Custom DNA Oligos

Our experience with gene construction and macroarray development provides us with insight into the potential difficulties of long oligo synthesis. We have developed techniques to purify long oligos, which are unmatched by other suppliers.


Our synthesis platforms provide a superior coupling efficiency which enables us to routinely synthesize oligos up to 110 bases. Our chemists have developed QC techniques including mass spectrometry for oligos up to 70 bases. We can match the level of purity and quality needed based upon your application.


  1. Synthesis Scales
    Oligos up to 110 bases may be synthesized at 0.05, 0.2, and 1.0 µmole scales. Contact your Account Representative for long modified oligos or oligos greater than 110 bases.
  2. Purification
    All Sigma-Genosys oligos include desalting and deprotection at no additional charge. Since stringent applications may require additional purification, PAGE purification is recommended for oligos greater than 50 bases. If you are unsure about the purification level you need for your research, see our technical bulletin entitled Selecting the Best Purification or contact our Technical Support staff for assistance.
  3. Pricing
    Unlike other suppliers, there is no additional charge for long oligo synthesis.
  4. Minimum Yield
    Yield will vary based upon base composition, purification, oligo length, scale and modifications. That’s why we have set minimum yield standards – guaranteed quantity.
  5. Shipping Schedule
    Oligos greater than 50 bases will ship within 3 – 4 days. See our Shipping Schedule for a complete list of expected shipment times. Our Customer Service department is available to answer any questions on your order status.
  6. Guaranteed Quality
    Oligos are routinely checked for length, purity, and composition. Long oligos are typically quality checked by PAGE, ESI-MS, and/or CE. Our global quality control capabilities include MALDI-TOF mass spectrometry, electrospray ionization mass spectrometry (ESI-MS), capillary electrophoresis (CE), and polyacrylamide gel electrophoresis (PAGE). If you are dissatisfied and report an oligo problem within 30 days of order receipt, we will gladly remake your oligo free of charge or provide a credit for the purchase amount.
  7. All orders are shipped with a Quality Assurance document that includes measured yields, melting temperature, MW and µg/OD with every oligo. Oligos in tubes are accompanied by an extra vial label for your records.