GC Resolution Do You See What I See? Column Dimensions and Carrier Gas Optimization Deans Switch Page 1
Variables for Maximizing Resolution Optimized Stationary Phase Longer Column Length Decrease Internal Diameter Carrier Gas: type and linear velocity Optimized Temperature Programming Page 2
Resolution N k Rs = 4 k 1 a 1 a Efficiency Retention Selectivity N = (gas, L, r c ) k = (T, d f, r c ) a = (T, phase) L = Length r c = column radius d f = film thickness T = temperature Page 3
WCOT Column Types Agilent J&W has over 50 different stationary phase offerings Page 4
FactorFour TM Phases VF-1ms, VF-5ms, VF-5ht, VF-5ht UltiMetal VF-17ms, VF-17ms for PAH, VF-35ms, VF-200ms,VF-Xms, VF-23ms, VF-624ms, VF-DA, VF-1301ms, VF-Pesticides, VF-1701ms, VF-WAXms Page 5
20+ Different Specialty Phases Specialty phases are columns that are optimized to perform a specialized GC analysis. Column Typical Application DB-624 EPA and USP volatiles DB-VRX volatiles analysis HP-VOC volatiles analysis DB-502.2 EPA Method 502.2 DB-5.625 EPA semi-volatiles analysis DB-608 EPA Method 608 DB-1701P EPA pesticides analysis DB-MTBE total petroleum hydrocarbon (TPH) HP-PONA petroleum hydrocarbon analysis DB-HT SimDis hi-temp simulated distillation DB-ALC1 & ALC2 blood alcohol analysis HP-88 fatty acid methyl ester (FAME) Page 6
Select TM Column Examples Environmental applications CP-Sil 88 for dioxins, Select mineral oil, CP-Select 624 CB Chiral applications CP-Chirasil Val, CP-Chirasil-DEX CB Chemical applications CP-Volamine, CP-Select CB for MTBE, CP-PONA C8, CP-Propox, Select Silanes, CP-SimDist UltiMetal TM, CP-Lowox TM Food and Beverage applications CB-Carbowax 400, Select FAME, CP-Sil 88 for FAME, CP-FFAP CB Page 7
PLOT Column Types PLOT columns are primarily, but not exclusively, used for the analysis of gases and low boiling point solutes (i.e., boiling point of solute is at or below room temperature). Agilent J&W PLOT columns begin with the designation of GS (Gas Solid) or HP-PLOT followed by a specific name 10 stationary phases GS-OxyPLOT GS-Alumina HP-PLOT Al2O3 M HP-PLOT Al2O3 S HP-PLOT Al2O3 KCl GS-OxyPLOT: oxygenates HP-PLOT Molesieve: O2, N2, CO, Methane HP-PLOT Alumina and GS-Alumina: complex hydrocarbon gas matrices, ethylene and propylene purity, 1,4-butadiene HP-PLOT Q: freons, sulfides HP-PLOT U: C1 to C7 hydrocarbons, CO2, Polar Hydrocarbons GS-GasPro: freons, sulfurs, inorganic gases GS-CarbonPLOT: inorganic and organic gases HP-PLOT MoleSieve GS-CarbonPLOT HP-PLOT Q HP-PLOT U GS-GasPro Page 8
PLOT GC Columns from Varian Line Porous Polymers CP-PoraBOND Q CP-PoraBOND U CP-PoraPLOT Q CP-PoraPLOT U CP-PoraPLOT S CP-PoraPLOT Q-HT CP-PoraPLOT amines Zeolites Molsieve 5A Molsieve 13x Alumina KCL Na 2 SO4 MAPD Multi Layer CP-Lowox Porous Silica SilicaPLOT Graphatised Carbon CP-CarboPLOT P7 CP-CarboBOND Select TM permanent gases Page 9
Optimizing Selectivity Match analyte polarity to stationary phase polarity -like dissolves like (oil and water don t mix) Take advantage of unique interactions between analyte and stationary phase functional groups Page 10
Stationary Phase Selection Existing Information Critical Separations Selectivity/Polarity Temperature Limits Application Designed Examples: DB-CLP1, DB-CLP2, DB-UI 8270D, DB-624UI, DB-Select 624UI<467>, DB-VRX, HP-VOC, DB-MTBE, Lowox, DB-TPH, DB-HTSimDis, DB-2887, DB-HT SimDis, CP-Volamines, DB-ALC1, DB-ALC2, Select Phases, etc. Choose the column phase that gives the best separation but not at the cost of robustness or ruggedness. Page 11
Complete Resolution & Fast CLP Pesticide Analysis Page 12
Agilent J&W DB-CLP1 and DB-CLP2 For 9 EPA Methods+ (More than any other CLP column pair!) Page 13
Selectivity Differences DB-VRX DB-624 Page 14
Benzene and 1,2-Dichloroethane Separation DB-624 DB-Select 624UI<467> Co-elution 30m x 0.53mm 30m x 0.32mm Page 15
Benzene and 1,2-Dichloroethane Separation DB-Select 624UI<467> Baseline Resolved R= 1.82 Vendor R G43 Vendor P G43 R= 1.59 R= 1.38 All 30m x 0.32mm
Resolution N k Rs = 4 k 1 a 1 a Efficiency Retention Selectivity N = (gas, L, r c ) k = (T, d f, r c ) a = (T, phase) L = Length r c = column radius d f = film thickness T = temperature Page 17
Column Diameter - Theoretical Efficiency I.D. (mm) n/m 0.05 23,160 0.10 11,980 0.18 6,660 0.20 5830 0.25 4630 0.32 3760 0.45 2840 k = 5 0.53 2060 Page 18
Different Column I. D. Equal Phase Ratios Column : DB-624 30 m, 0.53 mm, 3 m Carrier: Helium, 40 (cm/sec) Oven: 65 C Injection: Split Detector: FID Column : DB-624 30 m, 0.32 mm, 1.8 m 0 5 10 15 20 Time (min) Page 19
PHASE RATIO ( ) Film Thickness Column Dimensions Phase Ratio β 30 m x.53 mm x 3.0 m 44 30 m x.32 mm x 1.8 m 44 K C = k β β = r 2d f Page 20
High Resolution Megabore Same Resolution - Faster Analysis! Increasing Sample Throughput With High-Speed Megabore Application note 5988-5271EN Page 21
Column Diameter and Capacity I.D. (mm) Capacity (ng) 0.05 1-2 0.10 6-13 0.18 25-55 0.20 35-70 0.25 80-160 0.32 110-220 0.45 600-800 0.53 1000-2000 Like Polarity Phase/Solute 0.25 µm film thickness Page 22
Column Length and Efficiency (Theoretical Plates) 0.25 mm ID n/m = 4630 (for k = 5) Length (m) N 15 69,450 30 138,900 60 277,800 More Meters = More Plates = More Resolution Page 23
Column Length and Resolution R a N a L Length X 4 = Resolution X 2 t a L Upside = Cut a bunch off during routine inlet maintenance and not lose a lot of Resolution Page 24
Column Length VS Resolution and Retention: Isothermal R=0.84 2.29 min R=1.16 4.82 min R=1.68 8.73 min 15 m 30 m 60 m Double the plates, double the time but not double the the resolution Page 25
Column Length and Cost 15m 30m 60m $ $ $ $ $ $ $ Page 26
Resolution N k Rs = 4 k 1 a 1 a Efficiency Retention Selectivity N = (gas, L, r c ) k = (T, d f, r c ) a = (T, phase) L = Length r c = column radius d f = film thickness T = temperature Page 27
Carrier Gas Maximum Resolution = Optimum Velocity = Slowest Velocity Van Deemter Curves 1.00 Excessive Diffusion N 2 h 0.75 0.50 He Poor Mass Transfer 0.25 ū opt H 2 10 20 30 40 50 60 u (cm/sec) Page 28
Carrier Gas Type Nitrogen Helium Hydrogen Velocity Range (u opt OPGV) 10-17 cm/sec 22-40 cm/sec 35-55 cm/sec Page 29
Changes in Column Dimensions, Gas Type or Velocity Require Changes in Temp Program Rates Method Translation Software to the Rescue! Page 30
Phenol s 30m x 0.25mm ID, 0.25μm, DB-5ms Check Valleys Page 31
Phenol s 20m x 0.18mm ID, 0.18μm, DB-5ms 0.54 ml/min, H2 (~47cm/sec) Page 32
Slower than Best Efficiency? must go faster! (Sorry customer doesn t want temperature program revealed) Page 33
Phenol s 20m x 0.18mm ID, 0.18μm, DB-5ms 1 ml/min, (rounded up?) higher than optimum, BUT still better Resolution! Page 34
Original Method 1 2 3 G C 3-6 7 0 7. D \ E C D 2 B 4 5,6 7 8 10 9 11 12 13 14 Column: DB-XLB 30m x 0.32mm i.d., 0.25µm Carrier: He, constant flow, 38 cm/s at 120 C Injector: Pulsed Splittless, 220 C Pulse pressure & time: 35psi for 1.15min Oven: 15 16 18 2µL, 50ppb 120 C for 1.17min 120 C to 160 C at 25 /min 160 C to 260 C at 10 /min 260 C to 300 C (4min) at 15 /min Detector: µ-ecd, 320 C Ar/CH4 (P5) makeup gas at 60mL/min 19 21 <16 minutes 22 17 20 6. 0 0 8. 0 0 1 0. 0 0 1 2. 0 0 1 4. 0 0 1 6. 0 0 Page 35
Best Efficiency New Velocity (SLOWER) New Temp. Program (SLOWER) Page 36
Best Efficiency Better Resolution 6. 0 0 8. 0 0 1 0. 0 0 NEW Original 23 minutes (Slower)
Resolution N k Rs = 4 k 1 a 1 a Efficiency Retention Selectivity N = (gas, L, r c ) k = (T, d f, r c ) a = (T, phase) Temperature, the TRUMP card L = Length r c = column radius d f = film thickness T = temperature Page 38
Column Temperature Optimizing Temperature Programs Most powerful variable Changes Selectivity and Retention Natural log (ln) relationship between retention and temperature Most difficult to predict and develop Often involves trial and error (Sorry) Page 39
Capillary Flow Technology Capabilities Backflushing with Purged Devices 2D GC Deans Switch / Heart Cutting Splitter to Multiple Detectors Multiple Columns/Multiple Detectors Page 40
Purged Capillary Flow Devices 2-Way Splitter with Makeup 3-Way Splitter with Makeup Deans Switch Purged Union (most recent) Page 41
Heart Cutting 2-D GC How It Works Valve off, no heart cutting inject sample, initial separation on column 1 FID A 6.54 ml/min << 1mL/min Restrictor Off S/S Inlet purge PCM 4.54 ml/min restrictor 9.78 psi 11.14 psi Column 1 FID B 6.54 ml/min 2mL/min 8.54 ml/min Column 2 Page 42
Heart Cutting 2-D GC How It Works Valve on start heart cut from column 1 to column 2 FID A 6.54 ml/min 2mL/min 8.54 ml/min Restrictor purge restrictor S/S Inlet PCM 4.54 ml/min 9.78 psi 11.14 psi Column 1 On FID B 6.54 ml/min << 1mL/min Column 2 Page 43
Heart Cutting 2-D GC How It Works Valve off end heart cut, perform 2 nd separation on column 2 FID A 6.54 ml/min << 1mL/min Restrictor purge restrictor S/S Inlet PCM 4.54 ml/min 9.78 psi 11.14 psi Column 1 BP>Benzene Off FID B 6.54 ml/min 2mL/min 8.54 ml/min Column 2 Page 44
Page 45 Calculator - Set Flows and Restrictor Size
Trace Thiophene in Benzene Need to measure 0.02 to 2.00 mg/kg thiophene in pure benzene benzene HP-Innowax Column 60m x 0.53mm x 0.5um 2.09 mg/kg thiophene 4 5 6 7 8 9 10 11 12 Page 46
Trace Thiophene in Benzene Analysis of 20 ppb to 2 ppm using FID (2 ul splitless injection) benzene 500 400 300 200 100 hydrocarbons toluene Cut window 7.74-8.02 min 1,4-dioxane Innowax Column Analytical Precision (15 runs over 5 days) 0 0.6 0.5 0.4 0.3 0.2 0.1 4 6 8 10 12 14 16 18 20 HP Plot Q Column 50 ppb thiophene 4 6 8 10 12 14 16 18 20 Avg Amt: 50 ppb Std Dev: 0.95 ppb RSD: 1.9% Page 47
Agilent s Ultimate Pesticide Analysis System 1 gas chromatograph 1 injection FPD µecd MS SIM MS Scan Page 48
Pesticides: Three Way Splitter with Makeup 1X method with 1:1:0.1 split FPD:MSD:ECD Auto-sampler Phosphorus FPD AUX EPC 3.8 psig uecd 3-Way Splitter with Makeup 7890 GC Column 30 m X 0.25 mm id X 0.25 um HP-5MS 5975C MSD Page 49
3-Way Splitter System Deactivated splitter operates to 350 C. Using metal ferrules eliminates leaks and retightening To FPD To MSD To µecd Column in Makeup gas from EPC Page 50
Milk Extract (1 injection) Full scan TIC SIM µecd FPD(P) 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 Page 51
LTM and Capillary Flow Technology, Possibilities! Metabolomics Crops Research (Polar and Non-polar Analytes) R-1 Three Way Splitter Two Way Splitter HP-5ms Main Oven R-2 R-3 FID Front Inlet Deans Switch R-4 MSD DB-17ms LTM AUX 1 AUX 2 AUX 3 Back Inlet Pre Column DB-1ms LTM HP-5ms 30m x 0.25 x 0.25 19091S-433 à Column 1 DB-1ms 15m x 0.25 x 0.25 122-0112 à Column 2 R1 = 0.30m x 0.1 restrictor à Column 4 R2 = 0.17m x 0.1 restrictor à Column 5 R3 = 0.50m x 0.25 restrictor à to FID R4 = 1.00m x 0.18 restrictor à Column 3 HP-5ms 30m x 0.25 x 0.25 19091S-433 (Column 1) DB-17ms LTM 15m x 0.25 x 0.25 122-4712LTM DB-1ms LTM 15m x 0.25 x 0.25 122-0112LTM (Column 2) Pre-Column = 1m x 0.25 uncoated FS Page 52
Finally the Ultra Inert Story All that resolution is worth nothing if the peaks start tailing and/or disappearing! Ultra Inert Columns and Liners provide the maximum inertness available on the market. Activity only gets worse once you start injecting samples. Start as inert as you can. Page 53
Ultra Inert liners Touchless packaging Easy installation of new, clean liner without risk of contamination from touching Includes non-stick plasma treated O-ring Page 54
Ultra Inert Test Mix - DB-5ms Ultra Inert vs. competitors 1. 1-Propionic acid 2. 1-Octene 3. n-octane 4 4-Picoline 5. n-nonane 6. Trimethyl phosphate 7. 1,2-Pentanediol 8. n-propylbenzene 9. 1-Heptanol 10. 3-Octanone 11. n-decane pa 18 16 14 12 10 8 18 16 14 12 10 8 6 0 2 4 6 8 10 pa 27.5 25 22.5 20 17.5 15 12.5 10 1 1 1 2 2 2 3 3 3 4 4 4 5 5 pa 0 2 4 6 8 10 20 5 6 6 7 7 7 6 8 8 8 9 9 10 10 11 11 9 10 11 Competitor Column min Competitor Column min Agilent J&W DB- 5ms Ultra Inert 30m x 0.25mm x 0.25um (P/N 122-5532UI) 0 2 4 6 8 10 min Page 55
Semivolatiles Prone to Peak Tailing (App. Note 5990-3416EN) Page 56
Semivolatiles Prone to Peak Tailing (App. Note 5990-3416EN) Page 57
Resolution of benzo-b & k fluoranthene isomers Abundance 1500000 Benzo-b-fluoranthene Benzo-k-fluoranthene 1000000 Resolution of 1.2 500000 100000 0 19.00 19.50 Time--> As good as it gets it only gets worse! Page 58
Conclusions for Better Resolution in GC Application Specific Stationary Phase - tuned for max R Smaller Diameter - loss in capacity, so small changes Longer, More Plates - big changes needed since it has a small effect and it increases analysis times Optimum Carrier Gas Velocity - slowest carrier gas velocity 2D GC - more chromatographic space but adds complexity Multiple columns, inlets, detectors - single system with LTM and Capillary Flow Technology Sharp Peaks - tailing, broadening, etc. loses resolution Page 59
ANY QUESTIONS? Technical Support 1-800-227-9770, 3,3,1 E-mail: gc_column_support@agilent.com Page 60