> 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/dna-library-prep/library-preparation-dna-library-prep-faq-list/000003432.md).

# DNA Input Requirements for Illumina DNA PCR-Free Library Prep

**How much DNA is optimal for Illumina DNA PCR-Free Prep?**\
High-quality libraries can be generated using 25-2000 ng of input DNA. For optimal performance, when sample quantity permits, Illumina recommends using saturating amounts of DNA (at least 300 ng for gDNA along with the recommended raw sample volumes for integrated extraction options).

**What are the consequences of using lower or higher than the recommended input?**\
At lower input amounts, reduced yield and smaller insert size may be observed. Input amounts greater than 2000 ng have not been tested.

**How should the quality of the input DNA be assessed?**\
Refer to theDNA Input Recommendations and Assess Purity sections of the [Reference Guide](https://support.illumina.com/downloads/illumina-dna-pcr-free-reference-guide.html).

**What DNA extraction methods are recommended by Illumina for input materials used with the Illumina DNA PCR-Free kit (eg, blood, saliva, dried blood spots)?**\
Refer to the DNA Input Recommendations and the Supplementary Information sections of the [Reference Guide](https://support.illumina.com/downloads/illumina-dna-pcr-free-reference-guide.html).

**Is it possible to increase yield from whole blood or dried blood spots (DBS)? Can additional input be used? Can the Bead-Linked Transposomes PCR-Free (BLT-PF) volume be increased to 15 µl, as in the standard purified gDNA protocol? What about saliva input?**

It is important to follow the instructions in the protocol. Changing the amount of input blood or saliva, or modifying the BLT-PF volume may compromise assay performance.

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| *For any feedback or questions regarding this article (Illumina Knowledge Article #3432), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000003432%20-%20Library%20Preparation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |


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