Practical Faster GC Applications with High-Efficiency GC Columns and Method Translation Software

Transcription

1 Practical Faster GC Applications with High-Efficiency GC Columns and Method Translation Software High Efficiency GC Columns Page 1 Variables for Shortening Run Times Stationary Phase Shorten Column Length Decrease Internal Diameter Temperature Programming Carrier Gas: type and linear velocity Page 2 1

2 Resolution N k R s = α 1 4 k + 1 α Efficiency Retention Selectivity N = ƒ (gas, L, r c ) k = ƒ (T, d f, r c ) α = ƒ (T, phase) L = Length r c = column radius d f = film thickness T = temperature Page 3 Start with the Right Phase DB-1 15m x 0.32mm, 0.25µm Oven: 40 C for 2 min C at 5 C/min Time (min.) DB-Wax 15m, 0.32mm, 0.25µm Oven: C at 20 C/min Time (min.) Page 4 2

3 Resolution N k R s = α 1 4 k + 1 α Efficiency Retention Selectivity N = ƒ (gas, L, r c ) k = ƒ (T, d f, r c ) α = ƒ (T, phase) L = Length r c = column radius d f = film thickness T = temperature Page 5 Column Length and Efficiency (Theoretical Plates) Length (m) n 15 69, , , mm ID n/m = 4630 (for k = 5) Page 6 3

4 Column Length and Resolution R α n α L Length X 4 = Resolution X 2 t α L Page 7 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 8 4

5 DECREASE THE LENGTH DB-5 30 m 0.53 mm I.D., 0.5 µm DB-5 15 m 0.53 mm I.D., 0.5 µm 1. Benzene 2. Toluene 3. Ethylbenzene 4. m,p-xylene 5. o-xylene BTEX Carrier: Helium, 36 cm/sec at 40 c Oven : 40 C for 3 min, 5 /min to 100 C 6.0 Page 9 Column Length and Cost 15m 30m 60m $ $ $ $ $ $ $ Page 10 5

6 Length Summary If you Decrease Length: Efficiency Decrease Resolution Decrease Analysis Time Decrease Pressure Decrease Cost Decrease Page 11 Resolution N k R s = α 1 4 k + 1 α Efficiency Retention Selectivity N = ƒ (gas, L, r c ) k = ƒ (T, d f, r c ) α = ƒ (T, phase) L = Length r c = column radius d f = film thickness T = temperature Page 12 6

7 Column Diameter - Theoretical Efficiency 5 m 10 m Total Plates N ~ 112,000 N ~ 112,000 I.D. (mm) m N ~ 112, n/m 23,160 11,580 6, m N ~ 112, k = Page 13 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 14 7

8 PHASE RATIO (β) Film Thickness Column Dimensions Phase Ratio β 30 m x.53 mm x 3.0 µm m x.32 mm x 1.8 µm 44 K C = k β β = r 2d f Page 15 Column Diameter and Capacity I.D. (mm) Capacity (ng) Like Polarity Phase/Solute 0.25 µm film thickness Page 16 8

9 Diameter Summary If you decrease the inside diameter: Efficiency Increase Resolution Increase Pressure Increase Capacity Decrease Flow rate Decrease Page 17 Combining a change in Length with a change in Diameter Decrease Length Decrease Diameter Efficiency Analysis Time Page 18 9

10 Resolution N k R s = α 1 4 k + 1 α Efficiency Retention Selectivity N = ƒ (gas, L, r c ) k = ƒ (T, d f, r c ) α = ƒ (T, phase) L = Length r c = column radius d f = film thickness T = temperature Page 19 Carrier Gas Considerations Best velocity? Optimal range of velocities Too low or high results in loss of resolution Balance resolution and analysis time BUT... there is no LAW against going FASTER Page 20 10

11 Carrier Gas Considerations Van Deemter Curve 1.00 Excessive Diffusion h He Poor Mass Transfer 0.25 ū opt H 2 OPGV u (cm/sec) Page 21 Carrier Gas - Hydrogen Comments Hydrogen is extremely diffusive in air Difficult to reach explosive level of ~4 % Most GC's flow regulated with safety shutdown Spring loaded/explosion proof doors Page 22 11

12 Carrier Gas Considerations Utilizing Computer Controlled Flow Ramping (EPC) Lonely Late Eluters? = P Decrease retention and overall run time by increasing pressure (speed up the gas!) Page 23 Easy Options with Method Translation Software Different Column Dimensions Switch He to H 2 Carrier Gas and Try Faster Velocities Same Column & Gas Type but Faster Velocities Combination of all of the above Page 24 12

13 CLP-Pesticides - Original Improved Method 0.32mm I.D., Helium Carrier Gas 1 2 GC D\ECD2B 3 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 2µL, 50ppb Oven: 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 25 Input Original Method Parameters Page 26 13

14 Same Column and Gas Type Fast Analysis (OPGV) Transfer same dimensions New Velocity New Temp. Program Page 27 GC D\ECD2B Same Column and Gas Type Fast Analysis (OPGV) Before No Real Changes in Resolution! Only Time! <14 minutes Page 28 14

15 GC D\ECD2B Same Column and Gas type None mode, Try higher velocities New calculated temp. program Page 29 Same Column and Gas type None mode, Higher velocities Before Co-elution (poorer) 80 cm/sec Co-elution (poorer) <8 minutes 65 cm/sec <10 minutes Close elution (similar) 50 cm/sec Page 30 15

16 Same Column, Hydrogen Carrier Gas Translate Only Page 31 GC D\ECD2B Same Column, H 2 Carrier Gas Translate Only Before No Real Changes in Resolution % faster! 11 minutes Page 32 16

17 GC D\ECD2B Same Column, H2 Carrier Gas, Higher Velocities Page 33 Same Column, H2 Carrier Gas, Even Higher Velocities Co-elution Before 85 cm/sec Co-elution 7 minutes 80 cm/sec Co-elution <8 minutes 70 cm/sec Page 34 17

18 New Column Dimensions, H 2 Gas, Translate Only Input NEW dimensions Close enough (got lucky) New Velocity New Temp. Program Page 35 New Column Dimensions, H2 Gas, Translate Only Page 36 18

19 New Column Dimensions, H2 Gas, Translate Only Page 37 New Column Dimensions, H2 Gas, Fast Analysis New Velocity New Temp. Program Page 38 19

20 New Column Dimensions, H2 Gas, Fast Analysis Better Resolution and Faster Analysis! Page 39 New Column Dimensions, H2 Gas, Higher Velocities Page 40 20

21 New Column Dimensions, H2 Gas, Higher Velocities 105 cm/sec? 5.5 minutes! 95 cm/sec <6 minutes 85 cm/sec Page 41 Flow Ramp (EPC) for Late Eluters and Faster Bake Outs Page 42 21

22 Flow Ramp No Flow Ramp Begin of Flow Ramp Under 5 minutes! Page 43 Final Method Used at EPA Column: DB-XLB 20m x 0.18mm i.d., 0.18µm Carrier: H2, constant flow, 77.3cm/s at 120 C Injector: Pulsed Splittless, 220 C Pulse pressure & time: 35psi for 0.5min Flow ramp at 6.25min of 99mL/min 2 to 3mL/min 2mm i.d. liner 0.5µL, 50ppb Oven: 120 C for 0.49min 120 C to 160 C at 59.4 /min C to 260 C at 23.7 /min C to 300 C (1.69min) at 35.6 /min 9 Detector: µ-ecd, 320 C 13 Ar/CH4 (P5) makeup gas at 60mL/min Page 44 22

23 Final Method Used at EPA DB-XLB DB-17ms Page 45 Further Work (App. Note EN) 20m x 0.18mm ID, Fast Even in Helium Page 46 23

24 Translate Only, Helium DB-XLB DB-17ms minutes Page 47 Food/Fragrance Method translation Page 48 24

25 Spearmint Oil on DB min -9.7 min 0.18 mm, He Carrier 0.25 mm, He Carrier 27.4 min Time (min) Page 49 Food/Fragrance Method translation, Hydrogen Page 50 25

26 Spearmint Oil on DB-1, (App. Note EN) 10.6 min min 0.18 mm, H 2 Carrier 17.7 min -9.7 min 0.18 mm, He Carrier 0.25 mm, He Carrier 27.4 min Time (min) Page 51 Spearmint Oil on DB-1 Resolution Check min (0.18 mm, H 2 Carrier) 10.6 min -9.7 min (0.18 mm, He carrier) 17.7 min (0.25 mm, He Carrier) 27.4 min Page 52 26

27 Resolution Maintained Compounds Sabinene β-pinene α-terpinene p-cymene Speed Gain Compound Resolution 0.25 mm 0.18 mm Helium Helium N/A 35% 0.18 mm Hydrogen % Page 53 Aromatic Solvents on HP-INNOWax Page 54 27

28 Aromatic Solvents on HP-INNOWax 20m x 0.18mm ID x 0.18um 4.6 min min 60m x 0.32mm ID x 0.5um 22.6 min Page 55 Aromatic Solvents on HP-INNOWax Modified Temp then converted to Hydrogen Page 56 28

29 Aromatic Solvents on HP-INNOWax (App. Note EN) 20m x 0.18mm ID x 0.18um Helium 4.6 min min Hydrogen 3 min Page 57 CONCLUSIONS Stationary Phase Chosen for optimized selectivity Length Shorter might be possible without losing a lot of R Carrier Gas Helium can still go fast but Hydrogen has the most advantage at high velocities Flow Ramp Increase at end of run for lonely late eluters Temperature Program Use MTS to scale temps properly Method Translation Software FREE, reliable Diameter Smaller allows shorter length but has less capacity Small Change in ID Easier to Translate Again think capacity Page 58 29

30 TECHNICAL SUPPORT , #4, # (Daron) (toll free) Page 59 For More Detailed Information Fast Analysis if Aromatic Solvent with 0.18 mm ID GC Column" ( EN) Analysis of Semivolatiles Using High Efficiency Capillary GC Columns ( EN) Rapid Analysis of Food and Fragrances Using High-Efficiency Capillary GC Columns ( EN) Agilent J&W High-Efficiency Capillary columns: Productivity- Enhancing Tools for Fast GC Applications ( EN) Page 60 30