• 8 •
800-356-1688
by Christopher English, Environmental Innovations Chemist
MoreReliableResults From
SemivolatilesAnalysis
Using Restek Columns and Standards
✔
Rtx
®
-5Sil MS columns resolve critical pairs andminimize bleed.
✔
Integral guard column available.
✔
8270MegaMix
™
minimizesmixtures needed, hasmaximum stability.
✔
Monitor all relevant semivolatiles at one detector sensitivity—8270MegaMix
™
includes 3 and 4methylphenol at 0.5x concentrations of other components.
Complexmixtures of semivolatile organic compounds
are extracted fromwater, soil, or solidwaste samples,
concentrated, and analyzedby gas chromatography.
The current compound list for USEPAMethod
8270D, for example, includes basic, neutral, and
acidic compoundswithboiling points from150°C to
500°C. Other semivolatilesmethods are similarly
complex. Because these analyses encompass a broad
range of compound classes and require lowdetection
limits, andbecause sample extracts can include non-
target contaminants, significant demand is placedon
the efficiency, inertness, thermal stability, and sample
capacity of the analytical column. These parameters
must be optimized toprovide good resolution, fast
analysis times, andhigh sample throughput. The col-
umnmust have adequate sample capacity tohandle
the high concentrations of contaminants sometimes
found in these extracts, while exhibiting the high
inertness needed for accurate quantificationof target
analytes down to lowng/µL levels.
Restekhas designedRtx
®
-5SilMS capillary columns
to address the demands of semivolatile by GC/MS.
Silarylene polymer technology stiffens the siloxane
chain, preventing its thermal breakdown (column
bleed). The content of this aryl functionality has been
adjusted to give excellent efficiency and lower bleed,
compared to conventional 5%diphenyl/95%dimethyl
phases; Rtx
®
-5SilMS columns exhibit excellent inert-
ness and lowbleed, even at 330°C. The optimized
stationary phase, proprietary deactivations, and inher-
ently lowbleedof theRtx
®
-5SilMS phase, combined
with the integral guard column, overcome the prob-
lems presentedby the compounds and conditions
inherent to semivolatiles analysis. High column effi-
ciency ensures the resolutionneeded toquantify criti-
cal pairs and structural isomers, as shownby the sep-
arationof benzo(b)- and benzo(k)fluoranthene
(peaks 83/84) in Figure 1.
Rtx
®
-5SilMS columns are availablewith an integral,
deactivated5- or 10-meter Integra-Guard
™
guard col-
umn that prevents non-volatile residues from collect-
ing in the analytical column, where they could inter-
ferewith the analytes.Made from a continuous length
of tubing, innovative Integra-Guard
™
columns offer
the column-protecting advantages of a guard column
without the potential for leaks at the interface.*
Our 8270MegaMix
™
eliminatesmixing andmini-
mizes preparation time for calibration and laboratory
control samples—it combines all current target ana-
lytes inEPAMethod8270D. 8270MegaMix
™
compo-
nents are indicated inbold in the list of analytes in
Figure 1. Aunique feature of thismix is the inclusion
of 3-methyl- and4-methylphenol at 0.5x the concen-
trationof the other components, so youwon't have to
adjust reporting limitswhen analyzing for these com-
pounds. A long shelf life for unopened ampuls of
8270MegaMix
™
minimizes ordering and inventory
problems.
If you aremonitoring semivolatile analytes according
toUS EPAMethod8270D, or similarmethods, trust
RestekRtx
®
-5SilMS columns and8270MegaMix
™
to
help youobtain reliable, consistent results.
GC_EV0062
Figure 1
High efficiency Rtx
®
-5Sil MS columns provide the resolution needed to quantify structural
isomers and critical pairs of semivolatiles.
*Formore information about Integra-Guard
™
columns,
request lit. cat.# 59441.
