Laboratory of Forensic Services
Serology Manual
Sacramento County District Attorney
SER: Saliva – Amylase Filter Paper Overlay
Amylase is an enzyme present in saliva at high concentrations and in other
body fluids (such as semen, vaginal fluid, urine) at low concentrations.
Amylase hydrolyzes starch.
Principle
This procedure is a presumptive test for saliva and determines whether
amylase is present in a stain.
This procedure uses the following laboratory equipment and supplies:
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Equipment and
supplies
 moisture chamber
 oven
 filter paper
 spray bottle
This procedure uses the following reagents:
Reagents
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 Stock iodine solution
 1.65 g potassium iodide
 2.5 g iodine
 Dissolve in 30 mL warm deionized water and filter.
 Working iodine solution
 Mix 1 milliliter of the Stock iodine solution with 99 mL of deionized
water.
 Starch Solution
 Using heat, dissolve 1 gram of starch in 250 mL of deionized water.
Controls
The following controls must be run with each test:
 Positive control- previously prepared neat saliva standard preserved on
cotton
 Negative control- previously prepared saline preserved on cotton
Continued on next page
Title:
Approved by:
Issue Date:
SER: Saliva- Filter Paper Overlay
Laboratory Director
10/2011
Revision No:
Document Class:
1
LFS Policy/Procedure
All printed copies are uncontrolled. This document printed on 2/4/2015
Page 1 of 3
Laboratory of Forensic Services
Serology Manual
Sacramento County District Attorney
SER: Saliva – Amylase Filter Paper Overlay, Continued
Filter paper
preparation
Prepare the filter paper by saturating it with the Starch solution and allowing
it to dry.
Store treated filter paper in refrigerator at 5C.
Use the following procedure to perform amylase overlay
Step
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Mark seams or other reference points for orientation.
Remove the filter papers.
Place filter papers in a moisture chamber and incubate in an oven
at approximately 40C for about 1 hour.
Remove filter papers from moisture chamber and allow to air dry.
Spray the filter papers with the Working Iodine Solution until a
blue color develops.
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Action
Place cuttings of the positive and negative control on a glass or
plastic plate.
Spread out the evidence item to be analyzed.
Saturate filter papers for evidence item and controls with
deionized water.
Place the treated filter paper over item and a separate treated filter
paper on the controls.
Allow the filter papers to maintain good contact with the samples
for approximately 20 minutes.
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Procedure
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Continued on next page
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Title:
Approved by:
Issue Date:
SER: Saliva- Filter Paper Overlay
Laboratory Director
10/2011
Revision No:
Document Class:
1
LFS Policy/Procedure
All printed copies are uncontrolled. This document printed on 2/4/2015
Page 2 of 3
Laboratory of Forensic Services
Serology Manual
Sacramento County District Attorney
SER: Saliva – Amylase Filter Paper Overlay, Continued
Interpretation
Starch will react with the iodine solution and turn blue. If there is no starch in
an area, it will appear white.
A white area on the filter paper is a positive (+) result for the presence of
amylase.
The absence of white areas is a negative (-) result for the presence of amylase.
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Amylase is present in saliva at high concentrations. However, it is also
present in most tissues and body fluids, including semen, vaginal fluid, and
urine, at much lower levels. Since amylase is not unique to saliva, the
amylase overlay is a presumptive test only.
NOTE: To determine the approximate amount of amylase present, refer to
SER: Saliva- Radial Diffusion of Amylase in this manual.
References
The following references were used in the development of this procedure.
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Houde, J., “Saliva Mapping,” CACNews, Fall 1993, pg. 4.
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Forensic Examination of Sexual Assault Evidence (Section 25). California
Criminalistics Institute. 1992.
Title:
Approved by:
Issue Date:
SER: Saliva- Filter Paper Overlay
Laboratory Director
10/2011
Revision No:
Document Class:
1
LFS Policy/Procedure
All printed copies are uncontrolled. This document printed on 2/4/2015
Page 3 of 3