Permanent gases and CO2 - Fast analysis of permanent gases and CO2 using coupled tandem PLOT columns

Permanent gases and CO

2  

Fast analysis of permanent gases 

and CO

2 using coupled tandem PLOT 

columns

Application Note

Environmental

Authors
Agilent Technologies, Inc.

Introduction
A parallel setup of two PLOT columns is tuned for separation of permanent gases 

in a short time. The sample is injected via a normal injection port and is split into 

the parallel setup of two columns. In this application a short Agilent PoraBOND Q 

is used to separate the CO

2 (and methane) from the permanent gases (first peak 

composite) before the first peak (helium) elutes from the Agilent CP-Molsieve PLOT 

column. After helium, all other permanent gases will be separated which include 

helium, argon, oxygen, xenon, CO and methane. If water is present, it will appear on 

the PoraBond and will elute after the CO

2 peak.

This analysis is done isothermally and requires a long CP-Molsieve column to 

separate peakpairs argon-oxygen and helium-neon. The CO

2 and eventually water 

that enters the Molsieve column will be adsorbed. If the amount of CO

2 or water 

accumulated on the CP-Molsieve causes a shift of the retention time of the inert 

gases out of the integration window, the Agilent Select Permanent Gases/CO

2 and 

water adsorption has very little impact on the retention and many analysis can be 

done before regeneration is required. As methane elutes from both systems the split 

ratio between the columns can be calculated by the ratio of the methane peaks. 

If heavier compounds are present, for instance ethane, ethylene, propane, these 

components will elute later between the peaks that elute from the CP-Molsieve 

column. If such a component interferes with a compound that elutes from the 

Molsieve, the oven temperature must be changed by a few degrees.

www.agilent.com/chem
This information is subject to change without notice.
© Agilent Technologies, Inc. 2011
Printed in the USA
31 October, 2011
First published prior to 11 May, 2010
A02028

Conditions
Technique

: GC

Column

: Agilent Select Permanent Gases/CO

2

Part no. CP7429

Temperature

: 35 °C

Carrier Gas

: Helium, 100 kPa

Injector

: Split 50 mL/min

Detector

: TCD

Sample Size

: 20 μL

Concentration Range : % level

Courtesy

: C. Duvekot, Agilent Application Laboratory, 

Middelburg, The Netherlands

Peak identification
oxygen

nitrogen

methane

carbon monoxide

carbon dioxide