15 columns and 30 tubes; sephadex g-25, fine; 2 ml column, 1.5 ml centrifuge tube, preassembled, recommended for oligonucleotides greater than 12 bases, equilibrated in 10 mm tris, 1 mm tris, 1 mm edta, 0.1 m nac1, ph 8.0, for radiolabled probes, for use in swing bucket rotors 1100 x g disposable