> 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/accessory-products/library-preparation-accessory-products-faq-list/000005128.md).

# Can PhiX and denatured PhiX be stored and used again?

Store non-denatured, undiluted 10 nM stock PhiX at -25°C to -15°C until the expiration date.

Use the following recommendations for PhiX dilutions. Note that if the tube expiration date comes before any of the following storage timelines, performance is not guaranteed after the expiration date.

* Store non-denatured, diluted 4 nM PhiX at -25°C to -15°C for up to 3 months.
* Store the denatured, diluted 20 pM PhiX at -25°C to -15°C for up to 3 weeks. After 3 weeks, cluster numbers tend to decrease.
* For use with the NextSeq 500/550: Store the denatured 1.8 pM PhiX at -25°C to -15°C for up to 2 weeks. After 2 weeks, cluster numbers tend to decrease.

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| *For any feedback or questions regarding this article (Illumina Knowledge Article #5128), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000005128%20-%20Library%20Preparation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |


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