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1. 2,4,5,6 tetrachloro-
m
-xylene (IS)
2. -BHC
3. -BHC
4. -BHC
5. -BHC
6. heptachlor
7. aldrin
8. heptachlor epoxide
9. -chlordane
10. -chlordane
11. 4,4' DDE
12. endosulfan I
13. dieldrin
14. endrin
15. 4,4' DDD
16. endosulfan II
17. 4,4' DDT
18. endrin aldehyde
19. methoxychlor
20. endosulfan sulfate
21. endrin ketone
22. decachlorobiphenyl (IS)
Stx
™
-CLPesticides Columns
ID (mm) df (µm)
temp. limits
15-Meter
30-Meter
0.25
0.25
-60 to 310/330°C
0.32
0.50
-60 to 310/330°C
0.53
0.50
-60 to 310/330°C
Stx
™
-CLPesticides2 Columns
ID (mm) df (µm)
temp. limits
15-Meter
30-Meter
0.25
0.20
-60 to 310/330°C
0.32
0.25
-60 to 310/330°C
0.53
0.42
-60 to 310/330°C
Siltek
™
Guard Columns
ID
5-Meter (ea.)
10-Meter (ea.)
0.25mm
0.32mm
0.53mm
Siltek
™
Inlet Liners
For Siltek
™
-deactivation, include the suffix number to the inlet liner catalog number
.
Qty.
Siltek
™
Siltek
™
Siltek
™
w/Siltek
™
Wool
w/Carbofrit
™
each
-214.1, $5 addl. cost
5-pk.
-214.5, $20 addl. cost
25-pk.
-214.25, $90 addl. cost
Injection Port Maintenance
Using Siltek
™
-treated Stx
™
-CLPesticides
columns will improve your chlorinated pes-
ticide analyses, but routine instrument
maintenance will also help. The injection
port is where a majority of analytical prob-
lems occur in the analysis of pesticides.
The main problem is the cleanliness and
inertness of the injection port with which
the sample comes in contact. Endrin break-
down is usually indicative of a chemical
reaction taking place in the injection port.
The breakdown could be caused by impuri-
ties in the carrier gas, active metal sur-
faces, a non-deactivated inlet liner, or septa
particles.
The carrier gas is usually the last trou-
bleshooting area investigated and the hard-
est to eliminate. Endrin may react with a
contaminant being carried into the injection
port by the carrier gas. Having gas scrub-
bers in-line for the carrier gas will help
keep this problem from occurring.
The metal surfaces of the injection port
must be kept clean, including the inlet carri-
er gas line. Periodic rinsing of the carrier
gas lines and cleaning the inside of the
injection port may be necessary if endrin or
4,4'-DDT breakdown increases over short
periods of time or when only analyzing
standards. Rinsing of metal surfaces using
solvents (e.g., methylene chloride, hexane
or acetone), or in some cases silanizing the
injection port, has helped. Also, Restek can
coat your injection port with Sulfinert
™
treatment for better inertness.
Improperly deactivated injection port liners
are the primary cause of endrin breakdown.
The best way to avoid this problem is to
replace the liner with a Siltek
™
-deactivated
liner when performing routine maintenance.
Also, there is a standard procedure for
deactivating liners that includes a process
of cleaning the liners in acid and deactivat-
ing with dichlorodimethylsilane.
Septa particles are another cause of endrin
breakdown. The septa particles will sit on
top of a glass wool plug or at the bottom of
the liner. To help eliminate septum coring,
make sure your syringe needle does not
have burrs. Another approach is to try dif-
ferent septa that features reduced coring,
such as InfraRed
™
septa (see pg. 14), and
to change septa more often.
For more detailed information on chlorinat-
ed pesticide analysis, please request
A Guide to Preparing and Analyzing
Chlorinated Pesticides
(lit. cat.# 59892).
Stx
™
-CLPesticides2
30m, 0.32mm ID, 0.25µm
(cat.# 11444)
Siltek
™
—by Restek
GC_EV00511
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1718
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4
6
8
10
12
14 min.
11540
11544
11541
11543
11545
11542
11443
11440
11445
11441
11444
11442
-216.1
-216.25
-216.5
-213.5
-213.1
-213.25
10036
10026
10038
10028
10037
10027