Why my stool DNA samples have A260/280 > 2?

29 September 2023 1 9K Report

Hello,

I am extracting human DNA from stool samples using Quiagen´s QIAamp Fast DNA Stool Mini Kit. The DNA yield seems to be fine, but the A260/280 ratio is above 2.0 (2.1-2.2). What might be the cause? I am planning to use the samples for qPCR disease mutation profiling.

Paul Rutland

It may be guanidine salts washing through with the dna. Try inserting a second column wash step to clear all remnants of salts before eluting the dna and also use slightly less stool sample for the dna preparation

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