Resumen de The use of Hemastix® and the subsequent lack of DNA recovery using the Promega DNA IQTM system
Hiron Poon, Jim Elliott, Jeff Modler, Chantal Frégeau
Following implementation of our automated process incorporating the Promega DNA IQTMsystem as a DNA extraction method,a large number of blood-containing exhibits failed to produce DNA. These exhibits had been tested with the Hemastix® reagent strip, commonly usedby police investigators and forensic laboratories as a screening test for blood. Some exhibits were even tainted green following transfer of the pre-sumptive test reagents onto the samples. A series of experiments were carried out to examine the effect of the Hemastix® chemistries on the DNAIQTMsystem. Our results indicate that one or more chemicals imbedded in the Hemastix® reagent strip severely reduce the ability to recover DNAfrom any suspected stain using the DNA IQTMmagnetic bead technology. The 3,3¢,5,5¢-tetramethylbenzidine (TMB) used as the reporting dyeappears to interact with the magnetic beads to prevent DNA recovery. Hydrogen peroxide does not seem to be involved. The Hemastix® chemistriesdo not interfere in any way with DNA extraction performed using phenol-chloroform. The incompatibility of the Hemastix® chemistries on the DNAIQTMsystem forced us to adopt an indirect approach using filter paper to carry out the presumptive test
