242. C263. C284. C305. C36

Bleed Comparison

Rtx®-1MS

Stx™-1HT

340°C 360°C 380°C

4.34pA

6.94pA

6.07pA

15.61pA11.27pA

39.02pA

50ppm Hydrocarbons

4 128 16

1

Aliphatic hydrocarbons:

1. C92. C103. C124. C145. C16

2 1

3

2

3 4

4

55

67

67

8

8

9

9

1011

10

11

12

13

14

12

13

15

16

17

6. C187. C198. C209. C2210. C2411. C2612. C2813. C30

Aromatic Hydrocarbons:

1. napthalene2. 2-methylnaphthalene3. acenaphthylene4. acenaphthene5. fluorene6. phenanthrene7. anthracene8. fluoranthene9. pyrene10. benzo(a)anthracene11. chrysene12. benzo(b)fluoranthene13. benzo(k)fluoranthene14. benzo(a)pyrene15. indeno(1,2,3-cd)pyrene16. dibenzo(a.h)anthracene17. benzo(g,h)perylene

Analysis Conditions

30m, 3.32mmID, 0.01µm Stx™-1HT (cat.# 11709)Oven temp.: 30°C (hold 0.5 min.) to 240°C at

15°C/min. to 380°C at 10°C/min.(hold 10 min.)

Det.: FID at 340°CInj.: splitless at 250°CCarrier: hydrogenFlow rate: 4.0cc/min. at 30°CMake-up gas flow: 40cc/min.

1.0µL injections of MA EPH Aliphatic Hydrocarbonstandard (cat.# 31459, solvent: hexane) & MA EPHAromatic Hydrocarbon standard (cat.# 31458, solvent:methylene chloride) @ 50ppm concentration.

ASTM D2887

2

1

3

4

5

6

7

8

9

10 11

12 13 14 15 1617 18

19 20 2122 23

30m, 3.32mmID, 0.01µm Stx™-1HT (cat.# 11709)Oven temp.: 30°C to 380°C at 10°C/min.Det.: FID at 380°CInj.: cool on-columnCarrier: heliumFlow rate: 1.3cc/min. at 30°CLinear velocity: 22cm/sec. at 30°CMake-up gas flow: 45cc/min.Head pressure: 6.0psi

1. C72. C83. C94. C105. C116. C127. C148. C169. C1810. C2011. C2412. C28

13. C3214. C3615. C4016. C4417. C4618. C4819. C5020. C5221. C5422. C5623. C58

XTI Mix on Rtx-1 & Stx-1HT

Rtx®-1

Stx™-1HT

1

14

2

3

4

5

67

8

9

10 11 12

13

1

14

2

34

5

6

7 8

9

10 11 12

13 1. 1,2-hexanediol2. nitro-di-N-propylamine3. benzoic acid4. C145. 2,4-dinitrophenol6. nitrophenol7. nitroaniline8. pentachlorophenol9. carbazole10. C2011. C2112. C2213. benzo(b)fluoranthene14. benzo(k)fluoranthene

Summary

•• DefinitionsDefinitions

•• The design of low bleed & stable column systemThe design of low bleed & stable column systemwas discussedwas discussed

•• Several applications were shownSeveral applications were shown