environmental
Applications
note
RestekCorporation • (800)356-1688 • (814)353-1300 •
#59562A
environmental
Florisil
®
SPEcleanup fororganochlorinepesticidesandpolychlorinated
biphenylcompounds (PCBs)
Tips for Better Results
• 1g tubeswill give themost consistent results regardlessof
final sample volume.
• Flow rateduring elution shouldbe either dropwiseor gravity
feed (novacuum).Thiswill reduce trichlorophenol break-
through.
This procedure is adapted from the US Environmental
Protection Agency (EPA) Contract Laboratory Program,
Statement of Work for Organic Analyses, Multimedia,
Multi-Concentration, OLM04.0. It is not intended to be a
replacement or substitute for the official procedure.
Please refer directly to the published procedure for
additional information.
Preparing forSampleCleanup
A. Determine the sizeofFlorisil
®
solidphaseextraction
(SPE) tubeneeded for sample cleanup.
If the gas chromatogra-
phy (GC) autosampler canoperate reliablywith1mLof sample
extract, thena500mg tube (cat.#24031&24032) isusedand the
required final volume is1mL. If theGCautosampler requiresa
larger samplevolume, prepare2mLof sampleextract usinga1g
tube (cat.#24034).Manual injection requiresonly1mL final
extract anda500mg tube. See
Tips forBetterResults
below.
B. Every lot ofFlorisil
®
adsorbentmustbequalitycontrol-
tested foractivity level beforeusing for samplecleanup.
Add0.5mLof2,4,5-trichlorophenol solution (0.1µg/mL in
acetone) and0.5mLofStandardMixtureA (midpoint concentra-
tion) to4mLof hexane.Reduce the final volume to0.5mLusing
nitrogen. Placemixtureonto the topof awashedFlorisil
®
cartridge, and elute itwith9mLofhexane:acetone (90:10) v/v.
Use twoadditional 1mLhexane rinses toensurequantitative
transferof standard from theFlorisil
®
tube.Reduce the final
volume to1mLusingnitrogen, andanalyze the solutionby
GC/electron capture detector (ECD) using at least oneof theGC
columnsspecified for sampleanalysis.Determine the recoveryand
percent recovery for eachanalyte.Thecheck samplemust be
analyzedonaGC/ECDandmeet the initial calibrationand
calibrationverification technicalacceptancecriteria.TheFlorisil
®
lot isacceptable if all pesticidesare recoveredat 80% to120%, if
the recoveryof2,4,5-trichlorophenol is less than5%, and ifno
peaks interferingwith the target analytesaredetected.
Procedure forSampleCleanupUsingFlorisil
®
SPETubes
1. Attach thevacuummanifold (cat.#26077or 26080) toa
vacuumpump, install a trapbetween themanifoldand the
vacuum source.Adjust thevacuumpressure in themanifold to
<20"Hg. PlaceoneFlorisil
®
tubeonto thevacuummanifold
foreachsampleextract.
2. Prior tocleanupof samples, the tubesmust bewashedwith
hexane:acetone (90:10).This isaccomplishedbyplacing the
tubeon thevacuummanifold, pullingavacuum, andpassingat
least 5mLof thehexane:acetone solution through the tube.
While the tubesarebeingwashed, adjust thevacuumapplied to
each tube so that the flow rate througheachcartridge is
approximatelyequal.Donot allow thecartridges todryafter
they have beenwashed.
3. After the tubeson themanifoldarewashed, release the
vacuumandplacea rackcontaining labeled10mLcollection
vessels inside themanifold.
4. After thecollectionvesselsare inplace, restore thevacuum to
themanifold. Transfer avolumeof extract equal to the required
final volume (1or2mL)* fromeach sample, blankormatrix
spike to the top frit of theappropriateFlorisil
®
tube.Usea
syringeorvolumetricpipette to transfer theextract to the
cleanup tube.
5. Elute thepesticidesandPCBs in theextract concentrates
through thecolumnwith8mLof hexane:acetone (90:10) and
collect into the10mLcollectionvessels that areheld in the
vacuummanifold rack.
6. Transfer theelute ineachcollectionvessel toaclean, appropri-
atevessel for nitrogenblowdown. Perform twoadditional 1mL
hexane rinses toensurequantitative transferof the tubeelute.
7. Adjust theextract to the final volume (1or2mL)byusing
either nitrogenblowdownor amicroSnyder column.Measure
the final volumewitha syringeorby transferring theextract to
avolumetric flask.Theextract is ready forGC/ECDanalysis.
*This volumemust equal the final volume after Florisil
®
cleanup.
