consider using alternative carrier gases
TRANSCRIPT
Lee Marotta, Mike Baylerian, Alan Gallaspy, Andy Tipler, Miles Snow
When your GC/MS is out of
Breath
Helium and the use of alternative GC
carrier gases
Page 2
Outline
Some background to Helium: where it comes from, who uses it, how
much it costs and why we should be concerned about consuming it.
How to reduce wastage of Helium on a GC: method optimization and
elimination of leaks.
Using alternative carrier gases. Benefits and trade-offs. Compatibility
with detectors, especially MS.
Conclusion and questions.
Background
Page 4
Element Abundance (%)
Hydrogen 73.90
Helium 24.00
Oxygen 1.07
Carbon 0.46
Neon 0.13
Iron 0.11
Nitrogen 0.10
Silicon 0.07
Magnesium 0.06
Sulfur 004
Others 0.07
A1689-zD1
Space (or to give it a more technical
name, 'The Universe') is big. Really Big.
Douglas Adams, The Hitchhiker’s Guide to the Universe
Page 5
Helium is constantly being formed in
stars by thermonuclear fusion of
hydrogen at ~15,000,000K
Page 6
Gas Abundance (%)
Nitrogen 78.08
Oxygen 20.95
Argon 0.93
Carbon Dioxide 0.04
Neon 0.0018
Helium 0.00052
Methane 0.00017
Krypton 0.00011
Hydrogen 0.000055
Water ~ 1
NASA
The Earth:
Mostly Harmless: a small, blue-green
world in one of the less fashionable
sectors of the galaxy.
Douglas Adams, The Hitchhiker’s Guide to the Universe
Page 7
Helium is able to Escape the Confines of Gravity
Helium
goes this
way
Page 8
Helium Formation on Earth
Produced by the radioactive decay of isotopes of uranium and
thorium
This is a very slow reaction
Current natural reserves have been generated over the last 4.5
billion years!
The earth’s crust contains 0.0008% helium
Some natural gas contains up to 7% helium
Page 9
Helium Mining
USA (83%)
Algeria (11%)
Canada
Poland
Russia
Qatar
Amarillo, Texas
Page 10
Applications of Helium
Application Usage
(%)
Lifting 15.1
Magnetic Resonance Imaging (MRI) 15.0
Welding 14.9
Chromatography 7.6
Heat Transfer 6.4
Leak Detection 5.6
Pressurizing 5.5
Fibre Optics 4.1
Diving Mixtures 4.0
Superconductors 2.9
Inert Atmospheres 2.7
Nuclear Magnetic Resonance (NMR) 1.3
Other 14.9
Page 11
The Price of Helium in the USA
United States Bulk Helium Cost vs. Year
0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
1930 1940 1950 1960 1970 1980 1990 2000 2010
Year
Pri
ce p
er
Metr
ic T
on
(U
.S. $)
Price no longer
controlled by US
government
Price of Helium dramatically
Increasing every year
Source: U.S. Geological Survey
Page 12
One Man’s View - Helium will be Exhausted in 8 Years!
"The government had the good vision to store helium, and the question now is:
Will industry have the vision to capture it when extracting natural gas, and
consumers the wisdom to capture and recycle? This takes long-term vision
because present market forces are not sufficient to compel prudent practice.
When they stick that straw into the ground to suck out oil and gas, the helium
comes out, and if it doesn't get captured it drifts into the atmosphere and is lost.
Helium production is a side industry to oil and natural gas, an endeavor that
nobody wants to lose money on."
Lee Sobotka, Ph.D., professor of chemistry and physics in Arts & Sciences
at Washington University in St. Louis, December 2007
Government not funding the mining of Helium leaving it to industry
A lot of helium is not capture during drilling for oil, etc.
Page 13
Helium Balloons
Balloon retailers, which use about 7 percent of the (USA)
national supply, are already promoting conservation.
The International Balloon Association, a Wichita, Kan.-
based group of balloon manufacturers and distributors, is
asking its members to consider alternatives to helium, such
as good, old-fashioned air, particularly for balloons that don't
have to float. It's also promoting products that can extend
the float time of a balloon and decrease helium use by
about 25 percent.
Helium drifting away
St.Louis Post, January 2008
Page 14
Helium in Gas Chromatography
Despite conflicting opinions and statistics, there is growing
concern about the availability and cost of helium
Chromatography consumes 7.6% of the world’s helium supply
As chromatographers, we can make a significant impact on the
total amount of helium consumed by:
• Eliminating wastage
• Using alternative gases such as hydrogen and nitrogen
As instrument vendors we can design and provide tools and
techniques to assist users in this enterprise
Saving Helium
Page 16
Causes of Helium Waste
Deliberate (e.g. from injector split settings in GC method)
Non-Deliberate (e.g. from leaks)
Both of which can be easily addressed by the user
Page 17
What Lifetime is Expected from a Standard 8000L Cylinder?
Mode Column
Flow Rate,
mL/min
Split flow
Rate,
mL/min
Septum
Purge Flow
Rate,
mL/min
Estimated
Cylinder Lifetime
with 1 GC, days
On-column
capillary (POC)
2 - - 2771
On-Column
Capillary (PSS)
2 10* 3 369
Packed column 20 - - 277
Packed Column 50 - - 111
Splitless injection 2 25** 3 180
Split injection 2 25 3 185
Split injection 2 50 3 101
Split injection 2 100 3 53
Split injection 2 200 3 27
Split injection 2 500 3 11
* A small split flow is recommended to help keep the injector swept and clean
** The split vent is closed during injection so total usage is slightly reduced
Page 18
Cost of a Cylinder Containing 8000L 5N-Grade Helium
Country Example Cost (€)
USA 35
Taiwan 117
Germany 146
France 150
Italy 160
China 299
Brazil 507
Page 19
The PerkinElmer Clarus Gas Chromatographs with PPC Pneumatics
Clarus 500
Clarus 600
All these have support for
automated leak limitation
and detection
Page 20
Conserve Helium by Turning Down the Split Flow Whenever Possible!
Use a simple timed event on the Clarus 500 or 600 GCs to reduce the split flow rate after the injection is complete
For a lab of 5 GCs running with 200mL/min split flows, this single action, that takes just a moment to enter, will:
• Save up to €10,000/year in helium costs
• Eliminate up to 60 cylinder exchanges/year
• Contribute significantly to helium conservation
Page 21
Sources of Leaks
Tank regulator
Laboratory plumbing
Connections to the GC
Internal plumbing in the GC
Injector septa and o-rings
Column ferrules
Column breakage
Page 22
Buy a Helium Sniffer – it will Save You Thousands of Euros!
Never use soap solution to locate leaks!
Clarus GC PPC Split Pneumatics – Split Mode
Solenoid
Valve
Flow Sensor
Pressure
Sensor
Proportional
Valve Proportional
Valve
Injector
Column
Controller
Controller
• Leaks are detected by a sudden loss in pressure and the system is subsequently shutdown
after 2 minutes
• An automatic system leak-check may be performed at the start of each run – again the system
is shutdown after 2 minutes if a fault is detected
• In split mode, the PPC controller regulates the gas-flow into the injector so leakage will never
exceed this rate.
Page 24
PPC Split Pneumatics – Splitless and Leak-Check Mode
Solenoid
Valve
Flow Sensor
Pressure
Sensor
Proportional
Valve
Injector
Column
Controller
Monitored Output
Page 25
Automatic Leak Checking with PPC
Flow rate into injector
checked as a pre-run event
If flow rate exceeds limit,
GC will shutdown
Prevents major loss of
carrier gas
Also reduces explosion risk
with hydrogen carrier gas
Page 26
Summary of Options to Reduce Helium Wastage
Reduce or eliminate split flows when not needed
Detect and eliminate leaks
Page 27
A Proposed Charter for Chromatographers
Chromatographers
• Know how much helium you use (your Helium Footprint)
• Use instrument features to reduce splitting when it Is not
necessary
• Be mindful about detecting and eliminating leaks
• Consider using alternative carrier gases
Vendors
• Provide tools for reducing and tracking helium usage
• Optimize injectors and detectors for use with other carrier gases
• Develop example applications and proof statements with other
carrier gases
• Encourage end users to reduce helium usage
Using Alternative Carrier
Gases
Page 29
Content
Review of available gases
Advantages and tradeoffs
Compatibility with injectors, columns and detectors
Mitigating the risks in using hydrogen
Effect on performance
Special considerations for MS
Options for ATD and HS
Review of Carrier Gases
Gas Helium Hydrogen Nitrogen Cost Expensive Low cost Low cost
Speed of
chromatography
Medium Fast Slow
Chromatographic
efficiency
Low Medium High
Flow permeability Low High Low
Supply Pressurized
tank
Pressurized tank or
electrolytic hydrogen
generator
Pressurized tank
or nitrogen
generator Safety concerns Highly explosive
Hydrogen cylinders
Pros
Can keep up with substantial demand if necessary
Can usually get spare cylinder quickly
Cons
Safety concerns with flammability especially with large leaks or catastrophic failures
Inconvenient (and can be dangerous) to move and exchange
Hydrogen generator
Pros
No heavy high pressure cylinders to lug around
Low internal volumes at low pressure means small hazard potential
Intelligent shutdown in the event of a fault
Cons
High initial cost
May not have spare generator on hand for backup
Need to assess demand accurately
Injector and Column Compatibility
Injector Considerations
• Hydrogen – Very low viscosity requires low inlet pressure.
– Potential problems with short (30 m or less), wide bore columns (530
μm).
– MS further limits column dimensions
– Potential Problems with splitless and pressure pulse injections.
• Nitrogen - Optimal linear velocity requires low inlet pressure.
– Potential problems with short (30 m or less), wide bore columns (530
μm).
– MS further limits column dimensions
– Potential Problems with splitless and pressure pulse injections.
Injection Method Considerations with MS
Detector Compatibility
Combustion Detectors (i.e. FID, FPD)
• Constant flow mode is preferable
• Baseline may change in constant pressure or velocity type
operation.
• Remember to combine carrier flow for total hydrogen for
combustion
NPD
• Requires constant flow of hydrogen at ~1 mL/min
• Hydrogen is not a good choice for a carrier gas
Single Quad MS
• Hydrogen potential reduces sensitivity by 2x
• High vacuum column outlet may constrain injector pressure
settings
MS System Performance
GC Sample Handling Devices
Hydrogen is not an acceptable carrier gas for thermal
desorption type sample introduction.
Hydrogen is not an acceptable carrier gas for pyrolysis sample
introduction, since a heated wire glows red hot in the injector.
Hydrogen is an acceptable carrier gas for headspace sample
introduction when using appropriate safety measures
(including a special hydrogen needle).
Detailed Hydrocarbon Analysis using Helium and Hydrogen
70 Minutes
160+ Minutes
Helium
Hydrogen
More
Available
Time
Column Efficiency
Column efficiency
(hence peak shape
and resolution) is very
similar in this region
for all three gases
Clarus GC PPC Systems Support Velocity Control and Display
Capillary column carrier
gas may be controlled by
setting the pressure, flow
or velocity.
In each mode of control,
the current values of all
three are displayed in real
time
Method migration with carrier gas velocity control
5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0
Helium
Hydrogen
Nitrogen
30cm/s at 20°C/min
Same separation with the
same method with all
three gases!
Can I migrate methods with flow or pressure carrier gas control?
7.0 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5 13.0 13.5 14.0 14.5 15.0 15.5 16.0 16.5 17.0 17.5 18.0 18.5 19.0 19.5 20.0 20.5 21.0 21.5
Helium
Hydrogen
Nitrogen
Constant Pressure at
10°C/min with Initial
Velocity of 30cm/s
Same separation if the
initial velocity is the
same!
Clarus GC PPC Split Pneumatics – Split Mode
Solenoid
Valve
Flow Sensor
Pressure
Sensor
Proportional
Valve Proportional
Valve
Injector
Column
Controller
Controller
• Leaks are detected by a sudden loss in pressure and the system is subsequently shutdown
after 2 minutes
• An automatic system leak-check may be performed at the start of each run – again the system
is shutdown after 2 minutes if a fault is detected
• In split mode, the PPC controller regulates the gas-flow into the injector so leakage will never
exceed this rate.
Automatic Leak Checking with PPC
Flow rate into injector
checked as a pre-run event
If flow rate exceeds limit,
GC will shutdown
Prevents major loss of
carrier gas
Also reduces explosion risk
with hydrogen carrier gas
Ensure systems are leak free (and re-check them periodically)
Use an in-line snubber if you are using high pressure cylinders
Use a hydrogen generator rather than a high pressure cylinder
Route gas vents away from the instrument
Use PPC pneumatic systems to limit and detect leakage and to shutdown the system if necessary
Install capillary columns so that they don’t rub against other surfaces
Things the user can do to minimize risks in using hydrogen
Special considerations for GC/MS
Use caution when venting
• Shut down carrier gas before MS pumps
Use extra caution after a power failure or unexpected failure of
vacuum system
• Shut down carrier flow
• Do not turn MS system on immediately
• Allow hydrogen to dissipate
• Use a nitrogen purge accessory
Page 46
GC/MS Drinking Water Tuning
Helium Hydrogen
Mass 525.1 525.2 525.3
DFTPP
Helium
DFTPP
Hydrogen
51 10-80% of base peak 10-80% of base peak n/a 46.6 43.9
68 <2% of 69 <2% of 69 <2% of 69 1.3 1.6
69 n/a n/a present 52.0 45.6
70 <2% of 69 <2% of 69 <2% of 69 0.1 0.5
127 10-80% of base peak 10-80% of base peak n/a 56.6 47.1
197 <2% of 198 <2% of 198 <2% of 198 0.2 0.7
198 base peak or >50% of 442 base peak or >50% of 442 present 100.0 100.0
199 5-9% of 198 5-9% of 198 5-9% of 198 5.4 6.3
275 10-60% of base peak 10-60% of base peak n/a 23.2 24.3
365 >1% of base peak >1% of base peak >1% of base peak 1.9 2.5
441 Present and < 443 Present and < 443 <150% of 443 79.5 78.8
442 base peak or >50% of 198 base peak or >50% of 198 present 64.7 75.3
443 15-24% of 442 15-24% of 442 15-24% of 442 19.7 17.7
Summary
There is a compelling need to switch GC methods away from using helium • Cost
• Sustained supply
• Free up helium supplies for ‘more important’ purposes (e.g. MRI)
There are feasible alternative carrier gases • Hydrogen
• Nitrogen
Chromatography equivalent to that obtained with helium carrier is possible with hydrogen or nitrogen on GC systems that control and monitor gas velocity through the GC column.
Although there is risk of an explosion when using hydrogen, this will be very small if the following are followed: • Hydrogen generator
• Use PPC pneumatic controllers
• Ensure that systems are leak-free
• Route split vents etc. to the instrument exterior
• Use a hydrogen sensor in the GC oven
Thank you!!!!!