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A Comparison of Four Presumptive Tests for the Detection of Blood on Dark Materials
Author(s) -
Butler Julie,
Chaseling Janet,
Wright Kirsty
Publication year - 2019
Publication title -
journal of forensic sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.715
H-Index - 96
eISSN - 1556-4029
pISSN - 0022-1198
DOI - 10.1111/1556-4029.14091
Subject(s) - luminol , bleach , human blood , crystal violet , blood stains , whole blood , predictive value , chromatography , socks , medicine , chemistry , detection limit , surgery , materials science , pathology , composite material , physiology , organic chemistry
Abstract Detection of blood on dark materials is difficult for crime scene examiners so presumptive tests are used to assist. This study compared the ability of luminol, leuko crystal violet, tetramethylbenzidine, and Combur Test®E to detect whole, diluted blood (1:100) and a key‐shaped blood transfer stain (1:10), on dark cotton sheeting, tea towel, socks, synthetic carpet, and car mats. Powdered bleach was used to evaluate specificity of the blood detection tests. Sensitivity, specificity, positive predictive value ( PPV ), negative predictive value ( NPV ), and overall misclassification rate ( OMR ) assessed the quality of the blood tests. Luminol was the preferred test for diluted blood having the highest sensitivity (79%–96%), NPV (66%–93%), and the lowest OMR (3%–15%). Luminol was also found to be most efficient with a testing time on 25 items of 2 h 50 min compared with up to 8 h. Overall, luminol was the most effective method, also providing information on bloodstain patterns.