IBI MIDI FlexTubes are typically used for the extraction of proteins, RNA, DNA, or oligonucleotides (>20nt) from polyacrylamide, agarose, and or any other gel matrix in a running buffer. They are also used for dialysis or buffer change of small volumes (50-800µl), preparation of protein samples for MALD-MS, 2D gel dots extraction, and sample concentrations. IBI MIDI FlexTubes are tested by using them in extraction of proteins, RNA,or DNA fragments of various sizes from either agarose or polyacrylamide gels. IBI MIDI FlexTube kits are also tested for simple dialysis of salts or buffer exchanges. The quality of the isloated protein RNA, or DNA fragments, or of the sample after dialysis, is checked by several assays commonly used for proteins, nucleic acids, and dialysis. These devices combine two modes of action, electro-elution of macromolecules from polyacrylamide or agarose gels and buffer exchange of small volume samples. These devices allow rapid run times and high performance in either mode, and extract the macromolecules without contamination.