Sensitivity and specificity of presumptive tests for blood, saliva and semen.
OBJECTIVE
Despite their wide use, the limits of presumptive tests can be poorly understood. The aim of this study was to investigate the specificity and sensitivity of conventional, as well as innovative, presumptive tests for blood, semen and saliva.


METHODS
We investigated Kastle-Meyer (KM) and leucomalachite green (LMG) tests for blood with regard to their sensitivity and specificity in the presence of oxidizing (hypochlorite) and anti-oxidizing (ascorbic acid) agents. The suitability and specificity of the red starch paper (RSP) test for saliva was assessed. Finally, the inhibitory effect of detergent on the acid phosphatase (AP) test for semen was investigated along with possible cross reactions to tea stains.


RESULTS
Our results confirm previous findings of higher sensitivity and specificity of the KM test compared to LMG test for blood. Contrary to previous studies, no statistically significant difference was observed in the sensitivity of the tests between dry and wet stains. The novel RSP test was found to successfully detect saliva. We demonstrated that acid phosphatase (AP) testing for semen is possible on used RSP. A common multipurpose detergent had an inhibitory effect on AP tests. False positive results were obtained from tea stains. Testing different sorts of tea (black, green and herbal teas) revealed that only Camellia varieties produce positive result with the AP test, due to AP being present in the plants.


CONCLUSIONS
From our results we conclude that specific knowledge of each test, including substances that may affect the test outcome, is imperative to ensure correct interpretation of presumptive test results.
Department of Pure and Applied Chemistry, Centre for Forensic Science, University of Strathclyde, 204 George Street, Glasgow, G1 1XW, UK, marielle.vennemann@ukmuenster.de.
Marielle
M
Vennemann
Georgina
G
Scott
Lynn
L
Curran
Felix
F
Bittner
Shanan S
SS
Tobe
D000135:Acid Phosphatase / Q000032:analysis; D000818:Animals; D016477:Artifacts; D015415:Biomarkers / Q000097:blood; D001769:Blood; D001774:Blood Chemical Analysis; D028244:Camellia; D002417:Cattle; D004396:Coloring Agents; D003902:Detergents / Q000737:chemistry; D005189:False Positive Reactions; D006801:Humans; D008297:Male; D010084:Oxidation-Reduction; D028321:Plant Preparations / Q000737:chemistry; D011237:Predictive Value of Tests; D012394:Rosaniline Dyes; D012463:Saliva / Q000737:chemistry*; D012661:Semen / Q000737:chemistry*; D055101:Semen Analysis; D013048:Specimen Handling; D000516:alpha-Amylases / Q000032:analysis
D015415:Biomarkers; D004396:Coloring Agents; D003902:Detergents; D028321:Plant Preparations; D012394:Rosaniline Dyes; C015320:leucomalachite green; D000135:Acid Phosphatase; D000516:alpha-Amylases