For easy ordering, check out out the Invitrogen™ Custom DNA oligos page.

From simple to complex, we have your bases covered

  • The world’s highest capacity, resulting in prompt, reliable delivery
  • Computer-controlled synthesis system eliminates manual data transfer and re-entry data, allowing for accurate QC and shipping
  • quality control and validation of suppliers and raw materials includes 100% in-process trityl monitoring in real time and post-synthesis QC by capillary electrophoresis

Invitrogen™ Custom DNA oligos are synthetic oligonucleotides made according to your specifications and can be used in a variety of applications, from PCR and sequencing to probes for gene detection. Custom oligos are offered with standard deoxynucleotides, modified bases, and 5´- and 3´-modified nucleotides. Available modifications include fluorescent dyes, enzyme conjugates, and S-oligos for antisense studies. We offer five standard synthesis scales and four purity options (Table 1).

Why do oligos sometimes require purification?

Oligos are made using a DNA synthesizer, a computer-controlled reagent delivery system. DNA is synthesized in the 3’ ⇒ 5’ direction, and each base addition is accomplished through a series of chemical reactions. But no chemical reaction is 100% efficient; during DNA synthesis, the maximum coupling efficiency obtainable is normally around 99%. Therefore, approximately 1% of the growing nucleotide chains fail to couple to a base in each round. In the case of a 30-mer oligo synthesis, the final product would also contain 29-mer failures, 28-mer failures, etc. For an oligo of this length, the percentage of full-length oligo is estimated to be between 74% and 54%, assuming a 99% or 98% reaction efficiency. The percentage of full-length oligo produced decreases as the length of the oligo increases.

The failure sequences inherent in the oligo synthesis process can compete with the full-length product in some applications; therefore, to help ensure success in downstream experiments, it may be necessary to purify the full-length oligo away from the failure sequences.

Table 1. Benefits of Custom DNA oligo purification methods.

Purification method Description Benefit
Desalt Oligos are processed through normal phase chromatography columns which removes salts but not failure sequences A salt-free DNA solution, ready to use; suitable for many PCR and sequencing applications without further purification
Cartridge Based on reversed-phase chromatography; removes failure sequences from the completed synthesis Provides full-length sequences needed in some applications
HPLC Reversed-phase high-performance liquid chromatography (HPLC) removes failure sequences or unincorporated label the same way as cartridge purification Guarantees highly purified primer required in some applications (≥85% full-length)
PAGE Method used to differentiate full-length product from failure sequences based on size and conformation Provides the highest percentage of full-length oligos (≥85%) required for certain demanding applications such as mutagenesis or adapter production


For easy ordering, check out out the Custom DNA oligos page.