Technical Note

Ardrox Fluorescent Dye

Introduction

Ardrox is a highly fluorescent dye stain which stains cyanoacrylate-developed latent prints. When illuminated with an ultraviolet lamp or Forensic Light Source, latent prints fluoresce brightly, and weakly-developed latent prints that could not be seen under normal viewing conditions may be easily seen and photographed. Because Ardrox is very sensitive to ultraviolet light, it can be used by police agencies that cannot afford to purchase a more expensive Forensic Light Source.

Safety

As with all chemicals, always read the MSDS (material safety data sheet) to learn about the safe handling and health hazards of each chemical. With Ardrox, it is recommended that rubber gloves and safety glasses be worn. When combined with any of the solvents listed below, the solution should be mixed and used in a fume hood. When examining the evidence with a light source, wear protective goggles. Be familiar with the light source and know which goggles to wear under all circumstances.

Mixing Instructions

Ardrox is a thick, yellow liquid. It is recommended that it be diluted before using. The simplest dilution is 2% Ardrox in methanol. In other words, 2 ml of Ardrox in 100 ml of methanol. This dilution can be adjusted to make it stronger (add another 1 to 2 ml of Ardrox) or to make it weaker (only add 1 ml of Ardrox to 100 ml of methanol). Another suggested alternative solution is to add 1 ml of Ardrox to 95 ml of isopropyl alcohol (2-propanol) and add 5 ml acetronitrile.

Glue Fuming

Before using Ardrox, it is necessary to glue-fume the piece of evidence. It is recommended to underfume rather than overfume. If heavy white residue is present on the background surface or heavy white latent prints are developed, the Ardrox may stain the entire surface and the latent prints will appear as bright glowing globs with no ridge detail when illuminated with a light source. The use of fast-acting, chemical catalysts or accelerator pads is not recommended, as the process can develop heavy, white residue before the reaction can be stopped.

Place a few drops of liquid glue or a Hard Evidence™ Pouch in a closed container, such as a fish tank, with the evidence and a cup of warm water. Allow the evidence to remain about ten minutes before checking. To check the progress of the fuming without opening the lid of the fish tank, place a black latent print backing card in the tank with test prints on it. When these test prints are just becoming visible, remove the evidence from the tank to stop the process. Fuming under vacuum with a Coleman Vacu-Print™ will help to eliminate the problems associated with overfuming. Vacuum technology for glue fuming is relatively new. This method will develop latent prints without excessive residue coating the surface of the evidence, and it will be easier to handle the evidence.

Because there is no residue buildup on the evidence, dye-staining for fluorescent examination is more effective. Dyes such as Rhodamine 6G and Ardrox adhere to the glue residue on the item. When there is excessive buildup of the glue residue, the dye stains all of it, causing the entire surface to fluoresce, perhaps obscuring ridge detail. With a vacuum process, items of evidence, such as garbage bags do not have to be opened up. The fumes will coat all of the surfaces. Also, items such as soda cans, screwdrivers and handguns can be placed inside the chamber with the items touching each other. It is not necessary to leave space between each item. For additional information on the Coleman Vacu-Print™ vacuum fuming chamber and glue fuming processes, see the Coleman Vacu-Print and Glue Fuming tech notes.

Application

In a fume hood, apply the Ardrox solution by submerging the evidence in a tray or container. "Washing" the solution over the surface using a chemical wash bottle can also be done, but it is not as effective as soaking. Catch the runoff solution in a clean tray and use it again. DO NOT SPRAY THIS SOLUTION. A one- to three-minute soaking in the Ardrox solution should be long enough. Rinse the item with running tap water. Allow the item to air-dry before examining with a light source.

An alternative rinse solution may consist of 10 ml of acetic acid in 100 ml of methanol. This may be more effective in rinsing the excess residue from the background without damaging the latent prints. As before, allow the item to air-dry before examining with a light source.

Examination

Dim the room lights and shine the light from the Forensic Light Source or ultraviolet lamp over the surface of the object. A long-wavelength ultraviolet lamp with a moderate to high intensity output can be used effectively to illuminate latent prints developed with Ardrox. Photograph the visualized latent prints. For those using a variable wavelength Forensic Light Source, examine the evidence using 450 to 480 nm light and view with orange goggles. Also, examine the evidence with 365 nm wavelength of light.

Photography

To photograph the fluorescent-developed latent prints, duplicate the arrangement by which the best contrast was viewed with the eye. Use the wavelength, the color of viewing goggles and the angle of the light source to obtain the best photograph. Include a fluorescent scale in the photograph. Using a fine-grain black and white film with a medium ƒ-stop (ƒ/8 or ƒ/11) will give a photograph showing highly defined ridge details. The ridges will be white and the background will be dark in the resulting photograph.

To reverse the color of fluorescent-developed latent prints, take the photographs using slide film, such as Polaroid PolaPan, to see the results in just a few minutes. Print the slide film on regular black and white photo paper to see the ridges dark and the background light. For additional information on photography of fluorescent latent prints, see our fluorescent photography technical note.

Additional Reading

Advances in Fingerprint Technology edited by Dr. Henry Lee and Dr. R. E. Gaensslen
Fingerprint Detection by Fluorescence Examination by the British Home Office
An Introduction to Lasers, Forensic Lights and Fluorescent Fingerprint Detection Techniques by Dr. E. Roland Menzel

Ordering Information

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