Waters Oasis Glass Cartridges - Manual (Page 2)

[ Care and Use ManUal ]
Oasis HLB Glass Cartridges 2
II. QuICk start sPe ProCedure
I. If desired, add 10 to 50 μL of internal standard to the sample
(soil, food and other solid samples require pretreatment before
SPE).
2. Adjust the sample to pH 3.
3. Place (Oasis HLB extraction cartridges on vacuum manifoldand
set vacuum to approximately 5” Hg. The extraction procedure
can also be done by positive pressure using the 5 cc Teflon
adaptors (part number 405000934).
No individual stopcocks are necessary
4. Solid-Phase Extraction Procedure: The following simple protocol
should be used in preparing and using the cartridges for the
isolation of a wide spectrum of acidic, basic, and neutral
analytes especially many classes of endocrine disruptors.
No step should be omitted.
Procedure optimization is discussed in Section III.
Note: Once the HLB sorbent has been conditioned and
equilibrated, there is no need to keep the cartridges wet prior to
sample loading. Maintain a continuous vacuum on all cartridges
throughout steps 4a-4d This convenience will save you time.
Note: For the load and elute steps, the recommended flow rate
is 10 mL/min for 5 cc cartridges. You may need to momentarily
increasethe vacuum to start the flow of aqueous solutions.
4a. Condition: Add to and draw through each cartridge 5-10 mL
10% methanol in methyl tertbutyl ether (MtBE) and then 3 mL
methanol.
4b. Equilibrate: 3 mL water
4c. Load: Draw sample through the cartridge. The maximum recom-
mended sample volume is 1 L for 5 cc cartridges.
4d. Wash: Add to and draw through each cartridge 3 mL of 5%
methanol in water (v/v). Release vacuum, remove manifold
cover, and discard waste fluids. Insert rack containing collection
vessels, replace cover, and turn on vacuum.
4e. Elute: Add to and draw through each cartridge 6 mL 10%
methanol in MtBE, If desired, evaporate eluates to dryness.
5. Reconstitute in acetonitrile and adjust to the mobile phase
concentration for LC analysis.
6. For GC analysis dry extract over sodium sulfate and reconstitute
to 1 mL.
III. adjustments to oPtImIze reCoverIes
Spike an appropriate volume of reagent water (for general analysis)
or PBS (for biological fluids analysis) with all analytes and internal/
surrogate standards. For preparation of PBS solution see Section IV.
Follow steps 4a-4e in Section II, but use a rack to collect the eluates
in the Load (4c), Wash (4d), and Elute (4e) steps in separate collec-
tion vessels. In addition, repeat step 4e with a second portion of
elution solvent and collect the eluate. Analyze all four collected
fractions. Use the table to determine adjustments, if necessary, to
optimize sample recovery.
If the fraction
from this step
contains the
analyte: Make this adjustment for optimum sample recovery:
Load (4c) The Oasis HLB sorbent has been found to retain ionized
analytes more strongly than silica-based reversed-phase
sorbents. However, recoveries may be enhanced when
analyte ionization is suppressed. For acidic analytes,
adjust the sample pH to at least two pH units below the
pKa of the acid. For basic analytes, adjust the pH to at
least two pH units above the pKa of the conjugate acid.
Wash (4d) Recoveries of very polar analytes can be increased by
using only 1 mL of water (not 5% methanol in water) as
the wash solution.
First Elution
(4e) If an acceptable recovery of analyte(s) is obtained in this
fraction (usually > 90%), no adjustments are necessary.
Second
Elution
(4e repeated) For very nonpolar analytes, stronger solvents such as
acetonitrile, methylene chloride or ethyl acetate may be
substituted, or used in sequence. In addition, for ionizable
analytes, methanol may needed to be modified with the
addition of 2% acid or 2% base, as appropriate. If solvents
stronger than methanol or acetonitrile are used for the
elution, then a preliminary conditioning step (see step 4a)
should be performed prior to the methanol conditioning
step. For example, if ethyl acetate is to be used as an
eluent, condition the cartridge with 1 mL of ethyl acetate,
followed by 1 mL of methanol and 1 mL of water.