Using the Stirred Cell Concentrator

Obtain a 44 mm membrane for the concentrator. Handle the membrane by touching only its edges.
Place the membrane, shiny side down, in a beaker of nanopure water (100 mL).
Change the water in the beaker three times over the next hour. This ensures that the storage buffer is completely removed from the membrane before use.
Collect all of the parts needed to assemble the concentrator. Consult the manual if necessary.
Lubricate the two red O-rings adequately. You should be able to slide your gloved fingers easily around them.
When the membrane is clean, place it shiny side up on the grooved bottom piece of the concentrator.
Place a red O-ring on the top of the membrane. Be sure to not get any lubricant all over the shiny surface.
Place the cell body over the grooved piece and membrane and screw on the bottom plate. Ensure that the cell is sealed but do not over tighten.
Place the stir bar insert into the concentrator cell.
Insert the sample that is to be concentrated into the cell. Do not exceed the 50 mL mark.
Slide the top of the concentrator onto the cell. It should go on easily. Forcing the lid on will dislodge the O-ring. Apply more lubricant to the O-ring if necessary.
Turn the pressure release valve (black lever) on the cap to the horizontal position.
Screw the gas inlet onto the cap. Do not over tighten.
Place the cell into the retaining stand and turn the pressure release valve to the vertical position. Place the cell and stand on a stir plate.
Turn on the air pressure slowly.
Set the regulator to 50-55 psi. Do not let the pressure exceed 75 psi.
Once the cell is pressurized, start stirring. The vortex should go down 1/3 of the total volume of the liquid.
Concentrate to a volume greater than 2.5 mL.
Turn off the air pressure.
Turn the pressure release valve to the horizontal position to relieve pressure.
Disassemble and clean.