Decreasing 230/260 Ratio

Hi, I´ve isolated DNA from FFPE Tissue using the QIAamp DNA FFPE Tissue Kit, using water instead of ATE Buffer. In first measurement after DNA-isolation with ND1000 the results were good. I`ve stored the DNA at 4°C. In a remeasurement some days later the 230/260 ratio was not as good as in the first measurement and decreased further in the following weeks. Examples 230/260: 2,03 to 1,58; 2,17 to 1,63 in 20 days. Anyone who has an idea? Somebody suggested the water may have evaporated leaving relatively more salt in the tubes, but samples isolated with same Kit, stored in same tubes did not show this problem. Thanks

Sachin

The decrease in the 230/260 ratio over time is likely due to degradation or contamination resulting from storing the DNA in water. Switching to a buffered storage solution and optimizing storage conditions should help maintain the DNA’s integrity and purity over time.

You can reprecipitate the DNA or aliquot it to smaller volumes

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