Bio-Rad Model 785 Vacuum Blotter - Manual (Page 9)

Section 3
Operating Instructions
3.1 Vacuum Blotter Setup
1. Set the instrument up as illustrated in the diagram below.
Fig. 3.1. Model 785 Vacuum Blotter with liquid trap, Vacuum Regulator, and pump.
2. To start, make a liquid-trap from a side-arm flask 1,500–2,000 ml. Connect the tube
from the Base Unit to the arm of the side-arm flask. Then, find a stopper for the
side-arm flask with a single hole that tightly fits a 5 ml pipet. Push half of pipet
through the stopper. Place the stopper on the side-arm flask.
3. Connect a vacuum tubing between the 5 ml pipet of the side-arm flask to the Vacuum
Regulator port.
4. Connect vacuum tubing from the Vacuum Regulator port to the Vacuum Pump. Refer
to Figure 1.
Note: Setting up for an alternative vacuum source and for two Vacuum Blotters using
the same vacuum source are discussed in Section 7.2B.
3.2 Preparation For Vacuum Transfer
1. Cut a nylon membrane 0.5 cm bigger than each border of the precut window on the
Window Gasket. Cut a sheet of filter paper the same size as the nylon membrane.
Note: The larger the membrane/filter paper, the easier the task of centering the
Window Gasket on top of the membrane.
2. When cutting a customized window from the blank Window Gasket, make sure the
window dimensions are at least 0.5 cm smaller than the gel dimensions, i.e., if the
gel is 15 x 10 cm, then the maximum window size should be 14 x 9 cm.
3.3 Gel Pretreatment
1. Fill the wells of the agarose gel with melted agarose gel of equal concentration.
Allow agarose to dry before continuing.
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