The Applied Biosystems 381A DNA Synthesizer is a precision instrument which automatically performs all steps of DNA Synthesis to produce the highest quality oligonucleotides. Designed for high reliability, ease of operation and efficient use of the operator's time. Uses the phosphoramidite method of oligonucleotide synthesis because of its inherently high coupling efficiency and the stability of the starting materials. The synthesis is performed with the growing nucleotide chain attached to a solid support which is contained within a column (the reaction chamber). Solid support synthesis allows excess reagents which are in the liquid phase to be removed by filtration and eliminates the need for purification between base additions.