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Low-Bleed Column,
New Reference Mixes for
Semivolatile Organic Analytes
in Drinking Water
Using Gas Chromatography/Mass
Spectrometry (EPA Method 525.2)
the
800-356-1688 ★ 814-353-1300
2003 vol.3
Advantage
Innovators of High Resolution
Chromatography Products
in this issue
By Christopher English, Environmental Innovations Chemist & Katia May, Ph.D., R&D Chemist
Rtx®-5Sil MS column provides:
✔ extremely low bleed, for greater sensitivity in GC/MS applications.
✔ excellent resolution of 110 target semivolatile compounds in
EPA Method 525.2.
EPA 525.2 reference materials are:
✔ economical — calibration mixtures at 1000µg/mL concentration, for more
analyses per ampul.
✔ convenient — 106 compounds in only six mixtures.
✔ calibration mixtures formulated by chemical class: semivolatiles, PCB
congeners, organochlorine pesticides, nitrogen/phosphorus pesticides.
✔ six nitrogen/phosphorus pesticides in a separate mix, for stability.
Gas chromatographic analyses for semivolatile ana-
lytes in drinking water require an inert, thermally
stable, low-bleed stationary phase. EPA Method 525,
a liquid-solid extraction / capillary GC/MS analysis, is
applicable for monitoring a wide range of semi-
volatiles in an aqueous matrix. The new revision,
Method 525.2, includes 110 target compounds.
Restek provides the materials needed for this analysis:
extraction disks, reference materials, and an inert
column capable of excellent response for acids and
bases, even at single digit nanogram on-column
quantities.
Of the EPA GC/MS methods for analyz-
ing semivolatiles, Method 525.2 is
the most demanding for column
inertness. Method 525.2 target
analytes include many active
compounds, e.g., endrin,
methoxychlor, DDT, pen-
tachlorophenol. Simple
adjustments to the
injection conditions
can yield great
improvements in
sensitivity, especially for active and high molecular
weight compounds. Analytes can degrade in the
injection port and exhibit excessive tailing. To pre-
vent this, we use a Drilled Uniliner® inlet liner: a
Press-Tight® seal between the fused silica column
and the internal surface of the liner eliminates con-
tact between the sample and the hot metal surfaces
in the injection port. A pulsed injection (30psi, 0.5
min.) reduces the time the analytes spend in the
injection port, and helps to minimize breakdown.
Pulsed pressure injection increases the possibility of
breaking the seal between the column and the liner.
Therefore, head pressure should not exceed 50psi
when using the pulsed splitless mode. A starting
temperature of 35°C helps ensure excellent peak
shapes for early eluting target analytes.
To reduce bleed and activity, Restek continues to
explore new synthesis routes for both column
deactivation and the stationary phase polymer.
Improvements in technology allow our Rtx ®-5Sil MS
columns to withstand high bake-out temperatures
without loss of deactivation. The inset in Figure 1 is
an example of superior efficiency and low bleed for
a mid-point standard, at 330°C. Peak shape and
Low-Bleed GC Column,
New Reference Mixes
for Semivolatile Organics
in Drinking Water
pages 1-3
Verify Fruit Juice Quality
from Organic Acid Profiles,
Using HPLC
pages 4-5
Special-Purpose HPLC Column
for PAHs
page 5
New MegaMix ™ Reference Mixes
for OLC 03.2 Statement of Work
pages 6-7
Semivolatiles Reference Mix for
Wastewater Analysis by GC/MS
pages 8-9
Rtx®-5Sil MS Columns
page 9
Highly Base-Deactivated HPLC
Columns
page 10
Miniature Air Sampling
Cylinders
page 11
New Reference Materials for
Purge and Trap, Environmental,
Forensics Applications
page 11
TO-Can™ Canisters
for Air Sampling
page 12
SilcoCan™ Canisters
for Air Sampling
page 13
Peak Performers
page 14
Cool Tools
page 15
STAR Service
Rewards Program
page 16