Slide 1: Simplifying GC Syringes and Sample Introduction
Simplifying GC Syringes and Sample Introduction Plunge deep into the world of syringes Mark Sinnott Application Scientist February 27, 2020 1 February 27, 2020 DE.4721759259
Slide 2: Sample Introduction
Sample Introduction Minimal adsorption A complex process dependent on many variables. Speedy Narrow Here are some of the keys to a injection sample band successful injection: No Correct column carryover installation “The Perfect Injection” No Just enough discrimination (clean) sample 2 February 27,
Slide 3: Anatomy of a GC ALS Syringe
Barrel Flange Anatomy of a GC ALS Syringe Needle Termination Plunger Cone tip/PS AS/PS HP Bevel tip/PS 2 Side hole tip/PS 5 (shown) General purpose, excellent Recommended for thin Used in Agilent autosamplers choice for transferring liquids gauged septa and large for optimum performance and from amp
Slide 4: Anatomy of a GC ALS Syringe
Barrel Flange Anatomy of a GC ALS Syringe Needle Termination Plunger Fixed needle syringes (shown) Removable needle syringes • Typically abbreviated FN • Typically abbreviated RN • Needle “cemented” to barrel using epoxy • Allows use of various needle point styles • Cannot be replaced • Threaded con
Slide 5: Anatomy of a GC ALS Syringe
PTFE Barrel Flange Anatomy of a GC ALS Syringe Needle Termination Plunger Standard plungers PTFE-tipped (shown) • Fit tightly within syringe barrel • Limit sample deposit adsorption • Limit loss of volatile sample • Forms gas-tight seal • Individually fitted to the syringe • Replaceable • Not replac
Slide 6: Syringe Selection Tips
Syringe Selection Tips • 10 µL cone-tip, 23/26s tapered needle with PTFE tipped plunger for most SSL and MMI applications • Taper provides strength of larger needle while minimizing puncture size in septum • Ensure proper syringe is configured in software Gold vs. blue syringes • BLUE • GOLD • Speci
Slide 7: Syringe Selection Tips: 5 µL
Syringe Selection Tips: 5 µL 5 µL syringes are ideal for small volume injections BUT: • Typically shorter lifetime (narrow plunger diameter → bends easily) • Do not use in solvent saver mode (too much strain on plunger) • Not available with PTFE tip (plunger sensitive to PTFE friction) – Why not? PT
Slide 8: Micro/Nano Volume Syringes
Micro/Nano Volume Syringes Microvolume syringes Blue line micro/nanovolume syringes are half-marked! Gold Need to configure ALS with 2x syringe volume or risk getting half the response 0.5 µL 1 µL “0.5 µL Syringe” “1.0 µL Syringe” 0.5 µL 1 µL 8 February 27, 2020 DE.4721759259
Slide 9: Need Help?
Need Help? Check out our online syringe selector tool: https://www.agilent.com/search/gn/syringe-selector 9 February 27, 2020 DE.4721759259
Slide 10: ALS Method Parameters
ALS Method Parameters 10 February 27, 2020 DE.4721759259
Slide 11: Injection Volume / Rinse Volume
New GC driver Injection Volume / Rinse Volume Injection volume selection Syringe capacity: • Avoid injection volumes below 10% of syringe capacity Old GC driver – Injection will work, but reproducibility may suffer Injection volume selection • ALS software automatically limits max injection volume t
Slide 12: Starting Points for Injection Volume
Starting Points for Injection Volume Goal: Inject as little sample as possible to meet detection limit • Avoid Back-Flash! – Use vapor volume calculator* • Injection volumes for most organic solvents should be within 1 – 2 µL or less Split ≤ 1 µL – Split vs. splitless • Avoid injecting water- coeffi
Slide 13: Sample Backflash
Sample Backflash* *See recorded webinar on water injections for more info: Negative Effects https://www.agilent.com/en/training- events/eseminars/gc-gc-ms-webinars o Tailing o Carry-over o Peaks splitting/shouldering o Low response Septum purge o Poor reproducibility Carrier gas in H H How To Avoid/
Slide 14: Vapor Volume Calculator
Vapor Volume Calculator 14 February 27, 2020 DE.4721759259
Slide 15: Chromatographic Signs that your Injection Volume is Too High
Chromatographic Signs that your Injection Volume is Too High Overloading • Watch for highly concentrated samples • Keep injection volume small • Overload will result in peak “fronting” or “flagging” • Adjust split ratio as needed • Dilute 1 µL injection 0.5 µL injection Less injection Column overloa
Slide 16: ALS Method Parameters
ALS Method Parameters 16 February 27, 2020 DE.4721759259
Slide 17: Washes and Pumps: Solvents
Washes and Pumps: Solvents • 4 pre- and post washes reduces carryover to one part in 10,000 Analyte solubility at 80% Analyte [Sample] viscosity Number and type of washes Syringe Solvent barrel viscosity wear Wash volume 17 February 27, 2020 DE.4721759259
Slide 18: Wash Vial Volumes
Wash Vial Volumes #𝑝𝑟𝑒 + #𝑝𝑜𝑠𝑡 𝑤𝑎𝑠ℎ𝑒𝑠 # 𝑖𝑛𝑗𝑒𝑐𝑡𝑖𝑜𝑛𝑠 ∗ ∗ 𝑤𝑎𝑠ℎ 𝑣𝑜𝑙𝑢𝑚𝑒 = 𝑤𝑎𝑠ℎ 𝑠𝑜𝑙𝑣𝑒𝑛𝑡 𝑢𝑠𝑒𝑑 𝑖𝑛𝑗𝑒𝑐𝑡𝑖𝑜𝑛 > 2 mL < 2 mL 18 February 27, 2020 DE.4721759259
Slide 19: Washes and Pumps: Solvent Saver
Washes and Pumps: Solvent Saver 10 µL 25 µL High wash application? Try solvent saver. • Steps: – Syringe draws in solvent to specified amount – Syringe and needle rise from solvent bottle – Plunger rises to the 80% mark, rinsing syringe barrel with solvent, then air – Solvent and air discharged into
Slide 20: Washes and Pumps: Solvents
Washes and Pumps: Solvents Frequently clean or replace wash vials • Traces of previous samples will accumulate over time • Do not refill or “top-off” the vial, instead empty, rinse, and replace solvent • Use a cotton swab to remove particulates from the glass surface Contaminated wash vial bottom Co
Slide 21: Washes and Pumps: Solvents
Washes and Pumps: Solvents Choose a wash solvent(s) that make(s) sense for the analysis • Is the analyte soluble in the solvent? • Wash solvent = sample solvent when possible • If using binary wash system make sure the solvents are miscible and rinse with the sample solvent last just before the samp
Slide 22: Miscibility Chart
Miscibility Chart 22 February 27, 2020 DE.4721759259
Slide 23: Washes and Pumps: Diffusion Caps
Washes and Pumps: Diffusion Caps Diffusion caps are important • Reduce volatile solvent diffusion • Better alternative than using vial septa, which will core, contaminate wash solvent vial → septum bleed peaks 5182-0551: 4 mL wash vials with fill markings and caps, 25/pk 07673-40180: Diffusion inser
Slide 24: Use the Right Vial
Use the Right Vial Choose high quality vials and caps • Poorly constructed vial septa → siloxanes → bleed peaks • Low quality vial → leach contaminants into sample • Choose the right cap/septa for your solvent Page 24 February 27, 2020 DE.4721759259
Slide 25: Septum/Solvent Compatibility
Septum/Solvent Compatibility Page 25 February 27, 2020 DE.4721759259
Slide 26: Septum maintenance: TIC of an inlet/vial septum
Septum maintenance: TIC of an inlet/vial septum Common ions for Septa contamination in wash vials or inlet liners can be diagnosed by looking for siloxane polymers in your total ion siloxane chromatogram. Each peak in the chromatogram corresponds to a cyclized (ring structure) siloxane molecule. The
Slide 27: Sample Washes Vs Sample Pumps
Sample Washes Vs Sample Pumps Page 27 February 27, 2020 DE.4721759259
Slide 28: Sample Washes Vs Sample Pumps
Sample Washes Vs Sample Pumps Sample washes • Primes syringe barrel with sample, discards into waste bottle • Improves reproducibility (reduces carry-over) • Be careful of reduced volume samples! Sample pumps • Draws sample into syringe, discards into same vial • Eliminates air bubbles → improves re
Slide 29: Advanced Method Parameters
Advanced Method Parameters 29 February 27, 2020 DE.4721759259
Slide 30: Sample Depth
Sample Depth • Recommend / default (3.6 mm from bottom of vial) • Can change to sample from different heights in the vial - A setpoint of -2 mm will sample 1.6 mm from the vial bottom - Range is -2 mm to 30 mm • Example uses: - Samples with sediment (although properly filtering the sample is ideal)
Slide 31: Plunger Speed
Plunger Speed Fast/variable • Speed setpoints depend on configured syringe size • Fast (Default) • Best starting point for almost all hot S/SL applications – Slower draw ensures efficient sampling, prevents air bubbles – Fast dispense and inject to ensure rapid, complete transfer to inlet Slow • Slo
Slide 32: Viscosity Delay
Viscosity Delay Viscosity delay • Time (sec) plunger pauses between pump and injection • Allows additional time for viscous samples to flow into syringe during pump • Use for viscous solvents like isooctane • Use for highly volatile solvents dichloromethane (to prevent cavitation/bubbles) • A two-se
Slide 33: Injection Types and Automated Sample Preparation (7693)
Injection Types and Automated Sample Preparation (7693) Injection types • Standard • Sandwich injections • Layered injections • Multiple injections Air gap • 0.2 µL default • Helps retain sample in syringe before injection https://www.agilent.com/cs/library/applications/5991-7973EN.pdf 34 February 2
Slide 34: Troubleshooting
Troubleshooting 35 February 27, 2020 DE.4721759259
Slide 35: Troubleshooting
Troubleshooting Problem: No peaks / Reduced Peaks Possible cause(s): • Plugged needle (most common) • Syringe plunger malfunction • Not enough sample • Sample too viscous (V-delay) Suggested action(s): • Clean or replace syringe • Check sample level, use low-volume vial insert • Check sample depth s
Slide 36: Troubleshooting
Troubleshooting Problem: Sample carryover Possible cause(s): • Insufficient number of washes • Solvent wash vial empty • Wrong wash solvent • Dirty ALS needle guide • Dirty septum nut Suggested action(s): • Increase number or type of washes • Rinse with a various polarity solvents • Clean or replace
Slide 37: Troubleshooting
Troubleshooting Problem: Bent Plunger or stuck syringe Possible cause(s): • Typically from sample matrix residuals • Corrosive solvent • Non-matched plunger Suggested action(s): • Clean up samples • Switch to a syringe with PTFE-tipped plunger • Avoid using 5 µL syringes where possible • Clean syrin
Slide 38: Best Practices – Plunger Binding
Best Practices – Plunger Binding • Plunger binding is almost always sample matrix or solvent related (i.e. water or corrosives) • Plungers are perfectly matched to each barrel so it’s a very tight fit (plungers are not interchangeable) – this is true for all non- PTFE syringes • Don’t let the plunge
Slide 39: Troubleshooting
Troubleshooting Problem: Bent needle Possible cause(s): • Improper needle alignment • Narrow gauge needles (26g) bend more easily than larger gauge (23g) needles • Needles more often bend when inserted into sample vial, not the inlet • On-column inlets – wrong needle gauge - Use correct needle suppo
Slide 40: Troubleshooting
Troubleshooting Problem: Poor reproducibility Possible cause(s): • Poor plunger seal • Syringe worn or dirty • Glass walls of syringe are scratched Suggested action(s): • Clean or replace syringe • “Restore” plunger tip (PTFE only!) • Replace plunger (PTFE only!) • Rinse and refill solvent wash vial
Slide 41: Sample Introduction: Important Takeaways
Sample Introduction: Important Takeaways • Successful GC injection is a complex process • Start with a PTFE-tipped 10 µL syringe - Handle the syringe carefully - Avoid pumping plunger when “dry” • Don’t let the wash solvent run low/dry/become contaminated - How long is your sequence? - How is your w
Slide 42: 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/GCMS Columns and Supplies • Option 2 for LC/LCMS Columns and Supplies • Option 3 for Sample Preparation, Filtration and QuEChERS • Option 4 for Spectroscopy Supplies • Option 5 for Standar