The acid phosphatase test two minute cut-off: An insufficient time to detect some semen stains

Redhead, Paul; Brown, Melanie K.

doi:10.1016/j.scijus.2012.09.004

Cited by 16 publications

(5 citation statements)

References 12 publications

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“…The forensic science community has historically relied on the AP reaction as the best indicator for the presence of sperm. Following a literature search, Lewis reported no scientific basis for the two‐minute AP cutoff time, and additionally, both Lewis and Redhead demonstrated that increasing this cutoff time up to 16 min may be required in certain scenarios. Hofft states that the AP test does not provide reliable information as to the presence of seminal fluid and it is very tenuously related to the number of sperm heads.…”

Section: Discussionmentioning

confidence: 99%

The Persistence of Sperm and the Development of Time Since Intercourse (TSI) Guidelines in Sexual Assault Cases at Forensic Science Ireland, Dublin, Ireland

Casey

Domijan

MacNeill

et al. 2016

Journal of Forensic Sciences

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The persistence of sperm using confirmatory microscopic analysis, the persistence of sperm with tails, time since intercourse (TSI) analysis, and results from the acid phosphatase (AP) reaction from approximately 5581 swabs taken from circa 1450 sexual assault cases are presented. The observed proportions of sperm in the vagina and anus declines significantly after 48 h TSI, and sperm on oral swabs were observed up to 15 h TSI. The AP reaction as a predictor of sperm on intimate swabs is questioned. All AP reaction times gave a low true positive rate; 23% of sperm-positive swabs gave a negative AP reaction time. We show the AP reaction is an unsafe and an unreliable predictor of sperm on intimate swabs. We propose that TSI not AP informs precase assessment and the evaluative approach for sexual assault cases. To help inform an evaluative approach, TSI guidelines are presented.

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Section: Discussionmentioning

confidence: 99%

The Persistence of Sperm and the Development of Time Since Intercourse (TSI) Guidelines in Sexual Assault Cases at Forensic Science Ireland, Dublin, Ireland

Casey

Domijan

MacNeill

et al. 2016

Journal of Forensic Sciences

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“…The results of the AP Spot Test on semen dilutions suggest that samples that contain low amounts of AP can take more time to show a positive reaction, and it could possibly take longer than two minutes. Other literature researchers show the same conclusion, indicating that the two minutes estimated to avoid false-positive results have no scientific basis [7,8]. Therefore samples which take more than two minutes to react should not be considered false-positive and promptly discarded as evidence, since there may be seen in low concentrations.…”

Section: Discussionmentioning

confidence: 83%

Comparison of the sensitivity and specificity of colorimetric and immunochromatographic presumptive methods for forensic semen detection

Gonçalves

Oliveira

Carvalho

et al. 2017

Forensic Science International: Genetics Supplement Series

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“…However, as the method is currently implemented by operational forensic science laboratories allows 2 min for a reaction to be obtained beyond which a negative result is declared (Skalleberg and Bouzga 2016). Furthermore, recent research has shown that using the AP standard presumptive test semen could be detected in excess of 15 min depending on the dilutions using the press and test method (Lewis et al 2012;Redhead and Brown 2013). The proposed substitute method falls within the timeframe that is indicated by standard operational forensic science laboratories.…”

Section: Discussionmentioning

confidence: 95%

A Substitute Presumptive Test for Screening of Semen using Sodium –p– Nitrophenyl Phosphate (NaPNPP)

Njau

Lunayo

Odour

2021

Preprint

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BackgroundIn forensic investigation of alleged sexual crimes, presumptive semen detection test methods are commonly used to reach preliminary identification of seminal fluid in questioned samples. These methods are based on the detection of components of semen such as enzyme acid phosphatase (AP). Of these methods, the acid phosphatase identification method still remains the most reliable and widely used presumptive test due to high activity of the AP in seminal fluid. In standard AP test, Bretamine Fast Blue B (FBB) reagent is used. However FBB has been explicitly classified as carcinogenic. Although FBB has been handled safely over time, there is a need at the moment to develop a simple, readily available, reliable and efficient method for screening the presence of semen in any material collected as evidence in a sexual assault crime.Given the improved sensitivity of DNA profiling tests that have been introduced in to routine forensic casework over recent years, the need for improved sensitivity at this first stage of detection has never been higher. FindingsHere we highlight a simple method using readily available reagents in standard biochemical laboratory as a substitute for the standard AP test for seminal fluid identification from a crime scene. This method is based on the hydrolysis of sodium–p-nitrophenyl phosphate at pH 5.5 by the acid phosphatase to produce an intense yellow coloured complex in 15 seconds. ConclusionsThe method presented is sensitive, reliable, efficient and routinely used in standard biochemical and pathology laboratories for spectrophotometric analysis of alkaline phosphatase. It can be easily and readily applied as a preliminary test for identification of semen at a crime scene that involves sexual assault.

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The acid phosphatase test two minute cut-off: An insufficient time to detect some semen stains

Cited by 16 publications

References 12 publications

The Persistence of Sperm and the Development of Time Since Intercourse (TSI) Guidelines in Sexual Assault Cases at Forensic Science Ireland, Dublin, Ireland

The Persistence of Sperm and the Development of Time Since Intercourse (TSI) Guidelines in Sexual Assault Cases at Forensic Science Ireland, Dublin, Ireland

Comparison of the sensitivity and specificity of colorimetric and immunochromatographic presumptive methods for forensic semen detection

A Substitute Presumptive Test for Screening of Semen using Sodium –p– Nitrophenyl Phosphate (NaPNPP)

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