Copyright 2018, InnovaPrep LLC
Patented
https://www.innovaprep.com/patents
7
2
C
ONCENTRATING
P
IPETTE
M
ETHOD OF
O
PERATION
The InnovaPrep concentration process uses dead-end filtration to capture particles onto the surface of a porous
membrane filter. A novel Wet Foam Elution™ process is then employed to wash the particles off of the membrane surface
into very small liquid volumes.
2.1
C
ONCENTRATION
P
ROCESS
The concentration process of the CP Select requires single-use
Concentrating Pipette Tips (CPTs). The Pipette tips have internal filter(s)
made with either a flat membrane or a bundle of hollow fiber membranes.
The sample is drawn through the CPT, and once all the fluid has passed, it
elutes the concentrated particles through the sample port of the filter tip.
The sample is prevented from coming in contact with the instrument
fluidics, decreasing the need for between-sample decontamination and
eliminating cross-contamination or “carryover”.
The filters are hydrophilic, meaning that air is allowed to flow through only
when the membrane is dry. Once the filter has been wetted, the surface
tension of the liquid trapped in the pores of the membrane prevents air
(or any other gas) from passing through the membrane. Thus the CPTs
cannot be re-used since air trapped inside the housing cannot be pulled
through the filter prior to processing a second sample.
The concentration process is performed in the following steps:
1.
The main pump draws a vacuum on the Permeate Port. The air inside
the filter housing is drawn out and the liquid sample is pulled up through
the Sample Port.
2.
As the sample is drawn through the filter, particles larger than the
chosen membrane pore size are captured on the pores; while liquids,
dissolved solids and particles smaller than the chosen pore size pass
through the filter and into the permeate.
3.
Once the sample container is empty, air is drawn up behind the
liquid and the membrane “locks up”; leaving only the target particles on
the membrane and ending the run.
4.
When the user performs an elution, InnovaPrep’s patented Wet Foam Elution™ process is utilized. The Permeate
Port valve closes and the elution valve opens, allowing the foam to enter the Elution Port. The foam travels
tangentially down the surface of the membrane as it washes the particles from the surface. The concentrated
sample is then pushed out of the sample port into a cuvette or other container where the foam quickly breaks
back down into a small liquid volume.
Elution Port
Permeate Port
Flat
Membrane
Tip
Hollow
Fiber
Tip
FIGURE 2.1 FLAT AND HOLLOW FIBER
CONCENTRATING PIPETTE TIPS
