Liqui-Drox is a fluorescent dye solution specifically designed to develop latent fingerprints on the adhesive side of dark-colored tapes. The active ingredient in Liqui-Drox is Ardrox, a commercially available fluorescent dye used in various industrial applications. Its key advantage lies in its ability to readily penetrate the fingerprint residue left on a tape's adhesive. Ardrox strongly fluoresces under long-wave ultraviolet (UV) light, making the developed latent prints stand out clearly against the dark background.
Equipment
- Fume Hood: Safety first! Working with Liqui-Drox necessitates a fume hood for proper ventilation.
- Glass Beakers or Jars: For preparing and storing your Liqui-Drox solution.
- Stirring Rod: A glass or inert stirring rod for mixing the solution.
- Gloves: Nitrile or latex gloves to protect your hands.
- Safety Glasses: Eye protection is a must when working with chemicals.
- Forensic Light Source or UV Lamp: A handheld UV lamp or an alternate light source (ALS) with the appropriate wavelength (around 365nm to 500nm).
- Protective Goggles (Orange or Yellow): These filter out ambient UV while allowing you to see the fluorescent prints.
- Camel Hair Brush: A soft brush for applying Liqui-Drox.
- Shallow Tray: For rinsing the processed tape.
Ingredients and Quantities: 1-Liter Solution of Liqui-Drox
- Ardrox P-133D: 1 gram
- Liqui-Nox (or similar dishwashing detergent): 10 milliliters
- Distilled Water: Approximately 1 liter
Mixing Procedure
- Safety First: Don your gloves and safety glasses. Work within your fume hood.
- Prepare Solution: In your beaker or jar, add about 900 ml of distilled water.
- Add Liqui-Nox: Measure out your Liqui-Nox detergent and gently add it to the water while stirring continuously.
- Add Ardrox: Carefully measure out the Ardrox P-133D and add it to the solution, stirring constantly until fully dissolved.
- Top Off: Slowly add more distilled water to reach the final 1-liter volume mark. Keep stirring gently for a homogenous solution.
Latent Print Processing Using Liqui-Drox
- Visual Examination: Start with a thorough examination of the tape under normal and alternate lighting conditions for any visible prints.
- Application: Using your camel hair brush, apply Liqui-Drox gently to both sides of the tape, working until a lather forms.
- Wait: Let the reagent sit for about 10 seconds.
- Rinse: Under a gentle stream of cold tap water, rinse off the excess Liqui-Drox from the tape.
- Dry: Allow the tape to air dry completely.
- Visualization: Examine the tape under your UV light source while wearing your protective goggles. Developed latent prints will fluoresce brightly.
- Photography: Document any developed prints immediately with a camera using an ultraviolet blocking filter (like a 2A filter).
Storage Requirements
- Light Protection: Liqui-Drox is light-sensitive. Store it in an opaque, preferably brown, glass bottle to minimize light exposure.
- Temperature: A cool and dark location is ideal for storage.
Shelf Life
Typically, a well-prepared, properly stored Liqui-Drox solution has a shelf life of around six months. However, it's always good practice to test a small batch before using it on critical evidence.
Important Note: Liqui-Drox is fantastic for dark tapes, but it's not a one-size-fits-all solution. Its effectiveness may be reduced on tapes compromised by environmental factors or exposure to excessive heat.