Effective removal of co-purified inhibitors from extracted DNA samples using synchronous coefficient of drag alteration (SCODA) technology

Various types of biological samples present challenges for extraction of DNA suitable for subsequent molecular analyses. Commonly used extraction methods, such as silica membrane columns and phenol-chloroform, while highly successful may still fail to provide a sufficiently pure DNA extract with some samples. Synchronous coefficient of drag alteration (SCODA), implemented in Boreal Genomics' Aurora Nucleic Acid Extraction System (Boreal Genomics, Vancouver, BC), is a new technology that offers the potential to remove inhibitors effectively while simultaneously concentrating DNA. In this initial study, SCODA was tested for its ability to remove various concentrations of forensically and medically relevant polymerase chain reaction (PCR) inhibitors naturally found in tissue, hair, blood, plant, and soil samples. SCODA was used to purify and concentrate DNA from intentionally contaminated DNA samples containing known concentrations of hematin, humic acid, melanin, and tannic acid. The internal positive control (IPC) provided in the Quantifiler™ Human DNA Quantification Kit (Life Technologies, Foster City, CA) and short tandem repeat (STR) profiling (AmpFℓSTR® Identifiler® Plus PCR Amplification Kit; Life Technologies, Foster City, CA) were used to measure inhibition effects and hence purification. SCODA methodology yielded overall higher efficiency of purification of highly contaminated samples compared with the QIAquick® PCR Purification Kit (Qiagen, Valencia, CA). SCODA-purified DNA yielded no cycle shift of the IPC for each sample and yielded greater allele percentage recovery and relative fluorescence unit values compared with the QIAquick® purification method. The Aurora provided an automated, minimal-step approach to successfully remove inhibitors and concentrate DNA from challenged samples.