Comparison of chemiluminescent and fluorescent blood detection kits
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Citation
Abstract
Blood at a crime scene is not always detected by the naked eye, and hence requires the use
of special reagents and alternate light sources. Two of these reagents – luminol and
fluorescein – have been in use in forensic science both in their original forms and in the
form of commercially produced reagents, Bluestar® and Hemascein™. The manufacturer
of Hemascein™, the relatively newer product, states that the reagent exhibits lower
amounts of cross-reactivity with bleach and is less detrimental to DNA as compared to
Bluestar®. They also say that the reagent does not require complete darkness to function,
unlike Bluestar®. These parameters, along with the impact of Bluestar® and Hemascein™
on pattern detail, were evaluated in this study. It was found that both reagents exhibited
some positive reactions with bleach; however, Bluestar® had a less intense reaction with
lower concentrations of bleach, while Hemascein™ showed a lower intensity for cross
reactions with higher concentrations. A distinct difference was observed for the reagents
with respect to retention of pattern characteristics in bloodstains, with Hemascein™
causing considerable diffusion of the pattern. The results also demonstrated that there was
a dependence of the color of the substrate on the performance of Hemascein™, with lighter
colored substrates far outperforming their darker counterparts. Hemascein™ performed
better than Bluestar® in well-lit conditions, with a positive luminescent reaction observed
in ambient lighting conditions. Additionally, neither of the reagents showed inhibition
during quantitative PCR, thus deeming them both appropriate for use when subsequent
recovery of DNA is desired. There were differences in the amounts of DNA recovered
from the treated blood samples, however, further studies and a larger sample size would be
required to determine if these variations are related to the application of Bluestar® and
Hemascein™. All DNA recovered was sufficient in quantity to expect successful DNA
profiling if such analysis had been carried out.