# BLT PF handling for the Illumina DNA PCR Free workflow questions

**Why does the BLT-PF tube have to stay upright in storage?**\
Illumina recommends that the BLT-PF stay upright in storage to enable easy resuspension and avoid bead drying. Make sure beads are thoroughly mixed and resuspended prior to use.

**If there bead residue that dried inside the BLT-PF tube, is it a problem?**\
No, proceed as normal, but try to resuspend by inversion and vortexing.

**How to proceed if too much or too little BLT-PF is added to a sample?**\
Using less or more of BLT-PF will impact library yield and size distribution. If various amounts of BLT-PFs were used to create libraries, Illumina recommends individually quantifying the libraries before pooling. Libraries may still be sequenced, though certain sequencing metrics may be affected.

**How to proceed if the samples with BLT-PF are left on the magnet longer than is stated in the protocol?**\
Leaving BLT-PF on the magnet for several extra minutes does not lead to any downstream issues with library prep; however, Illumina does not recommend leaving the library prep for long stretches of time (>10 minutes).

**What happens if BLT-PF beads dry?**\
Overdried BLT-PF beads can reduce library yield.

**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 #3454), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000003454%20-%20Library%20Preparation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |


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