> 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/trusight-oncology-tumor-library-prep/library-preparation-trusight-oncology-tumor-library-prep-reference_material-list/000002919.md).

# Freeze-thaw stability of TruSight Oncology 500 (TSO500) ctDNA (v1 and v2) input and reagents

**Will repeated freeze-thaw cycles impact the cfDNA/ctDNA quantity and assay performance?**\
Illumina has not evaluated the effects of repeated freeze-thaw cycles on ctDNA/cfDNA samples. In general, it is important to limit the number of freeze-thaw cycles for cfDNA/ctDNA and commercial control samples, and this must be validated by each laboratory according to the samples used and sample handling workflows. Repeated freeze-thaw cycles may impact input quality and, therefore, quantity that can be converted into library.

**How many freeze-thaw cycles are supported for kit reagents?**

For the version 1 kit, up to eight freeze-thaw cycles are supported.

For the version 2 kit, up to six freeze-thaw cycles are supported.

**Note**: Several reagents included in each kit version are supplied in multiple tubes, allowing for a limited number of freeze-thaw cycles depending on library preparation batch sizes.

\
\
\ <br>

|                                                                                                                                                                                                                                                                                                                                                                              |
| :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------: |
| *For any feedback or questions regarding this article (Illumina Knowledge Article #2919), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000002919%20-%20Library%20Preparation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://knowledge.illumina.com/library-preparation/trusight-oncology-tumor-library-prep/library-preparation-trusight-oncology-tumor-library-prep-reference_material-list/000002919.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.