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EnglishIdentification of saliva on stamps or envelope flaps remains yet a not widely studied problem. In most forensic laboratories it is seldom carried out, but this fact does not reduce the importance of the assay. Most authors consider amylase a sufficiently specific marker of the presence of saliva; really, the only other human body fluid that contains high amounts of this enzyme is the pancreatic juice (and therefore feces). Here we present a simple and sensitive assay for the determination of alpha-amylase that uses a commercially available and well-known substrate. It is hydrolyzed by amylase with the production of soluble blue fragments, that can be measured by photometry, obtaining objective results. The presented assay identifies 1 X 10(-6) diluted saliva or that present on 0.5 mg of a stamp; 16-year-old samples can also be identified. Intra-assay and day-to-day CV resulted in 10.8% and 13.7%, respectively. Owing to the high sensitivity of the test, handling samples or reagents can introduce contamination with saliva traces, giving false-positive results. Addition of EDTA 0.1 mol/l to the incubation mixture, lowering the sensitivity to 1 X 10(-3) diluted saliva, overcomes this problem.
| Titolo: | A sensitive and simple assay of saliva on stamps |
| Autori: | |
| Data di pubblicazione: | 1985 |
| Rivista: | |
| Abstract: | Identification of saliva on stamps or envelope flaps remains yet a not widely studied problem. In most forensic laboratories it is seldom carried out, but this fact does not reduce the importance of the assay. Most authors consider amylase a sufficiently specific marker of the presence of saliva; really, the only other human body fluid that contains high amounts of this enzyme is the pancreatic juice (and therefore feces). Here we present a simple and sensitive assay for the determination of alpha-amylase that uses a commercially available and well-known substrate. It is hydrolyzed by amylase with the production of soluble blue fragments, that can be measured by photometry, obtaining objective results. The presented assay identifies 1 X 10(-6) diluted saliva or that present on 0.5 mg of a stamp; 16-year-old samples can also be identified. Intra-assay and day-to-day CV resulted in 10.8% and 13.7%, respectively. Owing to the high sensitivity of the test, handling samples or reagents can introduce contamination with saliva traces, giving false-positive results. Addition of EDTA 0.1 mol/l to the incubation mixture, lowering the sensitivity to 1 X 10(-3) diluted saliva, overcomes this problem. |
| Handle: | http://hdl.handle.net/11562/6987 |
| Appare nelle tipologie: | 01.01 Articolo in Rivista |
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