A comparison of the presumptive luminol test for blood with four non‐chemiluminescent forensic techniques

Abstract

Presumptive blood detection tests are used by forensic investigators to detect trace amounts of blood or to investigate suspicious stains. Through the years, a number of articles have been published on the popular techniques of the day. However, there is no single paper that critiques and compares the five most common presumptive blood detection tests currently in use: luminol, phenolphthalein (Kastle-Meyer), leucomalachite green, Hemastix and the forensic light source. The present authors aimed to compare the above techniques with regard to their sensitivity, ease of use and safety. The luminol test was determined to be the most sensitive of the techniques, while Hemastix is a suitable alternative when the luminol test is not appropriate.

The application of imaging technologies in the detection of trace evidence in forensic medical investigation

“…[15] The best general wavelength and goggle combination for detecting biological stains is 450nm with orange goggles. [16][17] It does not pose any known harmful effects to the user except when operated in the UV range [18] or when the high intensity beam is looked upon without the provided protective eyewear [16] and it is deemed a safe, simple, non-invasive and non-destructive tool for the screening of scenes and exhibits. [19] Most studies using Alternative Light Source systems focus on inert substrates which limits its applicability to the examination of human skin.…”

Body fluid identification in forensics

“…Although false-positives are reported in the presence of chemical oxidants and vegetable peroxidases, the test can detect blood as dilute as 1 part in 10,000. In addition, this test is nondestructive to the sample, which can then be kept and used in further tests, including DNA analysis (20,21,24,25).…”

Chemical Sensing and Detection in Forensic Science

“…It can also disclose the distribution, allowing bloodstain pattern evaluation and occasionally enabling the investigators to reconstruct some of the events of a crime by visualizing these patterns [41,42]. Compared to other chemical-based tests and physical techniques for the detection of blood at crime scenes, luminol has the advantage of high sensitivity [43][44][45], with one evaluation reporting that the luminol test could detect blood to a dilution of 1:1,00,000 [46]. In addition, the luminol test does not significantly damage genetic material, especially when modern polymerase chain reaction (PCR) techniques are employed to analyze microsatellite DNA.…”

“…One operational advantage of the luminol test is the ability to highlight the presence of scattered, very small droplets of blood by the individual "sparkles" of blue chemiluminescence produced by each droplet. This makes this test easier to interpret then the other three common presumptive tests for blood (the benzidine, phenolphthalein, and leucomalachite chromogen tests) [43,51].…”