Column Selection. there is more to life than a boiling point column. Jaap de Zeeuw Restek Corporation, The Netherlands. Copyrights: Restek Corporation

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1 Column Selection there is more to life than a boiling point column Jaap de Zeeuw Restek Corporation, The Netherlands

2 Stationary Phase Selectivity Boiling Point versus Solubility Retention of a compound can be related to boiling point or solubility The solubility of a compound in the stationary phase is a better predictor of retention than boiling point.. So.. what do we mean with boiling point separation columns and where are they used as such?

3 Rtx-1 100% polydimethyl siloxane Alkanes 2,3 Run Conditions: Dimensions: Temperature: Carrier Gas: Flow: Head Pressure : Injection: Detector: Rtx-1 30m, 0.32mm ID, 1.0 μm 70 o C Isothermal Helium at 20 cm/sec ml/min 5.91 psig Split FID 1. acetone 56 o C bp 2. pentane 36 o C 3. propanol 97 o C 4. MEK 80 o C 5. hexane 69 o C 6. butanol 118 o C 7. 3-pentanone 101 o C 8. heptane 98 o C 9. pentanol 138 o C 10. octane 126 o C

4 Rtx-1 100% polydimethyl siloxane Ethers 2,3 Run Conditions: Dimensions: Temperature: Carrier Gas: Flow: Head Pressure : Injection: Detector: Rtx-1 30m, 0.32mm ID, 1.0 μm 70 o C Isothermal Helium at 20 cm/sec ml/min 5.91 psig Split FID 1. acetone 56 o C bp 2. pentane 36 o C 3. propanol 97 o C 4. MEK 80 o C 5. hexane 69 o C 6. butanol 118 o C 7. 3-pentanone 101 o C 8. heptane 98 o C 9. pentanol 138 o C 10. octane 126 o C

5 Rtx-1 100% polydimethyl siloxane Alcohols 2,3 Run Conditions: Dimensions: Temperature: Carrier Gas: Flow: Head Pressure : Injection: Detector: Rtx-1 30m, 0.32mm ID, 1.0 μm 70 o C Isothermal Helium at 20 cm/sec ml/min 5.91 psig Split FID 1. acetone 56 o C bp 2. pentane 36 o C 3. propanol 97 o C 4. MEK 80 o C 5. hexane 69 o C 6. butanol 118 o C 7. 3-pentanone 101 o C 8. heptane 98 o C 9. pentanol 138 o C 10. octane 126 o C

6 Rtx-1 100% polydimethyl siloxane 2,3 Run Conditions: Dimensions: Temperature: Carrier Gas: Flow: Head Pressure : Injection: Detector: Rtx-1 30m, 0.32mm ID, 1.0 μm 70 o C Isothermal Helium at 20 cm/sec ml/min 5.91 psig Split FID 1. acetone 56 o C bp 2. pentane 36 o C 3. propanol 97 o C 4. MEK 80 o C 5. hexane 69 o C 6. butanol 118 o C 7. 3-pentanone 101 o C 8. heptane 98 o C 9. pentanol 138 o C 10. octane 126 o C

7 Separation is according to boiling point Need to add something.... within a certain class of compounds..

8 What about polar phases?

9 PEG 100% poly ethylene glycol Run Conditions: Dimensions: Temperature: Carrier Gas: Flow: Head Pressure : Injection: Detector: Stabilwax 30m, 0.32mm ID, 1.0 μm 70 o C Isothermal Helium at 20 cm/sec ml/min 5.91 psig Split FID 1. pentane 36 o C bp 2. hexane 69 o C 3. heptane 98 o C 4. octane 126 o C 5. acetone 56 o C 6. MEK 80 o C 7. 3-pentanone 101 o C 8. propanol 97 o C 9. butanol 118 o C 10. pentanol 138 o C Polar phases also separate according to to boiling point..

10 Where are boiling point separations used? Simulated Distillation Improved characterization of crude leads to better control of final product Increased gas oil yield

11 Simulated Distillation Chromatographic procedure designed to mimic (simulate) the physical process of distilling petroleum products Establishes a FAST correlation between retention time and boiling point Results are used to control refining operations Results are also an indicator of the range of products that can be produced from a starting material and their potential yield

12 Simulated Distillation The The chromatogram of of the the sample is is divided into into time time slices The The software determines the the area area count for for each slice slice Retention time

13 Retention Time vs Boiling Point

14 Simulated Distillation: ASTM methods Methods can be be classified by by Boiling Point and Hydrocarbon ranges ASTM nr Range Column Injection D2887 C6-C um PDMS 10/0.53 concentr. D7213 (2887-ext) C8-C um PDMS diluted D3710 gasoline up to C um PDMS 10/0.53 concentr. D5307 crude up to C um PDMS, 5/0.53 diluted D6352 C10-C um PDMS, 5/0.53 diluted D7500 C7-C um PDMS, 5/0.53 diluted D7169 C5-C um PDMS, 5/0.53 diluted

15 Challenges in Simulated Distillation Columns Break (fused silica) Columns loose stationary phase by bleed Need to do often calibrations (time) Replace columns (price per analysis, time) Reduced accuracy (reliability challenge) Columns are not efficient Do not meet resolution requirements

16 High temperature separations: column materials Aluminium coated Glass Capillary High temperature Polyimide coated MXT Capillary

polyimide damage Column life time is dictated by the OUTSIDE

17 Problem with fused silica columns used for High temperatures Operation at temperatures of 400ºC or higher will result in polyimide damage Column life time is dictated by the OUTSIDE coating; Column life time not predictable Coupling with PressTight connections is not possible

18 Special High temperature polyimide was developed for highest temperature stability

19 Better solutions MXT metal tubing: extreme strong Virtually unbreakable, self straightening Stable up to 450ºC Can be bended / coiled on small radius Stabilizes the stationary phase winded on standard column cages For Simdist a MUST to use 0.53mm

20 Bleed comparison using different surface deactivations SAME stationary phase, DIFFERENT surface.. Normal deactivation Siltek-deac surface Siltek coated surfaces bleed a factor 4-5 less

21 Use of Sil phenylene phases O CH 3 Si CH 3 CH 3 Si O Si CH 3 CH 3 CH 3 X Y Silphenylene stabilized phases cannot be used for simdist separations The Sil-phenylene will provide some polarity, which causes deviations of calibration curve.. Need to use 100% PDMS, to be able to use historical reference values. Stabilization done by increase of X-links in PDMS chain

22 Simulated Distillation: ASTM methods Methods can be be classified by by Boiling Point and Hydrocarbon ranges ASTM nr Range Column Injection D2887 C6-C um PDMS 10/0.53 concentr. D3710 gasoline up to C um PDMS 10/0.53 concentr. D7213 (2887-ext) C8-C um PDMS diluted D5307 crude up to C um PDMS, 5/0.53 diluted D6352 C10-C um PDMS, 5/0.53 diluted D7500 C7-C um PDMS, 5/0.53 diluted D7169 C5-C um PDMS, 5/0.53 diluted

23 Column Performance-ASTM D7169 Column :: 5m 5m x 0.53mm MXT MXT Simdist, μm μm Oven Oven :: 40 C 40 C C, C, 1 min, min, 30 C/min C104

24 Restek MXT columns show low bleed, because Siltek surface stabilizes the PDMS phase Each column is tested with this test to guarantee performance..

25 Oil spill Mississippi Canyon Block 252

26 Analysis of Tar balls/crude

28 Basic rule in GC stationary phase selection.. Solubility of of sample component in in the stationary phase based upon likes dissolve likes. choose a stationary phase that looks like the components you want to separate.. Hydrocarbons 100% PDMS type phase: Rtx-1 ASTM 6730: detailed hydrocarbon analysis; Many components (>500)

29 GC-FID Hydrocarbons on Rtx-DHA-100 C3 n-c n-c n-c n-c Column : 100 x 0.25 mm Rtx-DHA 100 Oven : 5 C, 10 min -> 50 C, 5 C/min, 54 min, --> 200 C, 1.3 C/min Carrier gas : He, 24 cm/s, 39.3 Psi; Injection Split, 1 : 150; Detection : FID; n-c9 n-c10 n-c

30 Compensate by using Selective detection.. Only see what I want to see.. MS-SIM, SClD/FPD/PFPD, AED, NPD, ECD, O-FID,.. Can use non-polar columns, also shorter in length Efficiency / selectivity less important Challenges: Quenching / Bias Stability and Cost of ownership Need qualified people

31 GC-MS In GC-MS 95% of the applications are done with a non-polar type stationary phases: 100% poly dimethyl siloxane (Rxi-1ms) Arylene modified equivalent of 5% diphenyl /95% dimethyl siloxane (Rxi-5ms and Rxi-5Sil MS) If If there is is a co-elution, the MS will deconvolute if if the mass spectra have clear different m/z fragments

32 For the best quantitative result you need to optimize the separation first.. It s always better to quantify the individual analyte as matrix effects are eliminated Selective detection is nice but we always have to think of the possible bias..

33 2001 Las Vegas ISCC

34 Column Selection Back to Basics.. Rudi Kaiser

35 When need Selectivity? If there are limited nr of plates available; If components have to be separated by nonselective detection If components have same fragments in MS or cause a bias if selective detection is not selective enough.. In multi dimensional separations

36 When need Stationary Phase Selectivity? Limited nr of Plates

37 Limited number of plates Using packed columns plates; Lots of different stationary phases

38 No No deed for for glass columns as as metal is is more inert inert due due to to Siltek deactivation

39 When need Stationary Phase Selectivity? If components have to be separated by non-selective detection

40 Use of non selective detectors FID is widely used: Cheap detector, but requires chromatographic separation Column selectivity is very important: need to use tools available: Use literature search Use Chrom databases on the web from suppliers (Agilent, Restek, Sigma..) Use Chrom calculators and Optimization Chrom calculators

41 Example of Chromatogram Calculator On-line EZ-GC Chromatogram modeler

45 Shortest time analysis Uses available databases

46 Compound structure information + Physical constants Mass spectra data Synonyms

47 On-Line Method translator Flow calculator Will also be a windows application This will be available SOON.. Watch for the Restek news

48 When need Stationary Phase Selectivity? If components have same fragments in MS or cause a bias

49 When components are isobaric, and show similar mass spectra When component forms many similar ions (PCB, Dioxins, BFRs, PAH) GC separation is is essential

50 Separation of PAH in food NIST SRM 2260a on 40m x 0.18mm x 0.07µm Rxi PAH EPA

51 PAH in Food: Chrysene-Triphenylene

52 PAH in Food: Benzo fluoranthenes

53 Complex sample using GC/MS Environmental method, TO components, 4 retentive phases 1-ms 5Sil MS 5-ms VMS Bias: -1ms : ethyl acetate and hexane overlap; share some of the same ions. -5ms/5SilMS : MEK and hexane overlap, share some of the same ions. VMS separates all

54 When need Stationary Phase Selectivity? If Selectivity of Detector is not selective enough..

55 Selective Detection Only see what I want to see.. Is not always possible as selectivity has limitations. Impurity in main product If main component elutes together with Target analyte Quenching: signal of target is impacted by main analyte

56 COS in propylene/propane For trace sulfur, 100% PDMS is preferred. On this phase COS elutes together with Propane/propylene

57 Need selective phase to separate COS from propylene/propane Polar Polar Porous Porous polymer, polymer, type type U, U, 30m 30m x x 0.32mm 0.32mm ID ID x x μm μm H2S COS, 1 ppm propane ethane Propylene elutes with propane on the Rt-UBOND Expected position of ethylene

58 When need Stationary Phase Selectivity? Multidimensional Separations

59 Where else do I need selectivity? If I do not get enough separation on my non-polar column.. Very complex samples, need high peak capacity.. Use column switching Valves Deans (live)

60 Every major Instrument supplier offers a flow switching solution

61 Biodiesel fuel dilution in Lube oil by Flow Heart cut GC PDMS column WAX column

62 Where else do I need selectivity? If I do not get enough separation on my non-polar column.. Very complex samples, need high peak capacity.. Or use column switching

GC x GC Enhanced peak capacity Peak capacity in in GC xgc = 1000 x 30 30 = 30.

63 GC x GC Enhanced peak capacity Peak capacity in in GC xgc = 1000 x = To get equal peak capacity, we would need a 10 km column: Analysis times > weeks

Typical GC x GC Setup Primary column (1 st dimension) Typical 30m x 0.25mm, film of 0.25-0.

secondary column Secondary column (2 nd dimension) Typical 1-2m, 0.15-0.18mm, 0.15/0.

64 Typical GC x GC Setup Primary column (1 st dimension) Typical 30m x 0.25mm, film of um Non-polar Modulator Focuses effluent from primary column Injects this effluent onto secondary column Secondary column (2 nd dimension) Typical 1-2m, mm, 0.15/0.18um Polar or Selective Need to use selectivity to separate components that coelute in the first dimension

65 Selectivities mostly used First dimension: Non-Polar : Rxi-1ms, -5ms, -5Sil MS Polar : Rxi-17Sil MS Second dimension: Liquid phases - Rxi-1ms - Rxi-5Sil MS -Rxi-XLB - Rxi-17Sil MS - Rtx StabilWax -Cyano Shape selective phases Cyclodextrin modifications Liquid crystal Ionic Liquids Major Challenge: temperature stability

66 Nigerian Crude on GCxGC-TOF-MS 1.1m x 0.15 mm id. x 0.15 μm -17Sil-MS Range ºC 30m x 0.25mm x 0.25 μm non-polar 5Sil MS

67 BFr s en PCB s Pesticides Rxi-17Sil MS Rtx-200 Rxi-XLB Rxi-5Sil MS Rtx-1ms Hydrocarbon oils First column Second column Rxi-5ms Terpenes cannabinoids : non-polar : polar cannabinoids Rxi-17Sil MS Rxi-17Sil MS

68 BFr s en PCB s Pesticides Rxi-17Sil MS First column Rtx-200 : polar Second column : non-polar Rxi-XLB Rxi-5Sil MS Hydrocarbon oils Terpenes cannabinoids Rtx-1ms Rxi-5ms cannabinoids Rxi-17Sil MS Rxi-17Sil MS

69 Basic rule in GC stationary phase.. Solubility of of sample component in in the stationary phase based upon likes dissolve likes. choose a stationary phase that looks like the components you want to separate.. Hydrocarbons 100% PDMS Rtx-1 Aromatic subst. Phenyl subst. PDMS Rtx-5, 17Sil, 35Sil Halogenates Arom. Fluorimated-phenyl Rtx-440, Cl-Pesticides, Rtx-200 Solvents Cyano /phenyl Rtx-1301/624Sil Alcohols,diols,glycols PEG Stablewax/Rtx-wax Double bonds Cyano propyl Rt 2330, 2460

70 (GC-MS) Presence of Diethylene Glycol and Ethylene Glycol in Toothpaste Phase: PEG Dissolves : likes like

71 Important note on Selectivity behavior: It changes with temperature Liquid phases: By lower elution temperatures the phase behaves LESS polar Solid phases By lower elution temperatures the phase behaves MORE polar This effect is is the biggest with POLAR stationary phases.. Peak elution can change..

72 Non-Polar phase: 100% PDMS column; different temperature programs: Analysis of a Naphtha mixture 30 C/min 155ºC 1-mNap C/min 130ºC 7 min C/min 115ºC 12 min m 2 C/min 1 C/min 95ºC 81ºC 19 min Some Some components are are very very sensitive for for changes in in elution 33 min elution temperature C/min 68ºC 50 min 72 min

73 Medium polarity: Optimized phase for Cl-Pesticides Peak elution reversal At At psi, psi, u = cm/s cm/s 4,4 -DDE Endosulfan I Tel. Tel. = 250ºC 250ºC At At psi, psi, u = cm/s Endosulfan I 4,4 -DDE Tel. Tel. = 210ºC 210ºC

74 Polar column: TCEP Relative elution of benzene to C11 and C12 30ºC Benzene RI=1090 C11 C12 50ºC C11 benzene C12 70ºC benzene C11 C12 90ºC C11 C12 benzene 110ºC C11 C12 C12 Benzene RI = 1240

75 Temperature effect on selectivity using Al2O3/Na2SO4

76 Impact of Flow rate on separation; Rt Alumina BOND / MAPD Higher flow = lower elution temperature 100kPa propadiene C4 acetylene 150kPa C4 propadiene acetylene 200kPa C4 propadiene acetylene

77 Relative position of CO changes with temperature 40 ºC CH4 Column Column Carrier Carrier Split Split Detection Detection : : 1m 1m x x 0.53mm 0.53mm MXT MXT Molsieve Molsieve 5A 5A 80/100 80/100 mesh mesh : : He, He, kpa kpa : : 1 1 : : 30; 30; Injection: Injection: μl; μl; Sample: Sample: 2-5% 2-5% in in He He : : micro-tcd micro-tcd CO 80 ºC 4 min CH4 CO 120 ºC 1.4 min CH4 CO 0.8 min

78 Summary A boiling point column will only separate according to boiling point if the same class of compounds are considered Columns with different selectivity s will be essential for running many applications even using selective detection systems Choosing selectivity will remain a challenge as we depend on data. More tools will be developed in future to help us. Additional, selectivity is temperature dependent which means there is another factor that plays a role.

79 If you want to learn Chromatography? Visit the Restek ChromaBLOGraphy.. A LOT of information shared by Restek scientists that allow you to get better in your chromatography..

80 Use the Search option.. If you want to know about: what do chromatograms tell us? Just search on what do chromatograms.. you can get a full list with links.. and

81 Thanks you for participating If your any question, please drop me an

Introduction and Principles of Gas Chromatography

Introduction and Principles of Gas Chromatography Jaap de Zeeuw Restek, Middelburg, The Netherlands Jaap.dezeeuw@restek.com Definition and Uses of Gas Chromatography GC Components and Types of Columns