Conversion of Agilent EI GC/MSD Systems From Helium To Hydrogen Carrier Gas Bruce D. Quimby, Ph.D. GPD Solutions Group and Harry F. Prest, Ph.D. GC/MS Research and Development October 9, 2012 C&EN Webinar

Question: Have You Ever Tried Converting Your GC/MS From Helium To Hydrogen Carrier Gas? Answer 1: “No. Never thought of trying it. Too busy.” Answer 2: “We did that several years ago. It took some effort, but it has been working fine.” Answer 3: “We tried it once. The results were horrible and confusing! We had a very high background, high noise, and very bad peak shapes. After 4 days, we went back to helium.” C&EN Webinar October 9, 2012

Introduction: Converting from He to H2 Carrier Gas Many GC/MS users are considering changing from helium to hydrogen carrier gas due to price/availability problems with helium. Read Chemical and Engineering News - July 16, 2012 (Page 32-34) This talk describes the steps recommended for converting EI GC/MS methods. It is important to recognize the differences with using hydrogen carrier. Time should be allotted for adapting the method, optimization, and resolving potential problems. Areas that will need attention include: choice of supply of H2 remove/bypass carrier gas filter (may be re-installed later if needed) GC/MSD hardware changes choosing new chromatographic conditions potential reduction in signal-to-noise ratio (2-5x) changes in spectra and abundance ratios for some compounds activity and reactivity with some analytes C&EN Webinar October 9, 2012

Introduction: Converting from He to H2 Carrier Gas Methods that will generally require less optimization include analytes that are: “durable” compounds at higher concentrations analyzed with split injections derivatized Methods that will generally require more optimization include analytes that are: “fragile” compounds at trace concentrations Allow time for necessary updates to SOPs and validation C&EN Webinar October 9, 2012

H2 Safety C&EN Webinar October 9, 2012

Letter from Agilent Safety Engineer: Describes H2 Safety Features of Agilent GCs C&EN Webinar October 9, 2012

Designed for Reliability – H2 Safety Safety Shutdown When gas pressure set points are not met, the valve and heater are shut off to prevent explosion Flow Limiting Frit If valve fails in open position, inlet frit limits the flow Oven ON/OFF Sequence Fan purges the oven before turning on heater to remove any collected H2 Explosion Test GC and MS designed to contain parts in case of explosion C&EN Webinar October 9, 2012

Safety First: Read This Before You Start G3170-90010 C&EN Webinar October 9, 2012

Source of H2 Carrier and Plumbing C&EN Webinar October 9, 2012

Source of Hydrogen: Use a Hydrogen Generator Higher initial expense than cylinders, much lower cost over time Very clean H2, >99.9999% available More consistent purity Safety considerations H2 is only generated at needed pressure (like 40 psig) Flow is limited (like 250 mL/min) Auto-shutdown if set point pressure cannot be maintained Minimal stored gas (like 50 mL at 40 psig) of H2 at any one time Make sure to buy a good one with a low spec for water and oxygen C&EN Webinar October 9, 2012

Hydrogen Generation This is an example of the type of generator to use for H2 carrier gas. Look for generators with a >99.9999% specification and low individual specs on water and oxygen. C&EN Webinar October 9, 2012

Plumbing the Instrument Chromatographic quality stainless steel tubing is often recommended for H2 plumbing and is probably the best choice if available. Users may have to follow local codes or internal company guidelines. We have also used new 1/8th copper that has been cleaned for GC use. Dirty tubing will cause huge contamination problems, as H2 appears to carry dirt out of metal more than He does. Don’t use really old copper tubing, as it becomes brittle and can break. Note that MSD leak checks will not always find big outgoing leaks. Leak check when complete with electronic leak detector. When plumbing a H2 generator, start out with no traps. Only add traps if needed. Make sure the water and oxygen levels are low enough. C&EN Webinar October 9, 2012

Split Vent and Septum Purge Vent Should be Connected to Exhaust C&EN Webinar October 9, 2012

MS Components Required for Conversion: Magnet and Draw Out Lens C&EN Webinar October 9, 2012

Check the Magnet in the 5975 If the magnet in the 5975 does NOT have a serial number along the left edge (as viewed through the source window), it is suitable for use with Helium, but not Hydrogen. If not, please contact your Agilent service engineer to change it to a Helium and Hydrogen compatible magnet before converting the system to H2 carrier. Note: All 5973 magnets are compatible with both He and H2 C&EN Webinar October 9, 2012

Replace the Standard 3 mm Draw Out Lens With the Optional Hydrogen Draw Out Lens Hydrogen Draw Out Plate, Inert Standard 3 mm Draw Out Plate, Inert C&EN Webinar October 9, 2012

Choosing a Column and Method Conditions C&EN Webinar October 9, 2012

MSD Pumping Capacity for H2 is Less than for He MSD Pumping Capacity for H2 is Less than for He This Limits Column Choice These are approximate values for the 5975. Maximum flow of H2 to maintain reasonable source pressure: Performance turbo: 2 mL/min Standard turbo: 1 mL/min Diffusion pump: 0.75 mL/min Pressure pulsing: turbo < 3 mL/min, diffusion < 2.5 mL/min It is very helpful to have an ion gauge on the MS to monitor the vacuum vs. column flow. Try to avoid flows that produce pressures higher than 5 x 10-5 torr. You can get useful data above this pressure, but performance may start to degrade C&EN Webinar October 9, 2012

Guidelines for Choosing Column Dimensions and Flows for Method Converted from He to H2 Determine max flow of H2 into MS that will give source pressure of 5 x 10-5 torr or less source pressure. This is your max column flow. Choose column dimensions at initial oven temp of method to give: a flow < max column flow for vacuum pump a flow > min column flow for efficiency an inlet pressure of at least 5 psig Keeping a temperature ramp of the same number of °C/void time will give similar elution order. Use the Agilent method translator for this. These are only approximate guidelines. Sometimes you may have to deviate from them. C&EN Webinar October 9, 2012

Use 35 cm/sec as minimum for H2 Van Deemter Curves If the flow of He or H2 is too low, you loose efficiency MUCH FASTER than if it is too high. This is why operating at or above minimum linear velocity is important. Use 35 cm/sec as minimum for H2 C&EN Webinar October 9, 2012

Column Choice When in doubt (or a hurry) use: Use 20m x 180 um column and set constant flow at 0.3-0.5 mL/min. Try to get a linear velocity of at least 35 cm/sec Try to use the same phase and phase ratio to get similar elution order. Smaller bore columns have lower capacity. You may have overloading on high level calibration standards, or samples You may need to use pulsed injection to load sample into small bore columns when using a low flow rate. The flow range for your H2 setup is limited on the low side by the flow to get 35 cm/sec and on the high side by the vacuum pump capacity C&EN Webinar October 9, 2012

Using the Agilent Flow Calculator: Set Linear Velocity to 35 for H2 Carrier If Inlet Pressure Too Low, Raise Flow Inlet pressure is too low Set inlet pressure to 5 psig C&EN Webinar October 9, 2012

Using the Agilent Method Translator: 30m x 0. 25 mm id x 0 Using the Agilent Method Translator: 30m x 0.25 mm id x 0.25 um Checkout Column with Perf Turbo Meets flow requirements for pump and column efficiency with 2x speed gain C&EN Webinar October 9, 2012

Using the Agilent Method Translator: With Perf Turbo and Std Turbo For 20m x 0.18 mm id x 0.18 um Column: Meets flow requirements for standard turbo pump. Flow here is chosen to give a 2.5 x speed gain. C&EN Webinar October 9, 2012

Initial Startup with Hydrogen C&EN Webinar October 9, 2012

Initial Problems with Switching GC/MS Methods to from He to H2 Carrier Gas High background that looks like hydrocarbons  Reduced signal to noise (worse MDL)  Significant tailing for many compounds  C&EN Webinar October 9, 2012

Switch to H2 1st Problem: High Background You will see this throughout work with H2. It will get much smaller with time and use. It used to takes days or weeks for background to fall to acceptable levels. Agilent developed a new conditioning protocol to clean-up the background much faster. (see later slide) C&EN Webinar October 9, 2012

GC/MS Toxicology Analyzer Checkout Sample 1 Amphetamine 2 Phentermine 3 Methamphetamine 4 Nicotine 5 Methylenedioxyamphetamine(MDA) 6 Methylenedioxymethamphetamine(MDMA) 7 Methylenedioxyethylamphetamine 8 Meperidine 9 Phencyclidine 10 Methadone 11 Cocaine 12 SKF-525a (RTL Compound) 13 Oxazepam 14 Tetrahydrocannabinol 15 Codeine 18 Lorazepam 16 Diazepam 17 Hydrocodone 19 Oxycodone 20 Temazepam 22 Diacetylmorphine 23 Nitrazepam 24 Clonazepam 25 Alprazolam 26 Verapamil 27 Strychnine 28 Trazodone 21 Flunitrazepam 5 ng/uL each compound 2 4 6 8 10 12 14 16 18 9 17 16 8 10 12 4 11 7 22 3 15 18 2 21 25 27 6 26 14 20 1 19 24 28 23 5 13 C&EN Webinar October 9, 2012

Switch to H2 2nd Problem – Peak Tailing 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 12.00 13.00 200000 400000 600000 800000 1000000 1200000 1400000 1600000 1800000 2000000 Time--> Abundance 20m x 0.18mm id x 0.18 um DB-5MSUI Hydrogen 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 200000 400000 600000 800000 1000000 1200000 1400000 1600000 1800000 2000000 2200000 2400000 2600000 2800000 3000000 Time--> Abundance Helium Immediately after conversion to H2, peak shapes on TIC are poor and tailing badly. C&EN Webinar October 9, 2012

Switch to H2 3rd Problem: Spectrum Changes over Peak Profile There is More Happening Here than Simple Peak Tailing Cocaine 7.20 7.40 7.60 7.80 8.00 8.20 8.40 8.60 8.80 9.00 Peak Spectrum Tail Spectrum 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 2000 4000 6000 8000 10000 12000 14000 m/z--> Abundance Average of 8.048 to 8.085 min.: ToxCKO_H2_4.D\data.ms 91 78 41 64 115 167 128 141 207 191 221 154 281 242 265 341 327 314 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 22000 24000 m/z--> Abundance Average of 8.018 to 8.036 min.: ToxCKO_H2_4.D\data.ms 82 182 42 105 55 68 303 198 122 167 152 272 135 215 244 230 259 341 288 327 Cocaine Not Cocaine C&EN Webinar October 9, 2012

Main Ions of Cocaine Do Not Tail. Tail Made Up of Other Ions Tail is different than peak. May be formed from catalytically shredded main component. This problem is reduced with time Cocaine Tail is not cocaine ions C&EN Webinar October 9, 2012

Considerations for Success H2 Conversion Considerations for Success C&EN Webinar October 9, 2012

Agilent’s Recipe for H2 Success: Minimizing the Time for Chromatography and Background to Stabilize Have a good source of clean hydrogen like a >99.9999% purity hydrogen generator. Keep H2 flow limited to value suitable for your pumping system Use optional Hydrogen draw out lens After setup, purging and pump down: Set the source to max temp for your source (check to see what yours is) Reduce the EMV to 800V Leave the FILAMENT ON overnight. This cleans up background rapidly. Peak shape will be much better and background will be much lower in the morning. Lower the source temp to method value, retune, and run some samples It is a good idea to have an extra set of filaments on hand in case one burns out. This hasn’t been a problem, but a good idea. C&EN Webinar October 9, 2012

Agilent’s Recipe for H2: Success Peak Shape Much Better Background is Lower Better Signal-to-Noise 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 12.00 13.00 14.00 200000 400000 600000 800000 1000000 1200000 1400000 1600000 1800000 2000000 2200000 2400000 2600000 Time--> Abundance C&EN Webinar October 9, 2012

Agilent Toxicology Analyzer Features: Configured, tuned and tested for the application Retention time locked (RTL) with DRS database Constant flow to MS Backflush to reduce cycle time and remove matrix artifact Challenge: Convert from He to H2 carrier without altering performance criteria C&EN Webinar October 9, 2012

He Constant Flow Toxicology Analyzer Parameters: Constant Flow to MS RTL DRS Method Liquid Injector AUX EPC Vent S/S Inlet ~12psi 1m x 0.15 mm id 1.7 mL/min Column PUU 5975C MSD 7890A GC 15 m X 0.25 mm id X 0.25 um DB-5MSUI C&EN Webinar October 9, 2012

H2 Constant Flow Toxicology Analyzer Parameters: Constant Flow to MS RTL DRS Method Liquid Injector No Change in Performance AUX EPC Vent S/S Inlet ~8psi 0.81m x 0.12 mm id 1.7 mL/min Column PUU 5975C MSD 7890A GC 15 m X 0.25 mm id X 0.25 um DB-5MSUI C&EN Webinar October 9, 2012

Converting Toxicology Analyzer from He to H2 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 12.00 13.00 14.00 200000 400000 600000 800000 1000000 1200000 Time--> Abundance Toxicology Check Out Mix Helium Hydrogen C&EN Webinar October 9, 2012

Switching GC/MS Methods to from He to H2 Carrier Gas Reduced high background that looks like hydrocarbons  Improved signal-to-noise relative to pre-conditioned state  Reduced tailing for many compounds  C&EN Webinar October 9, 2012

Performance Expectations C&EN Webinar October 9, 2012

Performance Expectations Signal-to-noise ratio is often worse by about 2-5 x. This obviously varies from compound to compound While most spectra remain same, there are always exceptions. Users should check the reference spectra for important targets to make sure they have not changed Same comment for target/qualifier ratios Some compounds may disappear at low levels. Examples include: some nitrogen and oxygen containing compounds (alcohols, aldehydes, ketones) like those found in flavor samples C&EN Webinar October 9, 2012

Library Match Factors – Helium and Hydrogen Carrier Gas Comparison NIST (Forward) NIST (Reverse) Helium Hydrogen Helium Hydrogen Dichlorvos 924 867 929 904 Mevinphos 925 852 973 967 Ethalfluralin 927 897 927 897 Trifluralin 897 856 897 857 Atrazine 914 901 915 908 BHC-gamma (Lindane, gamma HCH) 925 858 931 878 Chlorpyrifos-methyl 922 897 926 908 Heptachlor 926 851 929 856 Malathion 916 836 953 846 Chlorpyrifos 901 890 902 892 DDE, p,p'- 934 903 946 940 Dieldrin 926 903 927 903 Hexazinone 901 832 906 912 Propargite 851 821 857 829 Leptophos 884 847 884 847 Mirex 903 881 914 934 Fenarimol 905 872 908 877 Coumaphos 864 804 870 813 Etofenprox (Ethofenprox) 906 842 916 843 In general, these 20 spectra in hydrogen carrier show lower match factors than in helium carrier gas. They can still be properly identified in library search. C&EN Webinar October 9, 2012

Lindane Observations Ion ratios changed Extra peaks in H2 Helium Carrier Gas NIST Forward Match = 925 Hydrogen Carrier Gas NIST Forward Match = 858 C&EN Webinar October 9, 2012

Heptachlor Observations Ion ratios changed Helium Carrier Gas NIST Forward Match = 926 Hydrogen Carrier Gas NIST Forward Match = 851 C&EN Webinar October 9, 2012

Other Considerations: H2 is not an inert gas, and therefore inertness problems will still exist or be worse. Use the lowest inlet temp that works (to reduce reactions with H2) Use pulsed injection, especially with small bore columns Consider using an MMI in cold splitless mode for fragile compounds Using a deactivated S/SL weldments might help (but don’t ever scrub it) Avoid using methylene chloride as a solvent (especially wet). At higher inlet temps (like >280C), HCl is formed and causes problems. If must be used, use lowest inlet temp and maybe a deactivated S/SL weldment, or Multimode inlet Avoid carbon disulfide as a solvent Use liners with a taper at bottom to minimize sample contact with gold seal Use Agilent Ultra Inert Liners. C&EN Webinar October 9, 2012

Hydrogen Carrier Summary Get a GOOD hydrogen generator and plumb it properly Pick a column that meets the flow needs of method and MSD pump Do magnet update (if necessary) and install Hydrogen draw out lens After purging and pump down, set source to max temp and EM to 800V. Leave filaments on all night. Reset source temp, retune, and run samples. Run practice samples for a few days to make sure system has stabilized Source cleaning will be needed much less frequently C&EN Webinar October 9, 2012

Thank You for Your Attention For additional information please visit: http://www.agilent.com/chem/heliumupdate C&EN Webinar October 9, 2012