Question: Can I substitute MilliQ water for nuclease-free water in the Xenium workflow?
Answer: At many steps in both the Xenium In Situ Gene Expression assay and Xenium Analyzer workflow, nuclease-free water (Thermo Fisher Scientific, AM9937*) is a required third-party reagent. It is not possible to substitute MilliQ** water for nuclease-free water for the assay workflow. The Xenium workflow has been carefully designed to maintain RNA integrity and this reagent swap may compromise assay performance.
For the Xenium Analyzer instrument run, it is possible to substitute nuclease-free MilliQ water for nuclease-free water (Thermo Fisher Scientific, AM9937*) in the Xenium Sample Wash Buffer A and the Xenium Probe Removal Buffer. We have tested nuclease-free MilliQ water filtered by the Millipore Sigma Biopak® Polisher system***. We observed there was comparable performance between the Millipore Sigma system and bottled Thermo Fisher Scientific water. This reagent swap is validated for instrument buffers only.
Millipore Sigma Biopak® Polisher filter (CDUFBI0A1) compatible with Sigma Milli-Q® IQ/IX/EQ systems.
Best practices for the MilliQ filtration systems (for Xenium Analyzer buffer preparation):
- Confirm the system can produce MilliQ water that is nuclease-free.
Before usage of nuclease-free MilliQ water, perform a systems check to make sure consumable parts are not expired.
This can be accessed through filtration system UI for the consumables and also through visual inspection of the component as shown below.
- Example of expired component:
*Alternate brands of nuclease-free water are low-risk reagent swaps: Can I use alternative third-party reagents for Xenium?
**It is possible to substitute nuclease-free (not DEPC-treated) water for any step that calls for MilliQ water.
***Other filtration systems have not been tested and are therefore are unsupported as we cannot confirm assay performance.
Products: Xenium In Situ Gene Expression