Short Answer: Preserved samples remain stable for up to 6 months
Scenario: Imagine you’re collecting a water sample in the field and knowing you cannot ship it for days or even weeks. Or perhaps you’re planning a monitoring program where samples must be batched before analysis.
Later you wonder, is the DNA in my sample still the same as it was when I collected it?
Genecount® qKit Preserve was designed with situations like these in mind, so the answer is yes.
This article explains how we know that, what testing was performed, and why we confidently support a six month hold time for preserved samples.
How was DNA stability evaluated?
Rather than testing samples under normal storage conditions, we asked a much harder question: What happens to preserved DNA under extreme heat?
If DNA can maintain quality in those conditions, it can certainly survive storage, shipping, and field handling. This is called accelerated stability testing which is a method commonly used in molecular biology, pharmaceuticals, and diagnostic development to predict long-term stability in a short period of time.
In our stability testing, Preservation Buffer A tubes were spiked with a known amount of DNA. These tubes were then exposed to elevated temperatures for seven days. At multiple points, DNA recovery was measured using the standard qKit Purify Auto workflow followed by qPCR analysis.
These studies showed that preserved DNA remains highly stable over extended periods even when exposed to challenging temperature conditions.
What does the data show?
Figure: Preserved DNA Recovery at 75ºC
The figure above illustrates the stability of DNA in Preservation Buffer A over time. Each tube was spiked with a consistent copy number of DNA template. Tubes were incubated at 75ºC over seven days, with replicates from each day removed from incubation and placed in a refrigerator at 4ºC until the end of treatment. Following treatment, each tube was processed using the qKit Purify Auto procedure and amplified with the appropriate qPCR master mix. The minimal loss due to thermal degradation at the end of seven days (~1 log) indicates significant stability over time with a conservative preserved shelf life of six calendar months.
Why is this important?
Seven days at 75ºC is an intentionally harsh test. It represents conditions worse than typical storage, transport, or laboratory environments.
Even under those conditions, DNA showed minimal loss. That is why we can confidently say that DNA preserved with GeneCount qKit Preserve is highly stable over time.
Because this testing used such extreme conditions, the calculated hold time of six calendar months is intentionally conservative.
What is the validated hold time?
Up to 6 months
Six months is the validated hold time for DNA stability in samples preserved using Genecount® qKit Preserve. This timeframe reflects the duration evaluated through extrapolation of accelerated aging results and represents the period for which sample stability has been confirmed. While internal data suggest that preserved DNA may remain stable beyond six months, extended hold times have not been formally validated and are not currently claimed.
How does preservation make this possible?
Genecount® qKit Preserve works by immediately inactivating microbial cells and stabilizing nucleic acids at the time of preservation. This prevents biological activity, changing population dynamics, or degradation after collection, helping ensure that the sample remains representative of conditions at the time it was preserved.
For more detail on the benefits of preservation kits, please see How does GeneCount qKit Preserve improve microbial sample preservation?
What are the best practices for the most reliable results?
To ensure optimal results, we recommend the following:
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Preserve samples immediately at the time of collection whenever possible.
If preservation cannot be completed at the collection site, keep samples on ice in a cooler and preserve them within the same business day, up to 8 hours.
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Submit samples for analysis as soon as practical within your project timeline.
Once samples have been properly preserved, there is no need to ship them on ice or with ice packs. This added flexibility simplifies logistics while maintaining sample integrity and reproducibility.
These practices help maximize reproducibility while still taking full advantage of the flexibility provided by preservation.
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