NCJ Number
240059
Journal
Forensic Science International: Genetics Volume: 6 Issue: 5 Dated: September 2012 Pages: 511-522
Date Published
September 2012
Length
12 pages
Annotation
Due to some failure to extract DNA from samples that should have produced DNA using validated automated DNA IQ-based protocol, the competition for binding sites on the DNA IQ magnetic beads was more closely examined.
Abstract
The Promega DNA IQ system is easily amenable to automation and has been an integral part of standard operating procedures for many forensic laboratories, including those of the Royal Canadian Mounted Police (RCMP) since 2004. In the current study, Heme from heavily blooded samples interfered slightly with DNA binding. Increasing the concentration of Proteinase K during lysis of these samples did not enhance DNA recovery. However, diluting the sample lysate following lysis prior to DNA extraction overcame the reduction in DNA yield and preserved portions of the lysate for subsequent manual or automated extraction. Dye/chemicals from black denim lysates competed for binding sites on the DNA IQ beads and significantly reduced DNA recovery. Increasing the size or number of black denim cuttings during lysis had a direct adverse effect on DNA yield from various blood volumes. The dilution approach was successful on these samples and permitted the extraction of high DNA yields. Alternatively, shortening the incubation time for cell lysis to 30 min. instead of the usual overnight at 56 degrees C prevented competition from black denim dye/chemicals and increased DNA yields. (Published Abstract)