OIL RED O

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Chemical Name:
OIL RED O		 Surface Used On:
Wet, Porous items.		 Sensitive To:
Lipid components.
Development Color: Method to Record: Hazard: Protective Clothing: Fume Hood Use:

Red
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
|
*** Oil Red O ***
|
Physical Developer

 OIL RED O FORMULA:
       STAIN SOLUTION

  1.54 g  Oil Red O powder
dissolved in 770 ml Methanol

  9.2 g Sodium hydroxide
dissolved in 230 ml distilled water

  Add the Sodium hydroxide solution
to the Oil Red O solution.

  Mix & filter the combined 
solutions. Store in a dark bottle.


       PHOSPHATE ph7 BUFFER SOLUTION

  101.55 g Sodium phosphate monobasic monohydrate
dissolved in 1 L distilled water

  338.79 g Sodium phosphate dibasic heptahydrate
dissolved in 1 L distilled water
 
Shake both solutions until dissolved, then combine.

  Add distilled water to increase the combined 
buffer solutions volume to 4 L.


            ( Alternative )       
	CARBONATE ph7 BUFFER SOLUTION

  26.5 g Sodium carbonate
dissolved in 2 L distilled water

  Add (carefully) 18.3 ml 
concentrated Nitric acid.
Shaking constantly.

  Add distilled water to increase
the buffer solution volume to 2.5 L.
PROCEDURE OF APPLICATION 

1. Immerse the item in stain solution 
and soak completely.  It is optional to 
agitate the solution on a shaker platform. 


 - Ridge detail should begin to develop in 5 min.
 - Weak fingerprints (poor lipidic content) may 
   require 60 to 90 minutes of development time.	

2. Remove & drain item - immerse in 
one of the buffer solutions.

3. Remove item from buffer solution - 
rinse in distilled water.

4.  Dry item at room temperature - 
or heat in an oven at 50 degrees C.


Ridge Detail Visualized by:

Visible chemical/stain reaction.


Reagent Applicabilities:

Water-soaked items
Porous sufaces
Lipid-sensitive reagent


Other Chemical Name(s):





Working Solution Shelf-life:

Stain Solution - indefinite, providing its methanol does not dissolve.

Carbonate Buffer solution - 3 to 4 months.

Phosphate Buffer solution - approx. 8 to 12 months.
Process Summary:
A lipid-specific dye stain technique for use on porous items which have become wet. Research has shown that Oil Red O can be superior to Physical Developer to develop latent fingerprints on thermal paper and standard white paper. Fewer immersion steps and less need to avoid chloride contamination are benefits using the Oil Red O reagent.
Accepted Deviations:
The Carbonate pH7 buffer solution may be used instead of the Phosphate pH7 buffer solution.

Oil Red O may be used as a precursor to Physical developer to locate areas of likely friction ridge detail on brown kraft paper. Physical developer treatment follows Oil Red O in order to improve the resolution of the friction ridge detail.
Supporting Reference Materials:
1. Beaudoin, A., "New Technique for Revealing Latent Fingerprints on Wet Porous Surfaces: Oil Red O", Jor. For. Ident., Vol. 54, No. 4, July 2004, pg. 413-421.
2. Rawji, A. & Beaudoin, A., "Oil Red O Versus Physical Developer on Wet Papers: A Comparative Study". Jor For. Ident., Vol. 56, No. 1, Jan 2006, pg. 33-54.
3. Horobin, R. & Kiernan, J., Eds. Conn's Biological Stains", 10th. ed., Springer-Verlag, New York, 2002.

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