How can Iminimize endrin andDDT breakdown onmy pesticides system?
The major source of analytical problems in pesticide analyses occur in the injection
port—it is important tomaintain the cleanliness and inertness of this area. Two com-
poundsused tocheck injectionport inertnessare4,4'-DDTandendrin. 4,4'-DDTbreak-
down is generally indicative of an injection port contaminated by oily or dirty sample
extracts. Replacing the liner and cuttingoff 6 to12 inches of the guard columnusually
is required to restore system inertness. UseGPC or carbon column cleanup to remove
hydrocarboncontamination.Endrinbreakdown is indicativeof achemical reaction tak-
ing place in the injection port. Endrin breakdown can be caused by impurities in the
carrier gas, activemetal surfaces, an improperly deactivated inlet liner, or septum par-
ticles. Proper and frequent injectionportmaintenancewill helpkeependrinbreakdown
to a minimum. Endrin breakdown also can be significantly reduced by using Siltek
™
guard tubing and inlet liners in the injection port. Siltek
™
deactivation provides the
highest degreeof inertness towardspesticides and typically shows a<1%breakdownof
endrin.
What other analyses can I run on the Rtx
®
-CLPesticides and Rtx
®
-CLPesticides2
columns?
TheRtx
®
-CLPesticides columns also can be used for USEPAMethod 508 pesticides,
8151chlorophenoxyherbicides,619 triazineherbicides,552haloaceticacids, andPCBs
(Aroclors or congeners)which typically are analyzedusing the same instrument as that
used for chlorinated pesticides. The optimized phases of the Rtx
®
-CLPesticides and
Rtx
®
-CLPesticides2 columns allow one column pair and the same instrument for sev-
eral different environmental analyses, thereby increasing theversatilityandusabilityof
your pesticideGC.
What is theproperway tocondition theRtx
®
-CLPesticides columnpair for the lowest
ECD bleed?
Although theRtx
®
-CLPesticides columns are pre-conditioned at Restek, we recommend
re-conditioning thecolumnsbeforeanalyzing samples.ToproperlyconditionanewRtx
®
-
CLPesticidesorRtx
®
-CLPesticides2column, install thecolumn into the injectionport,cap
off the ECD, set the appropriate column flow rate (1.3mL/min. for helium carrier gas),
temperature program the GC from 40°C to 330°C@ 15°C/min., and condition the col-
umns out of thedetector overnight.After conditioning, cool theoven, install the columns
into theECDs and re-condition in thedetectors at 310°C for onehour.
?
At-a-Glance
Product
Information
fromRestek
Rtx
®
-CLPesticidesColumns
ColumnSelection
MadeEasy
3
ezGC
™
software
: Restek has
Retention Index Libraries that
contain more than 3000 com-
pounds analyzed on the most
commonly used stationary
phases, in tendifferent applica-
tion areas including:
• Petroleum hydrocarbons
• Solvents and chemicals
• Flavors and fragrances
• FAMEs
• Pesticides
• PCBs
• Dioxins/Furans
• Semivolatile
• Volatile
• Drugs of abuse
2
Consult theapplicationssection
(over 135pagesof applications
chromatograms) in
Restek’s
Chromatography Products
Catalog
.
1
Contact
Restek’s Technical
Service
at
800-356-1688 or
814-353-1300, ext.4,orcontact
your local Restek representa-
tive. We have over 25 trained
chemistswithdirect laboratory
and applications experience,
ready to assist you in choosing
the best column.
CommonlyAskedQuestions
Rtx
®
-CLPesticides columns simplifypesticide analyses
The introduction of the Rtx
®
-CLPesticides and the Rtx
®
-CLPesticides2 columns has
simplified the choice of phase for pesticide analysis. Both columns achieve baseline
resolution under identical run conditions for the 22 common chlorinated pesticides as
listed in US Environmental ProtectionAgency (EPA) Methods 8081, CLP, and 608,
thus permitting simultaneous dual-column confirmation (Figures 1 and 2). In addition
to their separating ability, the Rtx
®
-CLPesticides columns have amaximum operating
temperature of 330°C and feature low column bleed after conditioning. Also, when
using cyanopropyl-phase or phenyl-phase columns, laboratories typically must cali-
brate using 5-point curves, injectingmixA andmixB compounds separately because
the target compounds coelute. Because no coelution problems occur with the Rtx
®
-
CLPesticides column pair, themixes can be combined. This eliminates the need for at
least five injections during the calibration of the instrument, which may free a mini-
mum of 2.5 hours a day to analyzemore samples.
Although theRtx
®
-CLPesticides columns are available in all three common IDdimen-
sions, Restek recommends the 0.32mm ID column. This column ID provides the best
combinationof sample capacity and efficiency. If your sample extracts are particularly
contaminated, youmay find that the 0.53mm ID columns allow for longer duration of
calibrationbecauseof thehigher capacity. Columns of 0.25mm IDprovidebetter reso-
lution, but have less capacity for contaminated or large samples.
SeeRestek’sChromatography
Products catalog for additional
product information, or visit
.
