Spiking custom primers into the Illumina sequencing primers

08/24/18


Libraries prepared with custom sequencing primers require optimization to perform successfully on Illumina sequencing platforms. Combining (or “spiking”) custom primers into the Illumina primers is necessary when including PhiX or other standard Illumina libraries with the custom sample. Illumina cannot guarantee the performance or compatibility of custom primers, and it is up to the customer to validate primers for sequencing on a specific platform. When using custom sequencing primers, it is critical to know the recommended platform-dependent loading concentration, total volume, loading positions, and primer annealing temperatures. This bulletin provides information for spiking custom primers into the Illumina primers.

Spiking custom primers into Illumina primers

  • The cartridge position, total volumes, and final concentration of custom primers for each platform are provided in the tables below.
  • Calculate the volume of the custom primer to add to the Illumina primer cartridge position based on the final concentration of the custom primer in the cartridge.*
  • After spiking in the custom primer, adjust the pipette to half of the total volume and gently pipette up and down five times to mix thoroughly.
  • For MiSeq, MiniSeq, NextSeq and NovaSeq platforms, do not check the “custom primer” box position in the sample sheet or during the run setup.

* To calculate how much custom primer to spike into the well, use the (C1)(V1) = (C2)(V2) equation where:

C1 = the concentration of your custom primer (when using high concentration primer stock, such as 100uM, the small additional volume to the final volume is negligible).

V1 = solve for the volume of the custom primer to be spiked in

C2 = the recommended custom primer final concentration from the chart below

V2 = total volume of Illumina primer in the charts below

Example: (100uM * V1) = (0.5uM * 680uL)
                                 V1 = 3.4 µl

Important Note: The guidelines below are based on the current primer volumes. To ensure accuracy, measure total primer volumes in the cartridge with a pipette before proceeding with setup.

iSeq100
Due to the construction of the iSeq100 cartridge, it is not possible to load and use custom primers.

MiniSeq
Because of the unique dual-indexing workflow on the MiniSeq, combinations of custom primers and Illumina primers are limited. Be aware of the custom primer dependencies outlined here.

NextSeq
Because of the unique dual-indexing workflow on the NextSeq, combinations of custom primers and Illumina primers are limited. Be aware of the custom primer dependencies outlined here.

MiSeq

* There is no option for a custom Index 2 (i5) primer since the template uses the grafted P5 primer on the surface of the flow cell

HiSeq 1000/2000 - 1500/2500

* There is no option for a custom Index 2 (i5) primer since the template uses the grafted P5 primer on the surface of the flow cell

HiSeq 3000/4000

NovaSeq
Because of the primer design and dual-indexing workflow on the NovaSeq, combinations of custom primers and Illumina primers are limited. Be aware of the custom primer dependencies outlined here.

* There is no option for a custom Index 2 (i5) primer since the template uses the grafted P5 primer on the surface of the flow cell

Using Custom Primers in Place of Illumina Primers

If only the custom primer is needed, custom primers can be used in place of the Illumina primers. For instructions on how to set up a run using only custom primers, see the following guides:

For more information on the indexing strategies for each instrument, refer to the Indexed Sequencing Overview Guide.