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• 23 • 2008 vol. 3
Editorial
separation (and another disappointed user is born!). Please also bear in mind
that the above options will reduce all baseline segments in your chro-
matogram to the same extent. So, if you have over-resolution throughout your
chromatogram except for one critical peak pair that is just barely resolved, for-
get about these options. In general however, all of the above options are low-
risk options that could be tried before moving on to the more elaborate steps
discussed below.
Now that you have eliminated all the empty parts of the baseline you can
move to step 2, maximizing the selectivity of the system. Selectivity is the abil-
ity to distinguish between compounds. This can be done through the separa-
tion or through detection (once the method for sample preparation has been
selected). Options for improving selectivity include:
• using a more selective stationary phase or coupled columns.
• using conventional 2-dimensional or comprehensive 2-dimensional GC.
• using selective detection, with mass spectrometry (MS) being
particularly attractive.
• backflushing.
Because the above options are all rather expensive and require special instru-
ments and expertise, the only really widely used option is the use of MS detec-
tion. Indeed MS is a marvellous way to get selectivity in an easy and quick way.
You have now gone through the two initial steps of speeding up your method.
You have selected a system that offers you the required resolution, yet not
more resolution than really needed. If the analysis time in this "minimum
acceptable resolution" situation still exceeds the desired or permitted time,
options that reduce the analysis time at constant resolution should be exploit-
ed. Possibilities include:
• reducing the column inner diameter.
• using hydrogen as the carrier gas.
• appling vacuum-outlet conditions.
• using turbulent flow conditions.
Of these options the first two always work; however, vacuum operation only
works if you have a separation on a short wide-bore column, and turbulent
flow operation in practice is of little use.
Mea culpa, with more than 20 papers published on fast GC, I have also con-
tributed to the chaos in faster GC. I hope the above discussion helps resolve at
least part of the confusion. Faster GC is possible, it is always possible, and the
need for it is actually still increasing as a result of recent trends in process con-
trol and high-throughput experimenting.
1. P. Korytár, H.-G. Janssen, E. Matisová, . Brinkman, Trends in Analytical Chemistry 21 (2002) 558-572.
Achieving Faster GC
Continued from page 2
Tradeshow Schedule
October, 2008
Show: 2008 NIH Research Festival Exhibit
Date: Oct. 16-17
Location: National Institutes of Health, Bethesda, MD
Show: Society of Forensic Toxicologists (SOFT)
Date: Oct. 27-31
Location: Arizona Grand Hotel, Phoenix, AZ
Show: COLACRO XII
Date: Oct. 28-30
Location: Florianopolis Convention Center, Florianopolis, Brazi
November, 2008
Show: 2008 AAPS Annual Meeting & Expo
Date: Nov. 16-20
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Show: Eastern Analytical Symposium (EAS)
Date: Nov. 17-20
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Show: Symposium on Air Quality Methods & Technolog
Date: Nov. 3-6
Location: Chapel Hill, NC
Show: LC/MS Montreux Symposium
Date: Nov. 12-14
Location: Montreux Convention Center, Montreux, Switzerlan
January, 2009
Show: Gulf Coast Conference
Date: Jan. 20-21
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Seminar Schedule
Date Cat. # City State
Petrochemical Seminar
10/27 65746 Corpus Christi TX
10/29 65747 Houston TX
10/31 65748 Oklahoma City OK
Comprehensive HPLC
11/3 65749 Seattle WA
11/5 65750 San Francisco CA
11/7 65751 San Jose CA
Restek On-the-Road
Hans-Gerd Janssen received his Ph.D. in analytical chemistry from
Eindhoven University in 1991. After having worked at Eindhoven as an
associate professor for eight years, he joined Unilever Research to work
as the group leader for chromatography and mass spectrometry. In 2004,
Hans-Gerd was appointed part-time professor at the University of
Amsterdam, focusing on biomacromolecular separations. Catch the Buzz
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