5-MTN is a close relative of ninhydrin, a staple in latent print development. They share a similar chemical structure and both primarily target amino acids present in fingerprint residue. Here's what makes 5-MTN special:
- Enhanced Color: Prints developed with 5-MTN have a more intense purple coloration than regular ninhydrin, allowing for better visualization. This means you can use a less concentrated solution.
- Strong Fluorescence: After a subsequent treatment with zinc chloride, the 5-MTN-developed prints exhibit strong fluorescence, particularly under green light excitation. This allows for enhanced detection on difficult surfaces.
Equipment
- Fume Hood: Essential for safety due to the solvents used.
- Shallow Trays or Tanks: For dipping evidence.
- Drying Rack/Area: A well-ventilated space to hang evidence for drying.
- Personal Protective Equipment: Gloves, lab coat, eye protection, respirator (if fume hood unavailable).
Ingredients for 1-Liter 5-MTN Solution
- 5-MTN: Approximately 3 grams (adjust as needed for desired color intensity)
- HFE-7100 997 ml (This is a common solvent; other suitable alternatives exist)
- Acetic Acid: 3 ml
Mixing Procedure
- Safety First: Work inside a fume hood and don your PPE.
- Dissolve: Thoroughly dissolve the 5-MTN in the HFE-7100 using gentle stirring (magnetic stirrers can help).
- Add Acetic Acid: Slowly stir in the acetic acid.
- Storage: Transfer the solution to an amber bottle for proper storage. Label clearly with the reagent name, date, and any hazard information.
Latent Print Processing with 5-MTN
- Submerge Evidence: Immerse porous evidence (like paper) in the 5-MTN solution within your fume hood.
- Dry: Remove the evidence and hang it to dry completely in a well-ventilated area.
- Heat and Humidity: Development can be accelerated in a humidity chamber or by using gentle heat. Remember to follow your lab's standard procedures.
- Zinc Chloride (Optional): For fluorescence enhancement, treat the developed prints with a zinc chloride solution.
- Visualization and Documentation: Examine developed prints under white light and then with a forensic light source (green light is optimal for fluorescence) and appropriate camera filters. Document according to lab protocols.
Storage and Shelf Life
- Light Sensitivity: Store your 5-MTN solution in an amber bottle to minimize light exposure.
- Cool Conditions: Ideally, store it in a refrigerator.
- Shelf Life: A properly mixed and stored 5-MTN solution can have a shelf life of 6 months or more. However, always inspect the solution before use as performance can degrade over time.
Important Considerations
- 5-MTN works best on porous surfaces like paper.
- Always perform testing and comparison with your current methods before fully implementing a new reagent like 5-MTN.
- Exercise caution as the solvents used are flammable and can be hazardous. Prioritize safety!