Slide 1: Finding the Perfect Match: Practical Advice on GC Column Selection
Finding the Perfect Match: Practical Advice on GC Column Selection Alexander Ucci Online Application Engineer September 12, 2019 Finding the Perfect Match: Practical Advice on GC Column Selection 1 September 12, 2019 Agilent Restricted
Slide 2: Things to Consider when Choosing a Column
Things to Consider when Choosing a Column • Is it volatile enough to chromatograph by GC? • Is it a gas or a liquid? • How are we getting the sample injected? • What is the sample matrix? -Can we do sample clean up? • Is it an established method? • What do we know about the analytes? • What else may
Slide 3: Some Column History
Some Column History 1969: 1977: First glass capillary columns 1979: First WCOT fused silica capillary columns Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 4: Capillary Column Types
Capillary Column Types Porous Layer Open Tube (PLOT) Solid Carrier gas particles Wall Coated Open Tube (WCOT) Carrier gas Liquid phase 4 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 5: Column Construction
Column Construction Polyimide coating Flexible polymeric coating; adds mechanical strength and temperature stability to fused silica Fused silica Amorphous glass-like tubing comprised of silicon dioxide; high temperature resistance, low reactivity. May contain rough edges creating active sites. Deac
Slide 6: Stationary Phase Polymers
Stationary Phase Polymers R= methyl, phenyl, cyanopropyl, trifluoropropyl % = number of sites on silicon atoms occupied Siloxane Siarylene backbone Structure of Agilent J&W HP-5ms 5% phenyl / 95% methyl Polyethylene glycol 6 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent
Slide 7: Polyethylene Glycol Phases
Polyethylene Glycol Phases HO CH2 CH2 O H n • Less stable than polysiloxanes • Unique separation characteristics • Popular WAX phases from Agilent - Most inert: Agilent J&W DB-WAX UI - High temperatures: Agilent J&W DB-HeavyWAX - Application specific: Agilent J&W DB-FATWAX UI 7 Finding the Perfect M
Slide 8: Another New Column: J&W DB-HeavyWAX
Another New Column: J&W DB-HeavyWAX The WAX column you’ve been waiting for! • Increase temperature range - 280 °C isothermal - 290 °C programmed • Increased thermal stability - Stable retention times - Consistent peak order • Lower bleed - Greater sensitivity for “heavier” compounds - Increased anal
Slide 9: Bleed Summary at 280°C Over Hours
Bleed Summary at 280°C Over 100 Hours pA 90 Column Bleed over 100 hours 80 70 WAX A at 100 Hours WAX A 70 60 WAX B 60 WAX B at 100 Hours 50 50 40 Bleed (pA) WAX B at 0 Hours 40 30 30 WAX A at 0 Hours 20 20 10 DB-HeavyWAX DB-HeavyWAX at 100 hours 10 DB-HeavyWAX at 0 hours 0 0 20 40 60 80 100 0 1 2 3
Slide 10: J&W Column Portfolio - DB, HP, CP, VF
JW Column Portfolio- DB, HP, CP, VF Low Polarity Mid Polarity High Polarity CP-Sil 2 DB & HP-1MS UI DB & HP-5MS UI DB-XLB DB-225MS DB-ALC1 HP-88 DB-WAX DB-WAX UI DB-MTBE DB & HP1-MS DB & HP5-MS VF-XMS DB-225 DB-Dioxin CP-Sil 88 DB-WAX ETR DB-HeavyWAX CP-Select CB MTBE VF-1MS VF-5MS DB-35MS UI CP-Sil
Slide 11: Specialty Phases
Specialty Phases Columns developed for particular applications • Examples: - DB-8270D UI - DB-624 UI <467> - DB-MTBE - DB-TPH - DB-BAC1 UI & DB-BAC2 UI - DB-HT SimDis - Select Low Sulfur - CP-Volamine - Select PAH - DB-EUPAH - DB-CLP1 & DB-CLP2 - DB-Select 624 UI <467> - CP-LowOx - Select Permanent
Slide 12: High Temperature Applications
High Temperature Applications Semi-volatiles 100 °C 350 °C Volatiles -10 °C 200 °C Crude oil residues Finished petroleum products Waxes 400/450 °C Polymer additives Industrial chemicals Dyes 40 °C 400 °C Flavor and fragrances 40 °C 280 °C Sterols Food products Triglycerides 40 °C 380 °C If you aren’
Slide 13: Agilent's High Temperature Columns
Peak Name Agilent’s High Temperature Columns Tridecane 3500 0 Methane Agilent J&W DB-5HT 1 Decane 3000 2 1-Octanol 2500 3 2,6-Dimethylphenol 4 2,6-Dimethylaniline plates/meter 2000 pA 5 Naphthalene 0 1 90 1500 6 1-Decanol 80 7 Tridecane 1000 3 8 Methyl Decanoate 70 2 500 60 5 Competitor P 50 4 0 0 2
Slide 14: Low Bleed Phases
Low Bleed Phases •Phases tailored to “mimic” currently existing polymers Examples: DB-5ms, DB-35ms, DB-17ms, VF-1701ms R R R R Si Si Si Si O O O R n R R R m Siarylene backbone •New phases unrelated to any previously existing polymers Examples: DB-XLB •Optimized manufacturing processes Examples: DB-1
Slide 15: What is Column Bleed?
What is Column Bleed? “Back biting” mechanism of product formation H3C CH3 Si HO O CH3 CH3 CH3 CH3 CH3 Si O Si O Si O Si O Si Si CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH O CH3 Si O Si O Si O Si O Si O Si O Si OH 3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 + Si O Si O Si O Si OH H3C CH3 C
Slide 16: Agilent J&W DB-5ms Structure
Agilent J&W DB-5ms Structure CH3 DB-5 structure DB-5ms structure O Si CH3 CH3 Si CH3 O O Si CH3 Si CH3 O Si CH3 CH3 Si CH3 CH3 O O Si CH3 CH3 CH3 Si DB-5ms: • Increased stability • Different selectivity • Optimized to match DB-5 as much as possible 16 Finding the Perfect Match: Practical Advice on G
Slide 17: DB-5ms vs. DB-5 Selectivity
DB-5ms vs. DB-5 Selectivity Chromatograms are offset on x-axis for easier viewing Solid line: Agilent J&W DB-5ms 30 m x .25 mm id x .25 mm Dashed line: Agilent J&W DB-5 30 m x .25 mm id x .25 mm Oven: 60 oC isothermal Carrier gas: H2 at 40 cm/sec 1: Ethylbenzene 2: m-Xylene 3: p-Xylene 4: o-Xylene 1
Slide 18: Comparison of Agilent J&W DB-35MS vs Standard DB-35
Comparison of Agilent J&W DB-35MS vs Standard DB-35 1400000 Standard 35% Phenyl 1200000 1000000 800000 Benzo[g,h,i]perylene (1 ng) 600000 400000 200000 DB-35ms 10.00 12.00 14.00 16.00 18.00 20.00 22.00 Group/Presentation Title Agilent Restricted Finding the Perfect Match: Practical Advice on GC Colu
Slide 19: Agilent Ultra Inert GC Columns
Agilent Ultra Inert GC Columns Column inertness: what does it mean? • Easier to describe “lack of inertness” - Peak tailing (reversible interaction) - Loss of compound all together (irreversible interaction) • A high level of flow path inertness will produce peaks from active compounds that are not
Slide 20: DB-WAX Ultra Inert and Free Fatty Acids
DB-WAX Ultra Inert and Free Fatty Acids Peak identification: 1. Methane 2. Acetone (solvent) 3. Acetic acid 4. Propionic acid 5. Isobutyric acid 6. Butyric acid 7. Isovaleric acid 8. Valeric acid 9. 4-Methylvaleric acid 10. Hexanoic acid 11. 4-Methylhexanoic acid 12. 2-Ethylhexanoic acid 13. Heptano
Slide 21: Let's Make a Better Wax Column: DB-WAX Ultra Inert
Let’s Make a Better Wax Column: DB-WAX Ultra Inert Competitor comparison DB-WAX UI test mix after 50 hours at 250 °C Compound I.D. *. Methane 1. 5-Nonanone 2. Decanal 3. Propionic Acid Competitor 1 4. Ethylene Glycol 5. Heptadecane 6. Aniline 7. Methyl Dodecanoate Competitor 2 8. 2-Chlorophenol 9. 1
Slide 22: Ultra Inert Test Mix – DB-5MS Ultra Inert v. Competitors
Ultra Inert Test Mix – DB-5MS Ultra Inert v. Competitors pA 5 18 2 3 1. 1-Propionic acid 16 8 2. 1-Octene 14 3. n-Octane 4 11 4 4-Picoline 12 9 10 Competitor 5. n-Nonane 10 1 column 6. Trimethyl phosphate 8 7 6 7. 1,2-Pentanediol 0 2 4 6 8 10 min pA 5 8. n-Propylbenzene 20 3 2 9. 1-Heptanol 18 4 8 1
Slide 23: Why is Stationary Phase Type Important?
Why is Stationary Phase Type Important? N k - 1 Rs = 4 k +1 Influence on α k2 = k2 = partition ratio of 2nd peak k1 k1 = partition ratio of 1st peak Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 24: Selectivity
Selectivity • Relative spacing of the chromatographic peaks • The result of all non-polar, polarizable and polar interactions that cause a stationary phase to be more or less retentive to one analyte than another Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 25: Optimizing Selectivity
Optimizing Selectivity () • Match analyte polarity to stationary phase polarity - “Like dissolves like” • Take advantage of unique interactions between analyte and stationary phase functional groups Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 26: Analyte Polarity
Analyte Polarity Nonpolar molecules - generally composed of only carbon and hydrogen and exhibit no dipole moment (Straight-chained hydrocarbons (n-alkanes)) Polar molecules - primarily composed of carbon and hydrogen but also contain atoms of nitrogen, oxygen, phosphorus, sulfur, or a halogen (Alco
Slide 27: Selectivity Interactions
Selectivity Interactions • Dispersion • Dipole • Hydrogen bonding 27 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 28: Dispersion Interaction (ΔHvap)
Dispersion Interaction ( DHvap ) • Separation by differences in analyte heat of vaporizations ( DHvap ) • Heat necessary to convert a liquid into a gas (at the same temperature) 28 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 29: Dispersion Interaction
Dispersion Interaction Hexanol 158oC Solubility And Retention Decane 174oC Dodecane 216oC C10 C12 Hexanol 100% Methyl (non-polar) 0 2 4 6 8 C10 C12 Hexanol 100% PEG (polar) 0 2 4 6 8 30 m x 0.32 mm id, 0.25 µm He at 35 cm/sec 50–170 °C at 15 °C/min 29 Finding the Perfect Match: Practical Advice on G
Slide 30: Dispersion Interaction (ΔHvap)
Dispersion Interaction ( DHvap ) Vapor pressure: good approximation Boiling point: poor approximation 30 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 31: Dipole Interaction
Dipole Interaction C18:1 (Methyl trans-9-octadecenoate) B.Pt. 186°C C18:1 (Methyl cis-9-octadecenoate) B.Pt. 186°C Smaller differences require a stronger dipole phase 31 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 32: DB-FastFAME cis/trans isomer separation
Strong interaction between cis DB-FastFAME isomers and the dipoles of the 20 m x 0.18 mm x 0.20 μm cyano propyl ligands. That allows the trans to elute after the cis isomers. Cis Trans Column Agilent J&W DB-FastFAME, 20 m x 0.18 mm, 0.20 µm Gas Hydrogen, 28 psi, constant pressure mode RS ≥ 1.95 for
Slide 33: Hydrogen Bonding Interaction
Hydrogen Bonding Interaction Dipole-Dipole interaction with hydrogen bound to oxygen or nitrogen interacting with an oxygen or nitrogen-atom + - H H O O H H 33 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 34: Nonpolar Phases
Nonpolar Phases Characterized by 100% polydimethylsiloxanes such as HP-1, DB-1, DB-1ms, HP-1ms,VF-1ms, CP-Sil 5 CB Me Si O Me n Separation mechanisms: • Dispersion only 34 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 35: Polarizable Phases
Polarizable Phases Typified by phenyl substituted siloxanes, substituted at 5–50% (HP-5, HP-5ms, DB-35, DB-35ms, DB-17, DB-17ms) Ph Me O Si O Si O 5%--weakly polar, 50%-- mid-polar Ph Me m n Separation mechanisms: • Dispersion • Inducible dipole at phenyl groups 35 Finding the Perfect Match: Practic
Slide 36: Strong Dipole Phases
Strong Dipole Phases Typified by cyanopropyl or trifluoropropyl substituted siloxanes, substituted 6–50% (DB-1701, DB-1301, DB-200, DB-23, DB-225) R Me R = cyanopropyl or trifluoropropyl O Si O Si O R = phenyl or methyl R' Me m n Separation mechanisms: • Dispersion • Inducible dipole at phenyl grou
Slide 37: Hydrogen Bonding Phases
Hydrogen Bonding Phases Typified by polyethylene glycol polymers (HP-Innowax, DB-WAX UI, DB-HeavyWAX, DB-FFAP, VF-WAXms, CP-WAX52CB…) H H HO - - C-C-O- -H H H n Separation mechanisms: • Dispersion • Strong permanent dipole • Hydrogen bonding 37 Finding the Perfect Match: Practical Advice on GC Colum
Slide 38: Selectivity
Selectivity Interaction strengths Phase Dispersion Dipole H Bonding Methyl Strong None None Phenyl Strong None Weak Cyanopropyl Strong Very Strong Moderate Trifluoropropyl Strong Moderate Weak PEG Strong Strong Moderate 38 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Re
Slide 39: Polarity
Polarity Polarity Stability Temperature Range 39 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 40: Compounds & Properties
Compounds & Properties Hydrogen Compounds Polar Aromatic Dipole Bonding Toluene no yes no induced Hexanol yes no yes yes Phenol yes yes yes yes Decane no no no no Naphthalene no yes no induced Dodecane no no no no 40 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restrict
Slide 41: 100% Methyl Polysiloxane
100% Methyl Polysiloxane 2 1. Toluene 110 oC 1 3 2. Hexanol 156 oC 6 3. Phenol 182 oC 4 4. Decane (C10) 174 oC 5 5. Naphthalene 218 oC 6. Dodecane (C12) 216 oC Strong dispersion No dipole No hydrogen bonding 0 2 4 6 8 10 12 14 16 41 Finding the Perfect Match: Practical Advice on GC Column Selection
Slide 42: 5% Phenyl
CompoundsPolar Aromatic Hydrogen Bonding Dipole 5% Phenyl Toluene Hexanol no yes yes no no yes induced yes Phenol yes yes yes yes Decane no no no no Naphthalene no yes no induced 5,6 Dodecane no no no no 1 2 4 3 Strong dispersion No dipole 5% Phenyl Weak hydrogen bonding 0 2 4 6 8 10 12 14 16 1. Tol
Slide 43: 50% Phenyl
CompoundsPolar Aromatic Hydrogen Bonding Dipole 50% Phenyl Toluene Hexanol no yes yes no no yes induced yes Phenol yes yes yes yes Decane no no no no Naphthalene no yes no induced 1 2 Dodecane no no no no 4 3 6 5 50% Phenyl Strong dispersion No dipole Weak hydrogen bonding 0 2 4 6 8 10 12 14 16 ? 2
Slide 44: 14% Cyanopropylphenyl
Compounds Polar Aromatic Hydrogen 14% Cyanopropylphenyl Toluene no yes Bonding no Dipole induced Hexanol yes no yes yes Phenol yes yes yes yes Decane no no no no 1 Naphthalene no yes no induced 24 6 Dodecane no no no no 3 14% Cyano- 5 Strong dispersion None/strong dipole (phenyl/cyanopropyl) propylp
Slide 45: 50% Cyanopropyl
Compounds Polar Aromatic Hydrogen Dipole 50% Cyanopropyl Toluene no yes Bonding no induced Hexanol yes no yes yes Phenol yes yes yes yes Decane no no no no 6 Naphthalene no yes no induced 4 2 Dodecane no no no no 1 5 3 Strong dispersion 50% Strong dipole Cyanopropyl Moderate hydrogen bonding 0 2 4 6
Slide 46: 100% Polyethylene Glycol
Hydrogen 100% Polyethylene Glycol Compounds Polar Toluene no Aromatic yes Bonding no Dipole induced Strong dispersion Hexanol yes no yes yes Strong dipole Phenol yes yes yes yes Decane no no no no 4 Moderate hydrogen bonding Naphthalene no yes no induced 1 6 Dodecane no no no no 2 5 3 100% PEG 0 2 4
Slide 47: Stationary Phase Selection
Stationary Phase Selection Part 1 • Existing information • Selectivity • Polarity • Critical separations • Temperature limits 47 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 48: Agilent Bond Elut Sample Cleanup Products
Agilent Bond Elut Sample Cleanup Products Filtration cartridges and plates Solid Phase Extraction cartridges and plates Synthetic Chem Elut S Captiva EMR Lipid Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 49: Captiva EMR–Lipid Cleanup Improves Analytes S/N Ratio and Integration Accuracy
Captiva EMR–Lipid Cleanup Improves Analytes S/N Ratio and Integration Accuracy on GC/MS(/MS) of Pesticides in Olive Oil Pesticide Captan Permethrin Deltamethrin EMR-Lipid cleanup Zirconia sorbent cleanup + MRM (151.0 -> 79.1) Post-S 50ppb Fatty dSPE C1-3.D Counts x10 5 1.4 1.2 1 C18/PSA 0.8 0.6 clea
Slide 50: Stationary Phase Selection
Stationary Phase Selection Part 2 • Capacity • Analysis time • Bleed • Versatility • Selective detectors 50 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 51: Column Dimensions
Column Dimensions • Inner diameter • Length • Film thickness 51 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 52: Column Diameter
Column Diameter Capillary Columns id (mm) Common Name 0.53 Megabore 0.45 High speed megabore 0.32 Wide 0.20–0.25 Narrow 0.18 Minibore 52 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 53: Column Diameter: Theoretical Efficiency
Column Diameter Theoretical Efficiency id (mm) N/m 0.10 11905 0.18 6666 0.20 5941 0.25 4762 0.32 3717 k=5 0.53 2242 53 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 54: Efficiency and Resolution
Efficiency and Resolution Relationship N Rs efficiency x 4 = resolution x 2 54 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 55: Column Diameter Resolution
Column Diameter Resolution (180 °C isothermal) R= 0.87 R= 1.01 n =58,700 n =107,250 0.53 mm 0.32 mm Square root of resolution is inversely proportional to column diameter 55 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 56: Column Diameter: Inlet Head Pressures
Column Diameter Inlet head pressures for 30 meter column (helium) id (mm) Pressure (psig) 0.10 225–250 0.20 25–35 0.25 15–25 0.32 10–20 0.53 2–4 Hydrogen would produce about half the amount of pressure 56 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 57: Column Diameter: Capacity
Column Diameter Capacity (0.25 µm film thickness) id (mm) Capacity (ng) 0.20 50–100 0.25 75–150 0.32 125–250 0.53 200–400 Like polarity phase/solute 57 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 58: Column Diameter: Carrier gas flow rate
Column Diameter Carrier gas flow rate Smaller diameters for low flow situations (e.g., GC/MS) Larger diameters for high flow situations (e.g., purge & trap, headspace, gas sample valve) 58 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 59: Column Length
Column Length Most common: 15–60 meters Available: 5–200 meters 59 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 60: Column Length: Resolution and Retention
Column Length Resolution and retention 210°C isothermal R= 0.84 R= 1.16 R= 1.68 2.29 min 4.82 min 8.73 min 15 m 30 m 60 m Resolution is proportional to the square root of column length Isothermal: retention is proportional to length Temperature program: 1/3–1/2 of isothermal values 60 Finding the Pe
Slide 61: Column Length and Cost
Column Length and Cost 15 meters 30 meters 60 meters 61 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 62: Film Thickness
Film Thickness Most common: 0.1–3.0 µm Available: 0.1–10.0 µm 62 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 63: Film Thickness and Retention (100°C Isothermal)
Film Thickness and Retention (100°C Isothermal) 7.00 minutes 0.25 µm 0 2 4 6 8 24.59 minutes 1.00 µm 0 5 10 15 20 25 Isothermal: Retention is proportional to film thickness Temperature program: 1/3–1/2 of isothermal values 63 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent
Slide 64: Film Thickness: Equal Retention
Film Thickness Equal Retention: Isothermal 100°C 7.00 minutes 0.25 µm 0 2 4 6 8 137°C 7.08 minutes 1.00 µm 0 2 4 6 8 Agilent J&W DB-1, 30 m x 0.32 mm id He at 37 cm/sec C10, C11, C12 64 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 65: Film Thickness and Resolution
Film Thickness and Resolution When solute k < 5 d f R When solute k > 5 d f R 65 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 66: Film Thickness: Resolution at low k
Film Thickness Resolution at low k 0.25 µm 2.0 min 1.2 1.4 1.6 1.8 1.00 µm 3.5 min 2 3 3.00 µm 6.5 min 2 4 6 DB-1, 30 m x 0.32 mm id 40 °C isothermal, He at 35 cm/sec Solvent mixture 66 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 67: Film Thickness: Resolution at high k
Film Thickness Resolution at high k R=0 k = 0.09 0.25 µm 2.2 min 1.900 2.000 2.100 2.200 R = 0.81 k = 2.55 1.00 µm 5.0 min 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0 R = 0.72 k = 13.46 5.00 µm 18.0 min 10 12 14 16 18 DB-1, 30 m x 0.32 mm id 40 °C isothermal, He at 35 cm/sec Solvent mixture 67 Finding the Perfe
Slide 68: Film Thickness (Capacity)
Film Thickness (Capacity) Thickness (µm) Capacity (ng) 0.10 50-100 0.25 125-250 1.0 500-1000 3.0 1500-3000 0.32 mm column id 5.0 2500-5000 Like polarity phase/solute 68 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 69: Film Thickness (Bleed)
Film Thickness (Bleed) More stationary phase = More degradation products 69 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 70: Film Thickness (Inertness)
Film Thickness (Inertness) 0.25 µm 1.0 µm 3.0 µm active inactive active inactive active inactive 70 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 71: Column Dimensions: Diameter summary
Column Dimensions Diameter summary To Increase Make Diameter Resolution Smaller Retention Smaller Pressure Smaller Flow rate Larger Capacity Larger 71 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 72: Column Dimensions: Length summary
Column Dimensions Length summary To Increase Make Length Resolution Longer Retention Longer Pressure Longer Cost Longer 72 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 73: Column Dimensions: Film thickness summary
Column Dimensions Film thickness summary To Increase Make Film Retention Thicker Resolution (k<5) Thicker Resolution (k>5) Thinner Capacity Thicker Inertness Thicker Bleed Thicker 73 Finding the Perfect Match: Practical Advice on GC Column Selection Agilent Restricted
Slide 74: Example of Changing Dimensions to Achieve Faster Chromatography (Before)
Example of Changing Dimensions to Achieve Faster Chromatography Before Column: DB-WAX 30 m x 0.25 mm x 0.25 µm Carrier: Helium at 25.4 cm/sec measured at 45 oC Oven: 45 oC for 2 min 45 to 250 oC at 3 oC/min 250 oC for 34 min Injector: Split 1:30, 250 oC 1 µL of 1:35 oil in Acetone Detector: MSD full
Slide 75: Example of Changing Dimensions to Achieve Faster Chromatography (After)
Example of Changing Dimensions to Achieve Faster Chromatography After Column: DB-WAX 20 m x 0.18 mm x 0.18 µm Carrier: Helium at 26.3 cm/sec measured at 45 oC Oven: 45 oC for 1.28 min 45 to 250 oC at 4.67 oC/min 250 oC for 21.81 min Injector: Split 1:30, 250 oC 1 µL of 1:35 Oil in Acetone Detector:
Slide 76: Conclusions
Conclusions • Understand the sample • Is it volatile and thermally stable enough to chromatograph by GC? • Try to match polarity – oil and water don’t mix! • Look for unique characteristics of compounds and match them to a phase • If you have the correct selectivity, change the dimensions to improve
Slide 77: Contact Agilent Chemistries and Supplies Technical Support
Contact Agilent Chemistries and Supplies Technical Support 1-800-227-9770 Option 3, Option 3: Option 1 for GC and GC/MS columns and supplies Option 2 for LC and LC/MS columns and supplies Option 3 for sample preparation, filtration, and QuEChERS Option 4 for spectroscopy supplies Option 5 for chemic