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The van Deemter Indoctrination
 

The van Deemter Indoctrination

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Nitrogen cannot be used as carrier gas for GC. How sure are you about that? In this presentation we tackle what we call the “van Deemter indoctrination”. Take a look at our recent accomplishments ...

Nitrogen cannot be used as carrier gas for GC. How sure are you about that? In this presentation we tackle what we call the “van Deemter indoctrination”. Take a look at our recent accomplishments and convince yourself to give it at try. Particularly now when more and more laboratories are suffering from inconsistent supplies of helium.

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    The van Deemter Indoctrination The van Deemter Indoctrination Presentation Transcript

    • THE VAN DEEMTERINDOCTRINATIONNitrogen as Carrier Gas for GC? Are you kidding! www.is-x.be
    • This is a funny story…
    • This is a funny story…about carrier gases in GC…
    • This is a funny story…about carrier gases in GC…and how we all got fooled.
    • Are you ready?
    • Keep staring in the center
    • Keep staring in the center
    • Keep staring in the center
    • You are suffering frominconsistent helium supply
    • You have problemsimplementing hydrogen
    • There isNO ALTERNATIVE !!!!!
    • We all know this story,don’t we?
    • However…
    • Have you ever considerednitrogen?
    • Probably not…
    • That’s because we all suffer from the “van Deemter indoctrination” Don’t worry, I’ve been a victim myself too…
    • Take a look at our experiences and try to cure yourself too!
    • J. J. van Deemter was a briljant Dutch physicist.He worked for the Royal Dutch Shell laboratoryIn Amsterdam (The Netherlands) in the 1950s.He was employed as chemical engineer and onlyhad little direct interest in chromatography.
    • In those days, the mathematical description ofthe chromatography process was rather complex.
    • In those days, the mathematical description ofthe chromatography process was rather complex.This was mainly due to improper modelling.
    • However, after much experimentation and plotting,a very simple equation could be derived. van Deemter J. J., Zuiderweg F. J. & Klinkenberg A.“Longitudinal diffusion and resistance to mass transfer as causes of nonideality in chromatography.” Chem. Eng. Sci. 5:271-89, 1956.
    • This equation, which is known as the van Deemterequation, was the first to describe the chromato-graphic process correctly.
    • H = A + B/u + CuH = height of one theoretical plate, cmu = average linear velocity, cm/s
    • H = A + B/u + CuIn order to work under optimal conditions,plate height H has to be minimal.
    • THE A TERM = EDDY DIFFUSIONPeak broadening due to path lenghts differences in packedGC columns. A = 0 for capillary columns.
    • THE A TERM = EDDY DIFFUSIONPeak broadening due to path lenghts differences in packedGC columns. A = 0 for capillary columns.
    • THE A TERM = EDDY DIFFUSIONPeak broadening due to path lenghts differences in packedGC columns. A = 0 for capillary columns.
    • THE A TERM = EDDY DIFFUSIONPeak broadening due to path lenghts differences in packedGC columns. A = 0 for capillary columns.
    • THE A TERM = EDDY DIFFUSIONPeak broadening due to path lenghts differences in packedGC columns. A = 0 for capillary columns.
    • THE B TERM = LONGITUDINAL DIFFUSIONPeak broadening due to multidirectional diffusion.Indirectly proportional to flowrate.
    • THE B TERM = LONGITUDINAL DIFFUSIONPeak broadening due to multidirectional diffusion.Indirectly proportional to flowrate.
    • THE B TERM = LONGITUDINAL DIFFUSIONPeak broadening due to multidirectional diffusion.Indirectly proportional to flowrate.
    • THE B TERM = LONGITUDINAL DIFFUSIONPeak broadening due to multidirectional diffusion.Indirectly proportional to flowrate.
    • THE C TERM = RESISTANCE TO MASS TRANSFERPeak broadening due to equilibrium kinetics in mobile andstationary phase. Directly proportional to flowrate! flowrate! Stationary phase
    • THE C TERM = RESISTANCE TO MASS TRANSFERPeak broadening due to equilibrium kinetics in mobile andstationary phase. Directly proportional to flowrate! flowrate! Stationary phase
    • THE C TERM = RESISTANCE TO MASS TRANSFERPeak broadening due to equilibrium kinetics in mobile andstationary phase. Directly proportional to flowrate! flowrate! Stationary phase
    • THE C TERM = RESISTANCE TO MASS TRANSFERPeak broadening due to equilibrium kinetics in mobile andstationary phase. Directly proportional to flowrate! flowrate! Stationary phase
    • Both B and C terms react opposite to flowratechanges.
    • Both B and C terms react opposite to flowratechanges.There is an optimal flow!
    • This is how a typical van Deemter curve looks like. 3,5 3 2,5 2 H, cm 1,5 1 0,5 0 0 0,5 1 1,5 2 2,5 Flow rate, mL/min
    • And this is the optimal flow region. 3,5 3 Optimal flow region 2,5 2 H, cm 1,5 1 0,5 0 0 0,5 1 1,5 2 2,5 Flow rate, mL/min
    • Key variables that determine curve shape and optimalflow region are column ID and carrier gas type.
    • Key variables that determine curve shape and optimalflow region are column ID and carrier gas type.
    • Key variables that determine curve shape and optimalflow region are column ID and carrier gas type.
    • Influence of carrier gas type. 3,0 Nitrogen 2,5 2,0 H, cm 1,5 Helium 1,0 Hydrogen 0,5 0,0 0 0,5 1 1,5 2 2,5 Flow rate, mL/min
    • Experimental details. 3,0 Test compound: 2-ethyl hexanoic acid Nitrogen 2,5 Column: 20 m x 0.18 mm I.D. x 0.18 µm df Phase: Rxi-5 Sil MS Manufacturer: Restek (# 43602) 2,0 H, cm 1,5 Helium 1,0 Hydrogen 0,5 0,0 0 0,5 1 1,5 2 2,5 Flow rate, mL/min
    • Van Deemter tells us: “helium is acceptable”.
    • Van Deemter tells us: “helium is acceptable”.We advise to use helium for all MS applications,but do we really need it for GC/FID work ?
    • Van Deemter tells us: “hydrogen is best”.
    • Van Deemter tells us: “hydrogen is best”.We advise to use hydrogen for fast(er) GCapplications. In combination with MS you have tocope with a loss in sensitivity and a risk of activity.
    • Approach when keeping the same column:
    • Approach when keeping the same column:Divide the isothermal stages of your oven programby two and double all the programming rates (headpressure stays the same).
    • Approach when keeping the same column:Divide the isothermal stages of your oven programby two and double all the programming rates (headpressure stays the same). Thus: 30C (2 min) to 250C at 10C/min (Helium) = 30C (1 min) to 250C at 20C/min (Hydrogen)
    • Example 1: Solvent impurity analysis.
    • Example 1: Solvent impurity analysis. TRACE GC-F ID A Un kn own Helium: 30 minutes 120000 120000 110000 110000 100000 100000 90000 90000 80000 70000 80000 70000 Column: 20 m x 0.18 mm I.D. 60000 60000 A Ap p 50000 50000 40000 40000 30000 30000 20000 20000 10000 10000 0 0 -10000 -10000 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 Minutes
    • Example 1: Solvent impurity analysis. TRACE GC-F ID A Un kn own Helium: 30 minutes 120000 120000 110000 110000 100000 100000 90000 90000 80000 70000 80000 70000 Column: 20 m x 0.18 mm I.D. 60000 60000 A Ap p 50000 50000 40000 40000 30000 30000 20000 20000 10000 10000 0 0 -10000 -10000 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 Minutes 160000 TRACE GC-F ID A 160000 Hydrogen: 15 minutes Un kn own 150000 150000 140000 140000 130000 130000 120000 120000 110000 100000 90000 110000 100000 90000 Column: 20 m x 0.18 mm I.D. 80000 80000 A Ap p 70000 70000 60000 60000 50000 50000 40000 40000 30000 30000 20000 20000 10000 10000 0 0 -10000 -10000 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Minutes
    • A little bit more in detail.
    • A little bit more in detail. 12 14 16 Minut es Helium
    • A little bit more in detail. 12 14 16 6 7 8 Minut es Helium Hydrogen
    • Example 2: Process analysis.
    • Example 2: Process analysis. FID1 A, (1603JV04.D) FID2 B, (1603JV04.D) 0.898 pA 7 6.5 6 5.5 5 4.5 4 3.5 0 2 4 6 8 10 12 min
    • Example 2: Process analysis. FID1 A, (1603JV04.D) FID2 B, (1603JV04.D) 0.898 pA 7 6.5 6 5.5 5 4.5 4 3.5 0 2 4 6 8 10 12 min Helium: 44 minutes Hydrogen: 14 minutes! MXT column: 10 m x 0.53 mm I.D.
    • Example 3: Environmental analysis
    • Example 3: Environmental analysis TRACE GC-FID-ar SV MegaMix 42.5 42.5 40.0 40.0 37.5 37.5 35.0 35.0 32.5 32.5 30.0 30.0 27.5 27.5pA pA 25.0 25.0 22.5 22.5 20.0 20.0 17.5 17.5 15.0 15.0 12.5 12.5 10.0 10.0 7.5 7.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 Minutes
    • Example 3: Environmental analysis TRACE GC-FID-ar SV MegaMix 42.5 42.5 40.0 40.0 37.5 37.5 35.0 35.0 32.5 32.5 30.0 30.0 27.5 27.5pA pA 25.0 25.0 22.5 22.5 20.0 20.0 17.5 17.5 15.0 15.0 12.5 12.5 10.0 7.5 10.0 7.5 Helium: 25 minutes 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Minutes 3.5 4.0 4.5 5.0 5.5 6.0 Column: 20 m x 0.18 mm I.D. Hydrogen: 6 minutes! Column: 10 m x 0.10 mm I.D.
    • But beware,
    • But beware,It’s a struggle to convice company safety officers.
    • But beware,It’s a struggle to convice company safety officers.You need to invest in sensors.
    • But beware,It’s a struggle to convice company safety officers.You need to invest in sensors.You need to invest in generators.
    • But beware,It’s a struggle to convice company safety officers.You need to invest in sensors.You need to invest in generators.And sometimes it simply does not work!
    • Example 1: Loss in capacity. TRACE GC-FID-AR TRACE GC-FID-AR TRACE GC-FID-AR 28 cumeen cumeen cumeen 28 5-10-2009 13-35-40 CP5CB H2 cumeen.dat 24-09-2009 10-11-54 CC656 H2 cumeen.dat 29-09-2009 12-36-21 CC657 H2 cumeen.dat Retention Time Name 3,682 26 26 24 0.15 mm ID, 24 22 0.6 µm df (H2) 22 20 20 18 18 3,443 0.15 mm ID, pA pA 16 16 1.2 µm df (H2) 14 14 12 12 10 10 3,588 8 8 4,000 3,797 6 6 3,380 4 3,2 3,3 3,4 Reference: 3,5 3,6 3,7 3,8 3,9 4,0 4,1 4,2 4 Minutes 0.32 mm ID, 1.2 µm df (H2)
    • Example 2: Impurities in styrene. Styrene Ethylbenzene
    • Example 2: Impurities in styrene. Styrene Ethylbenzene
    • Results overview. Ethylbenzene (He) Ethylbenzene (H2) Indane (He) Indane (H2) 1000 900 800 700 Conc, ppm 600 500 400 300 200 100 0 250 230 210 190 170 150 Injection temp, C
    • Results overview. Ethylbenzene (He) Ethylbenzene (H2) Indane (He) Indane (H2) 1000 900 800 700 Conc, ppm Internal standard 600 500 400 300 200 100 0 250 230 210 190 170 150 Injection temp, C
    • Results overview. Ethylbenzene (He) Ethylbenzene (H2) Indane (He) Indane (H2) 1000 900 800 700 Conc, ppm 600 500 Ethylbenzene 400 300 200 100 0 250 230 210 190 170 150 Injection temp, C
    • And finally…
    • Last but not least…
    • Nitrogen…
    • Van Deemter tells us: “nitrogen cannot be used”.
    • Van Deemter tells us: “nitrogen cannot be used”. Is this where it ends?
    • Van Deemter tells us: “nitrogen cannot be used”. Is this where it ends?
    • We have implemented several nitrogen methodssuccessfully the last year.
    • We have implemented several nitrogen methodssuccessfully the last year.We primarely aim at GC/FID methods.
    • We have implemented several nitrogen methodssuccessfully the last year.We primarely aim at GC/FID methods.
    • We have implemented several nitrogen methodssuccessfully the last year.We primarely aim at GC/FID methods. 7/10 instruments!
    • Approach when keeping the same column:
    • Approach when keeping the same column:Just leave everything as it is(including head pressure)!
    • Approach when keeping the same column:Just leave everything as it is(including head pressure)! Thus: 30C (2 min) to 250C at 10C/min (Helium) = 30C (2 min) to 250C at 10C/min (Nitrogen)
    • Example 1: Test mix.
    • Example 1: Test mix. Carrier N2 1.5 mL #3 XIL-350_Mix He Front_FID215.00 Helium pA14.00 11 - 4.063 12 - 4.147 14 - 4.785 16 - 4.87313.00 13 - 4.505 15 - 4.827 Column: 20 m x 0.18 mm I.D.12.00 10 - 3.26311.00 8 - 9 - 2.867 2.81510.00 min9.00 2.00 2.20 2.40 2.60 2.80 3.00 3.20 3.40 3.60 3.80 4.00 4.20 4.40 4.60 4.80 5.00
    • Example 1: Test mix. Carrier N2 1.5 mL #3 XIL-350_Mix He Front_FID215.00 Helium pA14.00 11 - 4.063 12 - 4.147 14 - 4.785 16 - 4.87313.00 13 - 4.505 15 - 4.827 Column: 20 m x 0.18 mm I.D.12.00 10 - 3.26311.00 8 - 9 - 2.867 2.81510.00 min 9.00 2.00 2.20 2.40 2.60 2.80 3.00 3.20 3.40 3.60 3.80 4.00 4.20 4.40 4.60 4.80 5.00 Carrier N2 1.5 mL #3 XIL-350_Mix He Front_FID215.00 Nitrogen pA14.00 11 - 4.063 12 - 4.147 14 - 4.785 16 - 4.87313.00 13 - 4.505 15 - 4.827 Column: 20 m x 0.18 mm I.D.12.00 10 - 3.26311.00 8 - 9 - 2.867 2.81510.00 min9.00 2.00 2.20 2.40 2.60 2.80 3.00 3.20 3.40 3.60 3.80 4.00 4.20 4.40 4.60 4.80 5.00
    • Example 2: Butyl acrylate.
    • Example 2: Butyl acrylate. Helium Column: 60 m x 0.32 mm I.D.
    • Example 2: Butyl acrylate. Helium Column: 60 m x 0.32 mm I.D. Nitrogen Column: 60 m x 0.32 mm I.D.
    • A little bit more in detail.
    • A little bit more in detail. Helium
    • A little bit more in detail. Helium Nitrogen
    • A little bit more in detail. Helium Nitrogen
    • Example 3: Narrow bore column
    • Example 3: Narrow bore column Nitrogen Column: 10 m x 0.1 mm I.D. 2.00 min
    • Why does it work?
    • Why does it work?Van Deemter is measured under isothermal conditions
    • Why does it work?Van Deemter is measured under isothermal conditionsVan Deemter is valid for optimal conditions
    • Why does it work?Van Deemter is measured under isothermal conditionsVan Deemter is valid for optimal conditions
    • Why does it work?Van Deemter is measured under isothermal conditionsVan Deemter is valid for optimal conditions Injection Septum Liner Column
    • Why does it work?Van Deemter is measured under isothermal conditionsVan Deemter is valid for optimal conditions Injection Septum Liner Column
    • Other methods: Acrylates Di- and triamines BTEX Non-aromatics Primary aryl alcohols Ethylacetate Ethanolamines Alcohols Acetic acid Light hydrocarbons
    • Don’t be afraid to challengevan Deemter!
    • More information? Dr. Joeri Vercammen IS- Managing Expert IS-X www.is-x.be j.vercammen@is-x.be http://www.linkedin.com/in/joerivercammenAlso check out our other presentations!
    • Acknowledgements: C. De Weerdt E. Van Brussel A. De Caluwé R. Heus P. Ryckaert M. Van Lancker