Bond Elut Plexa™ Solid-phase Extraction Products - Crawford ...

ADVANTAGE NOTE
Bond Elut Plexa Solid-phase Extraction Products
Highly reproducible, fast flow rates
Advantage Statement: The Bond Elut Plexa family of
SPE products delivers consistent fast flow rates and
reproducible results. The absence of fines in the media
means clogging of the cartridges is significantly reduced.
This is important in the high throughput environment,
where SPE must be performed unattended and overnight,
saving valuable analysis time during the day.
Reliability is one of the key parameters when developing
high throughput sample preparation methods. For
solid-phase extraction, uniform particles with a narrow
size distribution lead to better flow characteristics for
sample addition and elution. Plexa sorbent particles are
manufactured using proprietary polymerization techniques
to achieve this very narrow distribution of particle sizes
and zero fines, yielding excellent reproducibility from
cartridge-to-cartridge. The absence of particle fines means
that the risk of frit blockage and therefore sample loss
is dramatically reduced — an important prerequisite in
the analysis of biofluids. Proprietary automated fritting
and real-time QC processes also ensure that channels or
voids in the packed sorbent bed are minimized, preventing
breakthrough of analytes due to channeling. All of these
features contribute to reproducible data and improved
method ruggedness. In addition, the polymer architecture
itself enables simple protocols for robust and troublefree
SPE applications. Innovative research, state-of-the
art manufacturing and monitoring within a stringent
quality system has produced the latest generation of high
performance SPE products: Bond Elut Plexa and Plexa PCX.
Excellent particle integrity
Bond Elut Plexa shows excellent particle integrity with
no oversized, damaged or fine particles. In contrast, the
alternative polymer shows lots of broken particles and
fines that may cause frit blockage and potential sample
loss (Figure 1). Working with these alternative cartridges
means additional time and work to attend the SPE process.
Bond Elut Plexa Alternative Polymer
Figure 1. Comparison of particle sizes of non-polar SPE polymers by
imaging analysis.
Narrow particle size distribution
A comparison of the particle size distribution between
alternative products demonstrates nearly the same mean
particle diameter for both, but significant differences in
the shape of distribution (Figure 2). Bond Elut Plexa has
a Gaussian-type distribution, whereas the alternative
polymer shows a broad distribution with broken and fine
particles. What are the practical results? The consequences
of the broader size distribution are slower flow rate,
greater risk of blocked wells, and decreased precision
(less reproducibility from cartridge-to-cartridge and
well-to-well).
Figure 2. Comparison of particle size distributions of non-polar SPE
sorbents. Bond Elut Plexa, mean particle size 46 µm . Alternative Polymer,
mean particle size 47 µm.

Bond Elut Plexa Solid-phase Extraction Products
Bond Elut Plexa
Acidic
Method optimized for acids
1. Condition: 500 µL CH 3 OH, followed by 500 µL water
2. Apply 100 µL plasma diluted 1:3 with 1% formic acid
3. Wash: 500 µL 5% CH 3 OH
4. Elute: 500 µL CH 3 OH
Simple protocols
Bond Elut Plexa
Bond Elut Plexa, the non-polar polymer, is universally
applicable and the best choice for the extraction of a wide
range of acidic, neutral and basic analytes from different
matrices.
Bond Elut Plexa PCX
Bond Elut Plexa PCX is a cation exchanger with mixedmode
sorbent characteristics and therefore suitable for
the extraction and clean-up of weak bases from biofluids.
Bond Elut Plexa PCX demonstrates the same excellent
distribution and outstanding particle integrity as Bond
Elut Plexa. A highly controlled sulfonation process results
in zero fines for Bond Elut Plexa PCX. Figure 3 shows the
general protocol for trouble-free SPE applications with
either Bond Elut Plexa or Bond Elut Plexa PCX.
Faster flow rates and no clogging
The practical effect of particle integrity on flow rate is
shown in Figure 4. To compare flow rates between Plexa
PCX and another CX polymeric sorbent, 12 wells were
conditioned with 500 µL methanol followed by 500 µL
of water. Plasma, diluted to 1:3 with phosphoric acid,
was then added to every well, and a constant vacuum of
5 in. Hg was applied. The time was recorded, enabling
flow rates to be calculated.
Neutral
Method optimized for bases and neutrals
1. Condition: 500 µL CH 3 OH, followed by
500 µL water
2. Apply 100 µL plasma diluted 1:3 with
2% NH 3
3. Wash: 500 µL 5% CH 3 OH
4. Elute: 500 µL CH 3 OH
Plexa PCX
Basic
Mixed-mode method optimized for bases
1. Condition: 500 µL CH OH, followed by 500 µL water
3
2. Apply 100 µL plasma diluted 1:3 with 2% H PO 3 4
3. Acidic wash: 500 µL aqueous 2% formic acid
4. Neutral Wash: 500 µL CH OH-CH CN (1:1, v/v)
3 3
5. Elute: 500 µL CH OH-CH CN + 5 % NH (28-30%)
3 3 3
Figure 3. General acid/basic screening using Bond Elut Plexa and Plexa PCX. Indicated volumes are based on Bond Elut 96 Plexa 10 mg plate.
For SPE cartridges, elution volume should be 1-2 mL, with higher volumes for less polar analytes.
Flow rate (mL/min)
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
1 2 3 4 5 6 7 8 9 10 11 12
Well Number
Figure 4. Plexa PCX (blue) demonstrates faster and more reproducible
flow rates. Mean flow rate for Plexa PCX = 0.47 mL/min (%RSD = 24%),
alternative CX polymer mean flow rate = 0.27 mL/min (%RSD=38%).
Typical properties
Parameters Bond Elut Plexa Bond Elut Plexa PCX
Pore size (nominal) 120 Å 120 Å
Particle size 45 µm 45 µm
Specific surface
area m2 /g
450 m2 /g 450 m2 /g
pH range stability 1-14 1-14
Chemical resistance
(solvents)
Retention capacity
/ Ion exchange
capacity
Broad range of protic
and non-protic polar
and non-polar solvents
10% of sorbent mass*
Broad range of protic
and non-protic polar
and non-polar solvents
Cation exchange
loading of 1.0 mmol/g
(determined by
elemental analysis of
sulfur content)
*highly dependent on matrix type and specific analyte characteristics
These properties are characteristic but do not constitute specifications.
PCX
Other CX Polymer

Bond Elut Plexa Solid-phase Extraction Products
Conclusion
Higher bed packing efficiency in an SPE device is achieved
if the sorbent particles have a very narrow size distribution.
This leads to higher performance. SPE sorbents that contain
a large degree of fines will cause blockage of the sample
and lead to a slow, variable flow of solvent and analyte
through the sorbent bed. Thus, assay variability with respect
to recovery rates will increase.
Bond Elut Plexa sorbent particles are nearly mono-dispersed
in size, resulting in a very homogeneous packing. Therefore,
reproducible results with excellent recoveries and sharp
elution profiles are the standard. Bond Elut Plexa products
are highly amenable to a high throughput or automated
platforms due to excellent well-to-well and cartridge-tocartridge
flow reproducibility.
Varian, Inc.
www.varianinc.com
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