D.F.O.

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Chemical Name:
D.F.O.		 Surface Used On:
Dry porous documents.		 Sensitive To:
Amino acids and eccrine components.
Development Color: Method to Record: Hazard: Protective Clothing: Fume Hood Use:

Yellow fluorescence.
Orange filter.
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
|
*** D.F.O. ***
|
Ninhydrin
|
Physical Developer

 D.F.O. FORMULA:

*** D.F.O. STOCK SOLUTION ***

  1 gram D.F.O. crystals
200 ml   Methanol
200 ml   Ethyl Acetate
 40 ml   Glacial Acetic acid

Combine and stir with a magnetic stirrer
until ALL the ingredients are dissolved. 



*** D.F.O. WORKING SOLUTION ***

Add Petroleum ether to the stock 
solution until the total volume 
is two liters.




*** IRCG FORMULATON ***

    .25 g DFO
 40 ml methanol
 20 ml acetic acid
940 ml HFE-7100
PROCEDURE OF APPLICATION 
1.
Submerge or spray the item - 5 seconds.

2.
Air-dry the item in a fume hood.

3.
Process the item a second time &
Air-dry the item in a fume hood.

4.
Oven bake @ 50 to 100 degrees C
for 10 to 20 minutes.

5.
View under a forensic light source
at 495 nm to 550 nm.
	
Absorption Max is 514 nm.  
View under orange or red barrier filters.


6.
Photograph results using a orange colored
or 550(BP 35)bandpass filter.


Ridge Detail Visualized by:

Forensic Light Source induced.


Reagent Applicabilities:

Porous sufaces
Fluorescent technique
Raw Wood surface


Other Chemical Name(s):

1,8-Diazafluoren-9-one


Working Solution Shelf-life:

Six (6) plus months.
Process Summary:
A technique used prior to Ninhydrin that reacts to amino acids present in latent print residue on porous surfaces. DFO is regarded as capable of developing more ridge detail than Ninhydrin. A fluorescence of the prints is obtained after baking the item in an oven at 100 degrees C, then viewing under a forensic light source.
Accepted Deviations:
A hair dryer or a DRY steam iron may be substituted for a baking oven, if necessary. Do not allow steam to contact the item. Strict control of the humidity is not required. Pentane (instead of Petroleum ether) can be used as the carrier solvent. View the item at 500 nm to 590 nm using red colored goggles to reduce background fluorescence, if necessary.
Supporting Reference Materials:
1. Minutiae Magazine, Summer Special 1994, Issue No. 24, pg.7.
2. "Chemical Formulas and Processing Guide for Developing Latent Prints", U.S. Dept. of Justice, pg. 47-48, 1994.
3. Advances in Fingeprint Technology 2nd. Ed., Lee, H.C. & Gaensslen, R.E., CRC Press, Boca Raton, FL., 2001.
4. Manual of Fingerprint Development Techniques 2nd. Ed., Home Office - Police Scientific Development Branch, White Crescent Press, Ltd., Luton, England, 2001.
5. Technical Notes, Lightning Powder Co. Inc., Salem, OR., 2001.
6. Didierjean, C., Debart, M-H, Crispino, F., "New Formulation of DFO in HFE-7100", Fingerprint Whorld, Vol. 24, No. 94, October 1998, pp.163-167.

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