Detecting laboratory DNA contamination using polyester-rayon wipes: a method validation study

Due to the high sensitivity of many PCR assays, extraneous target DNA in a laboratory setting can lead to false positive results. To assess the presence of extraneous DNA, many laboratories use gauze wipes to sample laboratory surfaces. The accuracy, precision, limits of detection, linearity, and robustness of a wipe test method and each associated wipe processing step were evaluated using E. coli genomic DNA. The method demonstrated a limit of detection of 108 copies of DNA, which equates to detectable surface concentration of 4.5×10(5) copies of DNA per area sampled. Recovery efficiency or accuracy is 22±10% resulting from a >58% loss of DNA occurring at the wipe wash step. The method is robust, performing consistently despite deliberate modifications of the protocol.