# BLT PF usage FAQ for Illumina DNA PCR Free

**Note:** The BLT-PF reagent is the bead linked transposome reagent used in the Illumina DNA PCR-Free workflow.

**Can 10 µl of BLT-PF be used (like in the integrated extraction protocol) for purified gDNA?**\
No, this will impact sequencing metrics.

**If saliva/blood input is quantified, can 15 µl BLT-PF be used instead? What would happen? (in “Tagment Genomic DNA” section of Reference Guide)**\
This will increase the amount of DNA required for the integrated normalization. For some samples, this may negatively impact the self-normalization feature of the Illumina DNA PCR-Free method.

**Why is there a different amount of BLT-PF if using gDNA vs blood or saliva input?**\
This is intended to make sure that raw samples are normalized as they are processed through the workflow, allowing for utilization of the normalizing effect of the bead linked transposome.

**Should DBS be treated like gDNA (using 15 µl BLT-PF) or like blood/saliva (using 10 µl BLT-PF) in the “Tagment Genomic DNA” section of the Reference Guide?**\
Treat like blood/saliva samples--add 10 µl BLT-PF.

**What happens if the beads precipitate out of solution?**

Resuspend beads and proceed as normal.

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| *For any feedback or questions regarding this article (Illumina Knowledge Article #3453), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000003453%20-%20Library%20Preparation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |


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