Acid Yellow 7

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Development Color:

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Method to Record:

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Hazard:

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Protective Clothing:

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Fume Hood Use:

Formula

Procedure of Application

Development Complete When

Source of Error

Incompatibilities

Precautions

Storage Container

Safety

Recommendations

Similar Reagent

Sequential Reagent

Formula

Acid Yellow 7 Pre-made Solution

4% Acid Yellow 7
84% Water
10% Acetic Acid
2% Formic Acid

Procedure of Application

Fixing the Blood Print - Fixing is not required, but is recommended. A solution of 5% 5-sulfo-salicylic acid would be misted (pump sprayer) over the enhancement area. After fixing, allow 15 minutes for the fixative to dry. When the blood is relatively fresh, you will notice that fixing changes its color from dark red to dark brown.
Staining the Blood Print - Once the print is fixed, it can be stained with Acid Yellow 7 Solution. Use the pump spray to mist the solution over the blood print. DO NOT SPRAY DIRECTLY AT PRINT, hover over the space being treated, spraying parallel to the surface. After spraying, allow the stain to set, usually 5-10 minutes.
Rinse the Print - After the stain has set, rinse the area to remove background. This can be done with water or white vinegar. If the print is on a horizontal surface, gently pour water across the stained print and use absorbent paper to carefully blot the residual dye away from the background.

Development Complete When

Prints will be yellow in color, but will fluoresce a bright yellow under alternate light sources in the blue to blue/green range of 455nm to 470nm. View with an orange barrier filter. Photograph with a comparable orange filter on the lens.

Source of Error

Prints wash away due to fixative not being applied.

Cyanoacrylate fuming may be detrimental to this reagent.
Excessively blood-stained items will obliterate detail.

Incompatibilities

Excessively blood-stained items and porous surfaces that strongly absorb the dye will yield little contrast to the developed detail.

Porous items will get destroyed by acid content in the solution and waxed items may get eaten away or destroyed as well.

Precautions

use in fume hood, wear gloves and goggles due to its potential to be a lung and eye irritant.

Storage Container

Store in Flammable cabinet in the bottle it comes in.

Safety

Fume hood is required to apply solution. Safety coat and goggles to be worn.

Recommendations

Fix blood prior to use.

Similar Reagent

Sequential Reagent

None.

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Chemical Name
Acid Yellow 7
Surface Used On
Blood-stained Non-porous Surfaces
Sensitive To
Blood Proteins
Abridged Reagent Sequence

Visual Examination
Forensic Light/UV light
5% Sulfosalicylic Acid (Blood Fixative)
Acid Yellow 7
Forensic Light

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Ridge Detail Visualized by:
Blue/Green Light with Orange Filter (455nm-470nm)

Reagent Applicabilities:
Non-Porous Surfaces
Blood Enhancement

Other Chemical Name(s):
N/A

Working Solution Shelf-life:
1 year from opening, unless otherwise indicated by manufacturer

Process Summary:
A dye staining process preceded by a blood fixative (5% Sulfosalicylic Acid), that is used to enhance detail in faint bloody impressions.

Accepted Deviations:
Blood fixative not required if the premade Acid Yellow 7 contains 5% Sulfosalicylic Acid.

Supporting Reference Materials:

Enotes.com Inc. World of Forensic Science/Alternate Light Source Analysis, <http://www.enotes.com/forensic-science/alternate-light-source-analysis>. February 7, 2011
Sears, V.G.; Butcher, C.P.G.; Fitzgerald, L.A. "Enhancement of Fingerprints in Blood, Part 3: Reactive Techniques, Acid Yellow 7, and Process Sequences." Journal of Forensic Identification 2005, Vol. 55, No. 6, p. 741-763