> For the complete documentation index, see [llms.txt](https://knowledge.illumina.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://knowledge.illumina.com/library-preparation/general/library-preparation-general-reference_material-list/000001554.md).

# Input recommendations and considerations for Illumina DNA Prep with Enrichment (S) Tagmentation

**What are the requirements for input quality and purity?**

* **Quality**
  * Illumina DNA Prep with Enrichment (S) Tagmentation works with a wide variety of input DNA such as:\
    \- High quality genomic DNA\
    \- Fresh whole blood using the Flex Lysis Reagent Kit with the Blood Lysis Protocol\
    \- Saliva using the Saliva Lysis Protocol\
    \- DNA extracted from Formalin-Fixed Paraffin-Embedded (FFPE) samples with deltaCq ≤ 5 using the Infinium FFPE QC kit for qualification, which is recommended for optimal performance (additional information below).
  * Refer to the [Illumina DNA Prep with Enrichment Product Documentation](https://support.illumina.com/sequencing/sequencing_kits/illumina-dna-prep-with-enrichment/documentation.html) for input recommendations. Blood lysis and saliva lysis protocols are included.
* **Purity**
  * Input DNA should have an 260/280 ratio of 1.8 and 260/230 ratio of 2.0-2.2. Additionally, input DNA should not contain EDTA (if present, must be no higher than 1 mM), SDS, phenol, ethanol or other inhibiting agents such as:\
    \- Proteins that can coat DNA and prevent enzyme binding to the substrate.\
    \- Agents that can sequester enzyme cofactors (chelators) can negatively affect enzyme function.\
    \- Proteinases, detergents, and phenol can degrade enzymes.\
    \- Any chemicals left over from DNA extraction that can alter the ionic strength or pH of DNA storage buffer, which might adversely affect the tagmentation reaction.

**What is the recommended input range for the Illumina DNA Prep with Enrichment (S) Tagmentation workflow?**

* Illumina DNA Prep with Enrichment (S) Tagmentation is compatible with high quality gDNA inputs ranging from 10 ng to 1000 ng.
* For human gDNA samples and other large complex genomes, a minimum input of 50 ng is recommended.
* For degraded DNA input such as that extracted from FFPE samples, a minimum of 50 ng input is recommended.

**What is the recommended extraction method for FFPE DNA?**

* Use a nucleic acid isolation method that produces high recovery yields, minimizes sample consumption, and preserves sample integrity.

**Is there a quality requirement when using FFPE-extracted DNA as input into the Illumina DNA Prep with Enrichment (S) Tagmentation workflow?**

* Qualify FFPE DNA with the Infinium FFPE QC Kit (WG-321-1001). Quality criteria to determine the appropriate input for successful library preparation are:
  * For FFPE samples with ΔCq value of ≤ 5, the recommended DNA input is 50-1000 ng.
  * Illumina DNA Prep with Enrichment is not recommended for poor quality FFPE samples with ΔCq > 5. Using samples with ΔCq > 5 is possible but may increase chances of library preparation failure or decreased assay performance.

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| *For any feedback or questions regarding this article (Illumina Knowledge Article #1554), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000001554%20-%20Library%20Preparation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |


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