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2007.01
Chemical/Petrochemical
Separate Argon fromOxygen Above Ambient Temperatures
Using an Rt-Msieve™ 5A PLOT Column
By Gary Stidsen, GC Columns Product Marketing Manager, and Barry L. Burger, Petroleum Chemist
Rt-Msieve™ 5A Columns (fused silica PLOT)
ID df (µm)
temp. limits
length cat. #
price
0.32mm 30
to 300°C
15-Meter 19720
$395
0.32mm 30
to 300°C
30-Meter 19722
$600
0.53mm 50
to 300°C
15-Meter 19721
$420
0.53mm 50
to 300°C
30-Meter 19723
$580
• Fast, efficient separations at above ambient temperatures.
• High permeability and narrow column diameter mean sharper peaks.
• 100% bonding process eliminates the need for particle traps.
Porous layer open tubular columns—PLOT
columns—offer significant advantages over
packed gas-solid chromatography (GSC) columns.
The open tubular design gives PLOT columns
greater permeability, and their narrow diameter
ensures sharper peaks. The open construction
affords a smaller pressure drop per unit length, so
longer columns can be used. This means much
higher column efficiency and, therefore, superior
resolution. In brief, PLOT columns provide faster
and more sensitive analyses than packed GSC
columns.
Restek PLOT columns are especially effective for
separating mixtures of gaseous analytes. Rt-
Msieve™ 5A PLOT columns contain molecular
sieve 5A particles that are bonded to prevent parti-
cle dislocation, thus protecting valves and detec-
tion systems from damage. They are designed for
fast, efficient separation of argon and oxygen,
hydrogen and helium, and other permanent gases,
including permanent gases admixed in refinery or
natural gas. Finely controlled pore size allows
selective adsorption of specific target compounds,
ensuring that difficult separations can be made
without subambient temperatures.
Figure 1 shows a 30m x 0.53mm ID Rt-Msieve™
5A PLOT column can separate oxygen from argon
to baseline, at above ambient temperature, in
approximately 4 min. Also, the permanent gases
are resolved from methane in the same analysis.
Carbon dioxide does not elute from a molecular
sieve 5A column, but can be chromatographed on
an Rt-QPLOT™ porous polymer column. For
more information, and additional example analy-
ses on Restek PLOT columns, refer to our current
chromatography products catalog or our website.
If your analyses call for difficult separations of
gaseous analytes, and neither conventional packed
GC columns norWCOT capillary columns are pro-
viding the separations you want, or if your analyses
depend on costly or time-consuming conditions, a
Restek PLOT column may be your solution.
Figure 1
Excellent resolution at above ambient temperatures on
an Rt-Msieve™ 5A-PLOT column.
GC_PC00898
Plot Column
Advantages
Gas-liquid chromatography (GLC), the most common mode
of gas chromatography, has limited application in analyses of
gases. Subambient temperatures often are required to
achieve a separation, and cryogenic cooling systems are
costly and inconvenient.
Gas-solid chromatography (GSC), in which gaseous analytes
are adsorbed onto the packing particles, rather than into a
surface coating, is far more effective for separating gases.
Difficult-to-separate small molecules, such as argon and
oxygen, ethane isomers, and many others, can be separated
by GSC at above ambient temperatures.
When analyzing gases, PLOT columns offer significant
advantages over both GLC and GSC packed columns,
including:
•Excellent separations at above ambient temperature;
no costly cooling systems required.
•Sharper peaks, due to smaller tubing internal diameters.
•Higher efficiency and greater sensitivity.
Peak List
1. hydrogen
40ppm
2. argon
30ppm
3. oxygen
50ppm
4. nitrogen
50ppm
5. methane
40ppm
6. carbon monoxide 50ppm
Column:
Rt-Msieve
™
5A PLOT 30m x 0.53mm ID, 50µm (cat.# 19723)
Sample:
permanent gases (ppm)
Inj.:
5µL sample loop, 6-port Valco valve, valve temp.: ambient
Inj. temp.:
200°C
Carrier gas:
helium, constant flow
Linear velocity: 5mL/min.
Oven temp.:
27°C (hold 5 min.) to 100°C @ 10°C/min. (hold 5 min.)
Det.:
Valco helium ionization detector @ 150°C
0
2
4
6
8
10
12
6
5
4
3
2
1
Argon resolved
from oxygen.