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Although glass is widely thought of as an “inert”
material, glass surfaces are, in fact, slightly acidic and
highly adsorptive, due to the presence of silanol
groups (SiOH). These reactive groups interact via
hydrogen bonding with amine (-NH), carboxylic acid
(-COOH), hydroxyl (-OH), or thiol (-SH) functional
groups, and compounds containing these groups
adsorb to untreated glass surfaces. To minimize
adsorption in sample preparation glassware and in
the GC sample pathway, and prevent chromatographic
Siltek™/Sulfinert® Treated Electropolished Stainless Steel Tubing
1/8" OD: 5 ft. to 100 ft. in one continuous coil;
1/4" OD: 5 ft. to 300 ft. in one continuous coil.
Longer lengths will be more than one coil.
Price-per-foot
ID OD cat.# 5-24 ft. 25-99 ft. 100-299 ft. >300 ft.
0.085" 1/8" 22538
0.180" 1/4" 22539
Silcosteel®-CR Treated Electropolished Stainless Steel Tubing
Restek also sets the highest standard in transfer tub-
ing for analytical and process applications. The near-
mirror finish of this electropolished tubing (surface
roughness of only 5-7 micro-inches) creates a very
small surface area that, in combination with
unequalled Restek surface treatments, ensures supe-
rior inertness (Siltek ™) or greatly enhanced corro-
sion resistance (Silcosteel ®-CR). Further, we can
provide continuous coils of 1 /8" tubing up to 100 feet
(30.5m) or 1 /4 " tubing up to 300 feet (91.4m)—a
first for electropolished tubing.
Price-per-foot
ID OD cat.# 5-24 ft. 25-99 ft. 100-299 ft. >300 ft.
0.085" 1/8" 22536
0.180" 1/4" 22537
Siltek™ and Silcosteel®-CR Treated Electropolished Stainless Steel Tubing
✔ Exceptional inertness.
✔ Improved reliability and reproducibility; longer lifetime.
✔ Use with treated fittings for the most inert sample pathway available.
The extremely inert Siltek™ surface is ideal in sulfurs
or automotive exhaust testing, stack gas sampling,
process monitoring, or any other application in
which a representative sample must be transferred
without loss.
In systems used to transfer hydrochloric, nitric, sul-
furic, or other acids, or seawater, Silcosteel ®-CR
treated electropolished stainless steel tubing will last
longer and require less maintenance. Silcosteel ®-CR
treated samples were very well protected from pit-
ting and crevice corrosion, compared to bare steel
samples (Table 1 and Figure 1, p. 10).
For maximum inertness, we recommend a sample
transfer system constructed from Restek treated
electropolished stainless steel tubing and Restek
treated Swagelok ® fittings. To find out how Restek
treated components will improve your system’s per-
formance, contact our Technical Service Group (ext.
4), or your Restek representative, and ask to speak
with our coatings experts.
Dimethyldichlorosilane (DMDCS)
Neat, 20mL/ampul
Each 5-pk.
31840 31840-510
Deactivating Glass Surfaces with
Dimethyldichlorosilane (DMDCS)
by Jack Crissman, Ph.D., Analytical Reference Materials Product Marketing Manager
OH
Si
O
O O
OH
Si
O
O
O
Si
O
O O
O
Me Me
Si
O
O
Si
+HCl
Figure 1 Dimethyldichlorosilane deactivates silanol groups on a glass surface.
DMDCS
An alternative procedure, polymeric deactivation, provides maximum coverage of
glass surfaces and should be used to treat inlet liners for critical analyses involving
very low concentrations of highly active compounds (e.g., endrin, DDT, drugs).
All liners supplied by Restek undergo polymeric deactivation.
For ultimate inertness, and most accurate data for trace levels of reactive analytes,
we recommend Siltek™ deactivation. Siltek™ deactivated guard columns, inlet sleeves,
and other glassware are listed in the Restek catalog. For other items, ask our
Technical Service chemists or your Restek representative about deactivation.
tailing or loss of sensitivity at low sample concentra-
tions, it is important to eliminate or mask the reactive
silanol groups.
One popular way to deactivate glass surfaces is to
chemically bond a non-adsorptive molecule to the
active silanol groups (Figure 1). This typically is
accomplished using dimethyldichlorosilane—
DMDCS. The procedure is suitable for most analyses
that involve concentrated samples and non-active
matrices. It can be followed to clean and deactivate
glass GC inlet liners, derivatization vials, and all
glassware used for preparing analytical reference
materials. Restek now offers DMDCS in 20mL
ampuls, for analysts who wish to deactivate their
glassware themselves.
✔ Convenient 20mL ampuls.
✔ Unopened ampuls have long shelf life.
✔ Detailed deactivation procedure available on request.
Restek
Innovation !
Alternative
Surface
Treatments