Advances in Capillary Column Backflushing Matthew S. Klee, Ph.D. ISCCE 2010 1
Capillary Flow Technology Traits Ease of use - ruggedness Inertness Usability to > 350 oc Excellent exclusion of air No unpurged volumes No porous materials into which compounds can dissolve ( peak tailing) Fast thermal response No outgassing or shedding of particles ISCCE 2010 2
FS Tubing Connections The Magic Unique design provides rugged, reliable connections with minimal unswept volume and high inertness Restrictor 1 out to vent Column 1 In Restrictor 2 or Column 2 Nut Ferrule Channel Plate ISCCE 2010 3
Ferrule Sealing Square cut is not critical Seal region ISCCE 2010 4
Backflush Setup 1. Start with working method and reference sample/chromatogram 2. Extract pertinent method information from current method 3. Select BF configuration 4. Prepare hardware (next slide) 5. Install columns 6. Determine pressure/flow settings, download and test stability 7. Screen standard on new configuration 8. Lock with migrated RTL calibration if RTL method 9. Pick last peak of interest using graphical tool, from which BF timing and conditions are recommended 10. Verify BF works 11. Fine tune BF conditions if necessary ISCCE 2010 5
Preparing hardware during setup Assemble necessary HW & SW (e.g. PCM/EPC, CFT, Instrument Utilities SW) Install any needed modules and accessory kits Check frit (recommend open/zero frit) Check/update PIDs (using instrument utilities SW) Zero all used pressure control zones (inlet, EPC) Decide if you need a split purge and install preferred version ISCCE 2010 6
EPC/PCM instability at low P or flow EPC and PCM modules were designed for most accurate and precise control at flows > 1 ml/min Proportioning valve duty cycle should never be 0% Symptoms are: long stabilization time, cycling P Some backflush configurations require flows of < 1 ml/min Adding a bleed ensures stable pressure control Fixed bleed Variable bleed ISCCE 2010 7
Basic Bleed Configuration He supply IN EPC1 P 2 vent 1/16 Swagelok tee restrictor Oven Purged Union Column 1 Column 2 Det ISCCE 2010 8
Purged 1/16 Union For purged splitting, in-oven connections Eliminates air infiltration and stagnant lines Provides bleed path for EPC stabilization and dumping excess column flow ISCCE 2010 9
Fixed restrictor configuration using G2855-80582 This is inside oven, replacing old Swagelok union These are outside oven on top Big one goes to Aux EPC Use 1/16 straight Swagelok union with Vespel ferrules Small one goes to vent (room, vacuum vent, split vent trap, etc.) Let hang loose or vent using whatever connectors necessary according to user requirements ISCCE 2010 10
Cut off and remake the QuickSwap in-oven fitting, with tubing extending fully into union (past the purge point) ISCCE 2010 11
Fixed split with purged tube fitting vent Aux EPC Outside oven Inlet EPC P 1 P 2 Use Vespel ferrules here Purged Tube Fitting S/S Inlet Restrictor MSD Column CFT Inside Oven ISCCE 2010 12
Variable split bleed saves the day Provides necessary bleed to allow pressure control solenoids to operate well (> 1 ml/min) Maintains low flow even during high-pressure backflush Uses normally unused pressure channel (EPC, Backpressure channel on PCM) Allows split flow to be turned OFF for leak checking Provides the opportunity to program bleed flow for custom applications ISCCE 2010 13
Using 2nd EPC for Bleed During Run Set P 3 < P 2 He supply IN EPC1 P 2 SV Trap IN EPC2 P 3 1/16 Swagelok tee Oven atmosphere 2 ml/min independent of P 2 Purged Union Column 1 Column 2 Det ISCCE 2010 14
Bleed OFF During Leak Check He supply IN EPC1 P 2 SV Trap IN EPC2 OFF 0 ml/min Oven Purged Union Column 1 Column 2 Det ISCCE 2010 15
Variable restrictor configuration using G2855-80581 This is inside oven, replacing old Swagelok union These are outside oven on top From Aux EPC 1 (purge feed line) Use 1/16 straight Swagelok union with Vespel ferrules Vent to split vent trap then to input of EPC 2 ISCCE 2010 16
Post-Column BF with Variable Split Inlet EPC P 3 trap Aux EPC 2 vent P 2 Aux EPC 1 Outside oven Use Vespel ferrules here P 1 Purged Tube Fitting S/S Inlet Restrictor MSD Column QuickSwap Inside oven ISCCE 2010 17
Large-Volume Injection, Cool On- Column Solvent Vapor Exit Not for the novice! ISCCE 2010 18
LVI COC SVE with Pre-Column Backflush to Vent 1 Vent Vent G3186B Purged Ultimate Union G3180B Purged 2-Way Splitter COC Det Uncoated Pre-Columns Coated EPC Column ISCCE 2010 19
LVI COC SVE with Backflush of the column to Vent 2 G3182B Purged Ultimate Union G3186, G1472A G3180A Purged Splitter Ultimate Union Det 1 COC Det 2 Retention Gap Pre Column Column EPC makeup Vent ISCCE 2010 20
Conclusion Capillary column backflushing has a large potential return but requires some attention to detail to set up Cost to implement backflushing is relatively low and is greatly facilitated by readily available instrument parts and accessories ISCCE 2010 21