SampleExtraction andPreparation
Water Samples
•
Amain difference in sample preparation forGC is that the samples are not
diluted 1:1with reagent water prior tobeing injected, as is the case forHPLC
samples
•
Method 8095 requires solidphase extraction (SPE) disks or cartridges to
extract analytes of interest fromwater samples, such as described inEPA
3535A
2
.
The extraction is performed usingSDB/RPS-type disks or RDX type
cartridges.
Please note thatmethod8095does not use the acetonitrile/salting
out extractionprocedure as described inmethod8330.
•
The use of SPE for explosives extraction requires extra drying time after the
sample is loaded.
Most explosive compounds have lowwater solubility, so the
extra drying time helps their recovery into the acetonitrile elution solvent, and
reduces thewater content in the injected sample.
Safetyconsiderations
prevent explosive extracts fromfurther concentration byKuderna-Danish
concentrators.
The extra drying time, when usingSPE, leads todrier extracts
which reduce the need for recalibration andmaintenancewhen usingwater-
sensitive electron capture detectors.
