Waters Certified Sep-Pak - Manual (Page 2)

[ Care and Use ManUal ]
Certified Sep-Pak Cartridges 2
II. UsInG CeRtIFIeD seP-PAK CARt RIDGes
Below is a five step guideline for using Certified Sep-Pak cartridges.
Each separation is different and not all steps may be required for
your application.
1. Prepare sample: The sample can be applied to the Certified Sep-Pak
cartridge in either liquid or a gas phase. If the sample is a solid, it must
be dissolved or extracted prior to loading.
2. Condition/equilibrate cartridge: A conditioning step is required for
reversed-phase sorbents (e.g., C
18
). Use a strong solvent to wet the
stationary phase. Conditioning is followed by an equilibration step
using a weak solvent.
3. Load sample: The sample is loaded onto the cartridge.
4. Wash: The wash step removes interferences while retaining the analyte.
If weakly retained interferences are present in the sample matrix, wash
with an appropriate weak solvent.
5. Elute: Use an appropriate stronger solvent to elute the analyte while
retaining more strongly bound interferences.
III. st RAteGIes FoR soLID-PHAse eXt RACtIon
Purification: Use as a “chemical filter” to retain the component
of interest while interferences elute, or to retain the interferences
while the analyte passes through unretained.
Trace enrichment or concentration: Use to concentrate an analyte
from a dilute solution. This is done when the analyte concentration is
below the detection limit of the analytical method.
Fractionation: Use with a step gradient of increasing solvent
strength to selectivity elute and isolate analytes based on differences
in polarity.
Solvent exchange: Use to adsorb the analyte and elute with a desir-
able solvent. This is helpful of the sample is dissolved in a solvent
that is incompatible with the analytical method.
a. Retention-Cleanup-Elution Strategy
As the sample is loaded onto the cartridge, the analytes of interest are
retained by the sorbent. If needed, an optimized series of washes are
used to remove matrix interference from the cartridge. A strong solvent
is used to elute the analytes from the cartridge. Sample enrichment
results when the final elution volume is smaller than the load volume.
Load Sample
(Black)
Step
Elute 1
Step
Elute 2
One cartridge can separate all three dyes
Step
Elute 3
NOTE: Different
strength solvents
can be used to
separate the dyes.
Stationary
Phase
Particles
b. Pass-Through Cleanup Strategy
Pass-through cleanup methods optimize matrix retention while the
analytes of interest pass-through the cartridge unretained. No sample
enrichment occurs during the solid-phase extraction (SPE) step.
1. Sample is passed through sorbent and collected
• No sample enrichment
2. Matrix interferences are retained on sorbent
Pass-Through