UniPrep devices function in a similar way to the Mini-UniPrep. However, UniPrep does not contain a septum in the cap and can be used to filter larger volumes (1 to 5 ml).

The UniPrep Syringeless Filter is selected based on compatibility with the sample in use. In manual operation, the filter-plunger, after the tip comes in contact with the liquid, is slowly pushed into the test tube until it stops at the bottom. The UniPrep is emptied either by decanting into a sample or autosampler vial or by drawing the filtered sample into a syringe for manual injection into an instrument.