The separation column is placed into a waste tube and the solution containing the DNA and/or RNA (usually a lysed cell suspension) is pipetted into the top of the separation column and then this is centrifuged to force the fluid through the barrier which binds the DNA/RNA. Then several washes using a wash solution (usually two washes) are done in a similar way using centrifugation to force the wash solution through the barrier. The DNA/RNA which is still bound to the barrier in the separation column is then eluted from the barrier by adding pre-heated eluting solution or water.

Then placing the separation column into a collecting tube and again using centrifugation to force the eluting solution or water through the barrier. This time the DNA and/or RNA is eluted off the barrier and collected in the collection tube.

This method has several problems. There are several centrifugation steps involved requiring a special centrifuge which can accommodate the separation columns. The centrifugation steps are also timeconsuming and require several loading and unloadings of the centrifuge. The number of samples processed at one time is limited to the number of positions available in the centrifuge. The separation columns need to be transported from the area of processing to and back from the centrifuge, so the whole process cannot be done completely in one area, a safety hood for example.

This increases the risk of cross contamination via aerosols.

These problems are overcome by the present invention, which provides a method of using the separation column without centrifugation. The fluids are forced through the separation column barrier by air pressure. There is no need of a special type of centrifuge that can accommodate the columns. The steps are much faster to do and there is no need for loading or unloading the separation columns. The number of samples processed at one time can be greatly increased and the device can be set for small or large numbers. There is no transportation of the columns from the place of processing, so the whole procedure can be done in a safety hood. The risk of cross contamination is thus reduced.

The basic principle of the invention is to force fluid through the separation column by increased air pressure from above the fluid. This invention utilises a simple plunger within a syringe type pump to deliver the increased air pressure. This makes this invention portable and without the need for any extra devices to operate it.

The invention consists of a waste container over which is placed a plate in which the separation columns can be secured. This plate may be arranged to accommodate many separation columns in tandem. The separation columns are placed into this plate which holds the columns in position so that the lower part of the columns, from which fluid is expelled, is in the waste container. The next part of the invention is another plate which fits over the top of the separation column. This plate has syringe like devices attached, the nosells of which are directly over the separation columns through holes in this second plate. This plate also has a seal or plug which forms an air tight seal over the top of the separation column. The syringe devices above the columns are simply air tight plungers within tubes, very much like syringes for drawing blood. The plungers can all be connected at the top by another plate so that they may all be depressed together.

In one form of the invention (figure 1) the separation columns (3) are placed onto a waste container (1) via a securing plate (2). The fluid containing the DNA and/or RNA is pipetted into the top of the column. The top plate (5) with the syringe like plunger devices (6) is paced in position over the separating columns (the plungers in the up position). An air tight seal is made between the top plate and the separating column by a seal or plug (4) which may be made from rubber or any material which would provide an air tight seal. The plunger is pressed down and the resulting increase in air pressure above the fluid in the separating column forces the fluid through the barrier which bounds the DNA and/or RNA. The waste fluid is collected in the waste container. The top plate can then be removed so that the wash solution can be added into the separation column. The plungers are pulled into the up positions using the plunger plate (7) and the top plate is again placed in position over the separation columns and pressed down to force the fluid through the separation column in a similar way to the original fluid containing the DNA and/or RNA. Several washes may be made but usually two is sufficient. After the washes have been done the DNA and/or RNA can then be eluted into the collection tubes. The top plate is removed and the securing plate with the separation columns are removed from the waste container and placed in position over a rack containing the labelled collection tubes. The pre-heated elution solution or water is pipetted into the separation column, the plungers pulled to the up position and the top plate is placed in position over the separation column.

The plungers are pushed down and the resulting increase in air pressure forces the elution solution or water through the barrier eluting the DNA and/or RNA off the barrier and collecting the DNA and/or RNA into the collecting tubes. The device can have a large number of these units of separation in tandem and so can extract a large number of samples at one time.

In another form of the invention, there is only one plunger which is connected to the separation columns via tubes and plugs form a seal (figure 2). In another form the single plunger can be attached to a cover plate which seals off all the separation columns in one cover area (figure 3).

However the form of the invention in figure 1 forms a separate self contained seal for each individual separation column and so would reduce the chances of cross contamination. In yet another form of the invention the securing plate itself could form the column and the barrier in hich the DNA/RNA is attached could be itself placed in the securing plate columns. Thus the top of the securing plate columns could have the seals on the upper rim, rather than the seals being on the top plate if desired (figure 4). Thus the actual barrier is just replaced each time a separation is to be done. This however means that the inside of the securing plate column would have to be washed and decontaminated between each separation as cross contamination may be a problem.