> 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/microarray/general/microarray-general-reference_material-list/000001517.md).

# Recommendations for the Use and Storage of Infinium Array XC4 reagent

Infinium Arrays are coated with XC4 during the final step of the assay workflow before scanning. Proper preparation, handling and storage of the reagent, as outlined below, are essential to ensure optimal assay performance.

* The undiluted XC4 reagent is shipped at room temperature. Illumina recommends storing both undiluted XC4 and XC4 diluted with ethanol at room temperature.
* The diluted XC4 can be reused up to six times over a two-week period for a maximum of up to 48 BeadChips.
* After ethanol has been added to the XC4, Illumina recommends clearly marking the bottle as ‘Diluted’ to avoid mix-up with any undiluted XC4 bottles. Record the dilution date on the bottle to track the recommended two-week storage.
* The XC4 reagent bottle label displays the expiration date of the undiluted reagent. Illumina supports its products within the expiration date.

**Additional reference:**

* [Infinium Lab Setup & Best Practices](https://support.illumina.com/downloads/infinium-assay-lab-setup-and-procedures-11322460.html) > Best Practices > Reagents > XC4

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| *For any feedback or questions regarding this article (Illumina Knowledge Article #1517), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000001517%20-%20Microarray%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |


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