26
GCCOLUMNS |
CAPILLARYCOLUMNS
Selecting a GC Column
SelectionofCapillaryColumnSummary
Selecting a capillary column for an analysis canbe done by following these basic steps:
1)Choose theproperphase for thecompoundsbeingchromatographed
a. Review the application sectionof this catalogorwww.restek.com/chromatograms
for similar compound list.
b. Call Restek’s experienced technical support team (800-356-1688, ext. 4)
or e-mail us at:
•
(in theUSA)
•
(international)
• or contact yourRestek representative.
2)Selectcolumn ID, film thickness, and length
a. Base choice on:
• Injection technique (split, splitless, cool on-column, etc.)
• Detector type (is low flow required?)
• Amount of analyte being injectedonto column (sample capacity)
3)Setoptimumparameters foryouranalysis
a. Optimize column flow (mL/min.)
b. Choose appropriate carrier gas (hydrogen, helium, or nitrogen)
c. Optimize oven temperature program
ID
df (µm)
temp. limits
0.25mm 1.40
-40 to 240/260°C
0.32mm 1.80
-40 to 240/260°C
0.45mm 2.55
-40 to 240/260°C
0.53mm 3.00
-40 to 240/260°C
All Restek columns have publishedminimum andmaximum operating temperatures
that establish the working range for the stationary phase. Note that these ranges vary
with the thickness of the coating.
Rtx®-VMS (fusedsilica)
Many phases list 2maximum operating temperatures.
The first temperature is themaximum isothermal
operating temperature.This is the temperature to
which the columns are guaranteed tomeet themini-
mum bleed specification (i.e., lowest bleed level).The
second temperature is themaximum temperature-
programmed operating temperature, the temperature
towhich the column can be heated for short periods
of time (i.e., during a temperature-programmed
analysis). If only one temperature is listed, it is both
the isothermal and themaximum temperature.
Theminimum operating temperature defines the
lowest usable temperature before the stationary
phase solidifies. Operating the column below the
minimum temperaturewill not harm the phase, but
poor peak shape and other chromatography problems
may occur.
WhatAre theOperatingTemperatures forMyColumn?
need
more
help?
• Call 800-356-1688or
814-353-1300, ext. 4,
or your Restek
representative.
• Visit
• Email (U.S.):
Email (outsideU.S.):
Chromatogram
SearchTool
Searchby compoundname, synonym,
CAS#or keyword
Website :
E-mail :
TelNo : 03 9762 2034 . . . inAUSTRALIA
Mar 2011
