295
GC ACCESSORIES |
GAS PURIFICATION ESSENTIALS
Gas Pur i f icat ion Solut ions
GC
carrier
gas
on/off
valve
moisture
trap
hydrocarbon
trap
high-capacity
indicating
oxygen trap
regulator
Why do I need to use traps and where should I install them?
Carrier gas must contain less than 1 ppm of oxygen, water vapor, or any other trace contaminant, to prevent column degradation,
shortened column lifetime, and increased stationary phase bleed. Contaminants cause ghost peaks to appear during temperature
programming and degrade the validity of analytical data. The expense of using high-purity gases in combination with carrier gas
purifiers will be offset by longer column lifetime and less instrument maintenance.
Moisture Removal
Moisture in carrier gas lines will prematurely degrade oxygen and hydrocarbon traps and increase detector noise (particularly with
ECDs). As a precaution, we highly recommend installing a moisture trap before the hydrocarbon and oxygen traps on all carrier gas
lines. Our favorite trap is the Super-Clean Ultra-High Capacity Moisture Filter (cat.# 22028, pg. 299).
Hydrocarbon Removal
Use a hydrocarbon trap if your gas has a potential source of hydrocarbon contaminants (e.g., an oil pump in an air compressor) or
if you suspect you are observing carrier gas ghost peaks. Install the hydrocarbon trap after the moisture trap, to prevent moisture
from degrading the hydrocarbon-trapping ability of the activated carbon in the hydrocarbon trap. We recommend the Super-Clean
Ultra-High Capacity Hydrocarbon Filter (cat.# 22030, pg. 299).
Oxygen Removal
Oxygen is a column killer and can enter the system at any connection which is leaking. It is present even in ultra high purity gases,
as minute leaks at fittings allow oxygen to influx against the concentration gradient. There are many choices for oxygen removal—
the Super-Clean Ultra-High Capacity Oxygen Filter (cat.# 22029, pg. 299) is popular with Restek chemists. Because oxygen can enter
a gas line at any fitting, the oxygen trap should be the last connection before the gas line enters the chromatograph.
Leak Checking
To prevent column degradation, increase column lifetime, and decrease stationary phase bleed, carrier gas should always contain
<1 ppm oxygen. This can be monitored by continually leak checking all gas system connections using Restek’s Electronic Leak
Detector (cat.# 22839, page 296).
for
more
info
Questions about which carrier gas purifier to use?
Call 800-356-1688 or 814-353-1300, ext. 4, or contact your Restek representative to discuss your application with our technical service chemists.
Restek provides the following total gas system solution:
• Restek gas purifiers provide cost-effective gas purity assurance.
• Restek stainless steel and copper tubing, precleaned and ready to use.
• Swagelok® and Parker A-Lok® tube fittings consistently deliver high-quality performance.
• Extensive line of hand tools to make your work easier and faster, including Restek’s Electronic Leak Detector.
• Gas generators for an uninterupted supply of gas.
• Gas regulators for optimum line pressure control of all your chromatography gases.
Restek’s Technical Service Team (800-356-1688, ext. 4 or
or your Restek representative can answer your ques-
tions and provide system-design advice. From the gas source to your point of use, we offer the products and services that ensure the
purity of your gas.
Use a leak
detector to
check for leaks.
Website :
E-mail :
TelNo : 03 9762 2034 . . . in AUSTRALIA
Mar 2011
