Effect of storage regime on the stability of DNA used as a calibration standard for real-time polymerase chain reaction.

This article looks at storage factors influencing the stability of potential DNA calibration standards for use in quantitative polymerase chain reaction (PCR). Target sequences from the bacteria Campylobacter jejuni were cloned into a plasmid vector. Samples of these potential calibration standards were stored at +4, -20, and -80 degrees C as aqueous and lyophilized samples and were prepared as both single-use aliquots and multiple-use preparations. Results showed that the samples stored as single-use aqueous solutions at +4 degrees C and lyophilized samples stored at +4 and -20 degrees C were the most stable. Samples stored as frozen aqueous solutions at -20 degrees C were the least stable.