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by Christopher English, Environmental Innovations Chemist
More Reliable Results From
Semivolatiles Analysis
Using Restek Columns and Standards
✔ Rtx®-5Sil MS columns resolve critical pairs and minimize bleed.
✔ Integral guard column available.
✔ 8270MegaMix™ minimizes mixtures needed, has maximum stability.
✔ Monitor all relevant semivolatiles at one detector sensitivity—8270 MegaMix™
includes 3 and 4 methylphenol at 0.5x concentrations of other components.
Complex mixtures of semivolatile organic compounds
are extracted from water, soil, or solid waste samples,
concentrated, and analyzed by gas chromatography.
The current compound list for US EPA Method
8270D, for example, includes basic, neutral, and
acidic compounds with boiling points from 150°C to
500°C. Other semivolatiles methods are similarly
complex. Because these analyses encompass a broad
range of compound classes and require low detection
limits, and because sample extracts can include non-
target contaminants, significant demand is placed on
the efficiency, inertness, thermal stability, and sample
capacity of the analytical column. These parameters
must be optimized to provide good resolution, fast
analysis times, and high sample throughput. The col-
umn must have adequate sample capacity to handle
the high concentrations of contaminants sometimes
found in these extracts, while exhibiting the high
inertness needed for accurate quantification of target
analytes down to low ng/µL levels.
Restek has designed Rtx®-5Sil MS 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®-5Sil MS columns exhibit excellent inert-
ness and low bleed, even at 330°C. The optimized
stationary phase, proprietary deactivations, and inher-
ently low bleed of the Rtx®-5Sil MS phase, combined
with the integral guard column, overcome the prob-
lems presented by the compounds and conditions
inherent to semivolatiles analysis. High column effi-
ciency ensures the resolution needed to quantify criti-
cal pairs and structural isomers, as shown by the sep-
aration of benzo(b)- and benzo(k)fluoranthene
(peaks 83/84) in Figure 1.
Rtx®-5Sil MS columns are available with an integral,
deactivated 5- or 10-meter Integra-Guard™ guard col-
umn that prevents non-volatile residues from collect-
ing in the analytical column, where they could inter-
fere with 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 8270 MegaMix™ eliminates mixing and mini-
mizes preparation time for calibration and laboratory
control samples—it combines all current target ana-
lytes in EPA Method 8270D. 8270 MegaMix ™ compo-
nents are indicated in bold in the list of analytes in
Figure 1. A unique feature of this mix is the inclusion
of 3-methyl- and 4-methylphenol at 0.5x the concen-
tration of the other components, so you won't have to
adjust reporting limits when analyzing for these com-
pounds. A long shelf life for unopened ampuls of
8270 MegaMix™ minimizes ordering and inventory
problems.
If you are monitoring semivolatile analytes according
to US EPA Method 8270D, or similar methods, trust
Restek Rtx®-5Sil MS columns and 8270 MegaMix ™ to
help you obtain 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.
*For more information about Integra-Guard™ columns,
request lit. cat.# 59441.