D.A.B.-(DIAMINOBENZIDINE)

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Chemical Name:
D.A.B.-(DIAMINOBENZIDINE)
Surface Used On:
Blood-stained porous & non-porous surfaces.
Sensitive To:
Blood Proteins
Development Color: Method to Record: Hazard: Protective Clothing: Fume Hood Use:

Brown

Yes
Reagent Characteristics

Development Complete When:

Source of Error:

Incompatibilities:

Precautions:

Storage Container:

Safety:

Recommendations:


Similar Reagents



Sequential Reagents
(Not necessarily in this order.)



Abridged Reagent Sequence


Visual Examination
|
Forensic Light
|
Ultra-violet light
|
*** D.A.B. ***
|
Forensic Light
|
Amido black

D.A.B.-(DIAMINOBENZIDINE) FORMULA:
1.   (Solution A)
20g 5-Sulfosalicylic Acid
dissolved in 1L distilled water


2.   (Solution B)
100ml 1N phosphate buffer(Ph 7.4)
Mixed in 800ml distilled water

3.   (Solution C)
1g DAB dissolved in 
100ml distilled water

4.   (Working Solution)
180ml Solution B
20ml Solution C
add 1ml 30% Hydrogen peroxide

PROCEDURE OF APPLICATION
1. Solution A fixation
   2-3 minutes, then water rinse.

2a. Tray immersion of item
into working solution for
3 to 4 minutes.
    
     -- or --
 
2b. Filter paper saturation of
working solution for 3 minutes.

3. Distilled water rinse.


Ridge Detail Visualized by:

Visible chemical/stain reaction.


Reagent Applicabilities:

Porous surfaces
Non-Porous surfaces
Blood Enhancement


Other Chemical Name(s):

3,3'-Diaminobenzidine tetrahydrochloride


Working Solution Shelf-life:

48 hours if refrigerated.

Process Summary:
DAB undergoes an oxidation reaction, catalyzed by the heme groups in hemoglobin, in the presence of hydrogen peroxide, which produces the dark brown color reaction. A peroxidase reagent which is colorless, but becomes strongly visible when reacted with blood. May be used in conjunction with Amido Black and ABTS. Good results achieved on some paper items. Ninhydrin has no effect on the D.A.B. process. Other blood enhancement colored protein stains may be used after D.A.B. Cyanoacrylate fuming is detrimental to D.A.B. processing.
Accepted Deviations:
D.A.B. can be applied in two general manners - by immersing the item in a D.A.B. solution, or, by a "Paper Blotting" method.
Supporting Reference Materials:
1. Sahs, P., "DAB: An Advancement in Blood Print Detection", J. Forensic. Ident., Vol. 42., No. 5,(1992), pg 412.
2. Slater, J., "Techniques for the Enhancement of 2-Dimensional Footwear Impressions in Blood", Forensic Services Div., May, 1995.
3. "Chemical Formulas and Processing Guide for Developing Latent Prints", U.S. Dept. of Justice, FBI Laboratory, pg. 23, 1994.
4. "ABTS: A Safe Alternative to DAB for the Enhancement of Blood Fingerprints", Caldwell, J.P., Henderson, W., Kim, N.D., Jor. Forensic Sciences, Vol. 45, No. 4, July 2000, pp. 785-794.
5. Minutiae Magazine, Summer Special 1994, Issue No. 24, pg.7.

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