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- Title
Phenolphthalein False-Positive Reactions from Legume Root Nodules.
- Authors
Petersen, Daniel; Kovacs, Frank
- Abstract
Presumptive tests for blood play a critical role in the examination of physical evidence and in the determination of subsequent analysis. The catalytic power of hemoglobin allows colorimetric reactions employing phenolphthalein ( Kastle- Meyer test) to indicate 'whether' blood is present. Consequently, DNA profiles extracted from phenolphthalein-positive stains are presumed to be from blood on the evidentiary item and can lead to the identification of 'whose' blood is present. Crushed nodules from a variety of legumes yielded phenolphthalein false-positive reactions that were indistinguishable from true bloodstains both in color quality and in developmental time frame. Clothing and other materials stained by nodules also yielded phenolphthalein false-positive reactivity for several years after nodule exposure. Nodules from leguminous plants contain a protein (leghemoglobin) which is structurally and functionally similar to hemoglobin. Testing of purified leghemoglobin confirmed this protein as a source of phenolphthalein reactivity. A scenario is presented showing how the presence of leghemoglobin from nodule staining can mislead investigators.
- Subjects
PRESUMPTIVE blood tests (Forensic chemistry); PHENOLPHTHALEIN; HEMOGLOBIN genetics; COLORIMETRIC analysis; LEGHEMOGLOBIN; NUCLEIC acid isolation methods
- Publication
Journal of Forensic Sciences, 2014, Vol 59, Issue 2, p481
- ISSN
0022-1198
- Publication type
Article
- DOI
10.1111/1556-4029.12352