Lexogen Online FAQs

What concentration of targeted primers should I use?

The exact primer concentration and reaction temperatures (up to 50 °C for first strand synthesis and second strand synthesis) strongly depend on the custom primer(s) used. These need to be optimized specifically for each set of custom primers.

NOTE: The higher the primer concentration the higher the likelihood of non-specific priming.


First Strand Synthesis

The final concentration of a target-specific reverse transcription primer should be 12.5 nM – 1.25 µM in the first strand synthesis reaction.

To achieve this concentration range, you would add e.g., 5 µl of a 50 nM – 5 µM target-specific primer to the reaction.

ATTENTION! The total concentration of oligos in the first strand synthesis reaction should not exceed 2 µM.

Second Strand Synthesis


The final concentration of a target-specific second strand synthesis primer should be 0.5 µM (i.e., 2 µl of 7.5 µM Custom Target Primer).

ATTENTION! The total concentration of all oligos in the second strand synthesis reaction should not exceed 2 µM.

The annealing temperature should be chosen according to the Tm of the targeted primers and can range from 45 °- 72 °C. The extension temperature should be 72 °C.


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