User Manual

5. Check the wells after sample has been applied to ensure that there are no air bubbles in
the wells. Air bubbles will prevent the sample from binding to the membrane. Air bubbles
may be removed by pipetting the liquid in the well up and down.
6. Proper positioning of the flow valve relative to the level of the apparatus is important for
proper drainage. The speed of filtration is determined by the difference in hydrostatic
pressure between the fluid in the sample wells and the opening of the flow valve which is
exposed to air. If the opening of the flow valve is above the level of the sample wells, very
little drainage will occur. When the flow valve is positioned at a level below the sample
wells, proper drainage will occur during filtration applications.
7. The best method for removing the blotted membrane from the BioDot apparatus is to
leave the vacuum on following the wash step. With the vacuum on, loosen the screws
and remove the sample template. Next, turn off the vacuum and remove the membrane.
8. A method for applying gentle vacuum to the apparatus is to adjust the flow valve so that it
is open to air, the vacuum source, and the vacuum manifold, while the vacuum is on.
Then, use a finger to cover the valve port exposed to the atmosphere. The amount of
vacuum reaching the manifold will be regulated by the pressure of your finger on the
valve.
9. For applications using glass membranes that might break under vacuum pressure, an
extra piece of tubing can be attached to the flow valve to increase hydrostatic pressure
during wash steps. This tubing should extend approximately 2–3 feet below the level of
the apparatus, usually to a waste receptacle on the floor. With this increased hydrostatic
pressure, fluid will drain from the apparatus in 3–4 minutes. This type of gentle pressure is
also useful for binding nucleic acids to nitrocellulose or Zeta-Probe membranes.
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