title: Bloodstains on Leather: Examination of False Negatives in Presumptive Test and Human Hemoglobin Test.
abstract: Presumptive tests for blood are very simple and sensitive tests used in the search for evidence. They also provide initial information on the nature of stains. A second test can confirm their nature. However, these tests can present false-negative results for different reasons. Some of those reasons have been studied, while others, those caused by the substrate material that contains the stain, are less well known. This work studies the effect of one component of a leather substrate-quebracho extract-on presumptive and human hemoglobin blood tests. Assays were performed using samples of blood dilutions contaminated with quebracho extract and others formed on a substrate containing the contaminant. Results show an undoubted interference that causes false negatives and even visible to the naked eye stains and also indicate that some tests (phenolphthalein) are more affected than others. Examiners should be taken into account when working on this kind of substrates.
authors.affiliation: Professor of Legal Medicine, University of Valencia EG, Facultad de Medicina, U. D. Medicina Legal, Valencia, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Castelló
authors.affiliation: Professor of Legal Medicine, University of Valencia EG, Facultad de Medicina, U. D. Medicina Legal, Valencia, Spain.
authors.forename: Francesc
authors.initials: F
authors.lastname: Francès
authors.affiliation: Professor of Legal Medicine, University of Valencia EG, Facultad de Medicina, U. D. Medicina Legal, Valencia, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Verdú
mesh_terms: D001774:Blood Chemical Analysis; D001801:Blood Stains; D002846:Chromatography, Affinity; D005189:False Positive Reactions; D044707:Forensic Sciences; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D007202:Indicators and Reagents; D013634:Tannins
chemical_list: D006454:Hemoglobins; D007202:Indicators and Reagents; D013634:Tannins
keywords: bloodstain analysis; false-negative results; forensic biology; forensic science; human hemoglobin test; presumptive test