The use of Poly-Pak™ packings in cartridges or barrels overcomes several disadvantages usually associated with reverse phase (RP) cartridges. The packing is stable in the pH range 1-13, thus the ammonium hydroxide solution, diluted with water, is loaded directly onto the packing. Also, after elution of failure sequences, the trityl group is removed and washed from the support-bound oligonucleotide. The fully deprotected product can then be eluted and isolated by lyophilization. Poly-Pak™ Cartridges may also be used for desalting normal or labelled oligonucleotides. The original Poly-Pak cartridge and barrel are designed for 0.2 µmole syntheses or less. Poly-Pak II cartridges and barrels are designed for use with 1 µmole syntheses. A booklet, User Guide To Poly-Pak™ Cartridge Purification, describes in detail the process and several applications. This booklet is available online at: http://www.glenresearch.com/Technical/PolyPakBooklet.pdf.