GC Resolution Do You See What I See?

Transcription

1 GC Resolution Do You See What I See? Column Dimensions and Carrier Gas Optimization Deans Switch Page 1

2 Variables for Maximizing Resolution Optimized Stationary Phase Longer Column Length Decrease Internal Diameter Carrier Gas: type and linear velocity Optimized Temperature Programming Page 2

3 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

4 WCOT Column Types Agilent J&W has over 50 different stationary phase offerings Page 4

5 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

6 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 EPA Method DB 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

7 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

8 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

9 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

10 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

11 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

12 Complete Resolution & Fast CLP Pesticide Analysis Page 12

13 Agilent J&W DB-CLP1 and DB-CLP2 For 9 EPA Methods+ (More than any other CLP column pair!) Page 13

14 Selectivity Differences DB-VRX DB-624 Page 14

15 Benzene and 1,2-Dichloroethane Separation DB-624 DB-Select 624UI<467> Co-elution 30m x 0.53mm 30m x 0.32mm Page 15

16 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

17 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

18 Column Diameter - Theoretical Efficiency I.D. (mm) n/m , , , k = Page 18

19 Different Column I. D. Equal Phase Ratios Column : DB m, 0.53 mm, 3 m Carrier: Helium, 40 (cm/sec) Oven: 65 C Injection: Split Detector: FID Column : DB m, 0.32 mm, 1.8 m Time (min) Page 19

20 PHASE RATIO ( ) Film Thickness Column Dimensions Phase Ratio β 30 m x.53 mm x 3.0 m m x.32 mm x 1.8 m 44 K C = k β β = r 2d f Page 20

21 High Resolution Megabore Same Resolution - Faster Analysis! Increasing Sample Throughput With High-Speed Megabore Application note EN Page 21

22 Column Diameter and Capacity I.D. (mm) Capacity (ng) Like Polarity Phase/Solute 0.25 µm film thickness Page 22

23 Column Length and Efficiency (Theoretical Plates) 0.25 mm ID n/m = 4630 (for k = 5) Length (m) N 15 69, , ,800 More Meters = More Plates = More Resolution Page 23

24 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

25 Column Length VS Resolution and Retention: Isothermal R= min R= min R= min 15 m 30 m 60 m Double the plates, double the time but not double the the resolution Page 25

26 Column Length and Cost 15m 30m 60m $ $ $ $ $ $ $ Page 26

27 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

28 Carrier Gas Maximum Resolution = Optimum Velocity = Slowest Velocity Van Deemter Curves 1.00 Excessive Diffusion N 2 h He Poor Mass Transfer 0.25 ū opt H u (cm/sec) Page 28

29 Carrier Gas Type Nitrogen Helium Hydrogen Velocity Range (u opt OPGV) cm/sec cm/sec cm/sec Page 29

30 Changes in Column Dimensions, Gas Type or Velocity Require Changes in Temp Program Rates Method Translation Software to the Rescue! Page 30

31 Phenol s 30m x 0.25mm ID, 0.25μm, DB-5ms Check Valleys Page 31

32 Phenol s 20m x 0.18mm ID, 0.18μm, DB-5ms 0.54 ml/min, H2 (~47cm/sec) Page 32

33 Slower than Best Efficiency? must go faster! (Sorry customer doesn t want temperature program revealed) Page 33

34 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

35 Original Method G C D \ E C D 2 B 4 5, 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: µL, 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 <16 minutes Page 35

36 Best Efficiency New Velocity (SLOWER) New Temp. Program (SLOWER) Page 36

37 Best Efficiency Better Resolution NEW Original 23 minutes (Slower)

38 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

39 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

40 Capillary Flow Technology Capabilities Backflushing with Purged Devices 2D GC Deans Switch / Heart Cutting Splitter to Multiple Detectors Multiple Columns/Multiple Detectors Page 40

41 Purged Capillary Flow Devices 2-Way Splitter with Makeup 3-Way Splitter with Makeup Deans Switch Purged Union (most recent) Page 41

42 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 psi Column 1 FID B 6.54 ml/min 2mL/min 8.54 ml/min Column 2 Page 42

43 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 psi Column 1 On FID B 6.54 ml/min << 1mL/min Column 2 Page 43

44 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 psi Column 1 BP>Benzene Off FID B 6.54 ml/min 2mL/min 8.54 ml/min Column 2 Page 44

45 Page 45 Calculator - Set Flows and Restrictor Size

46 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 Page 46

47 Trace Thiophene in Benzene Analysis of 20 ppb to 2 ppm using FID (2 ul splitless injection) benzene hydrocarbons toluene Cut window min 1,4-dioxane Innowax Column Analytical Precision (15 runs over 5 days) HP Plot Q Column 50 ppb thiophene Avg Amt: 50 ppb Std Dev: 0.95 ppb RSD: 1.9% Page 47

48 Agilent s Ultimate Pesticide Analysis System 1 gas chromatograph 1 injection FPD µecd MS SIM MS Scan Page 48

49 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

50 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

51 Milk Extract (1 injection) Full scan TIC SIM µecd FPD(P) Page 51

52 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 S-433 à Column 1 DB-1ms 15m x 0.25 x 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 S-433 (Column 1) DB-17ms LTM 15m x 0.25 x LTM DB-1ms LTM 15m x 0.25 x LTM (Column 2) Pre-Column = 1m x 0.25 uncoated FS Page 52

53 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

54 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

55 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 Octanone 11. n-decane pa pa pa Competitor Column min Competitor Column min Agilent J&W DB- 5ms Ultra Inert 30m x 0.25mm x 0.25um (P/N UI) min Page 55

56 Semivolatiles Prone to Peak Tailing (App. Note EN) Page 56

57 Semivolatiles Prone to Peak Tailing (App. Note EN) Page 57

58 Resolution of benzo-b & k fluoranthene isomers Abundance Benzo-b-fluoranthene Benzo-k-fluoranthene Resolution of Time--> As good as it gets it only gets worse! Page 58

59 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

60 ANY QUESTIONS? Technical Support , 3,3,1 Page 60