# Freeze thaw stability of TruSight Oncology 500 (TSO500) ctDNA (v1 and v2) input and reagents **Will repeated freeze-thaw cycles will impact the cfDNA/ctDNA quantity and impact assay performance?**\ Illumina has not tested repeated freeze thaws of cfDNA samples. In general, it is important to limit the number of freeze thaws for cfDNA/ctDNA and commercial control samples, and this must be validated by each lab according to the samples used and sample handling workflows. Repeated freeze-thaw cycles may impact input quality and, therefore, quantity that can be converted to library. **How many freeze-thaw cycles are supported for kit reagents?** For the version 1 kit: Eight freeze-thaw cycles are supported. For the version 2 kit: Six freeze-thaw cycles are supported. **Note**: Several reagents included in each kit version are supplied in multiple tubes, allowing for limited freeze-thaw cycles depending on library preparation batch sizes. \ \ \
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