Latent fingermark development using low-vacuum vaporization of ninhydrin

Area of Science:

• Forensic Science
• Analytical Chemistry
• Green Chemistry

Background:

• The vacuum technique for reagent vaporization is underutilized for latent fingerprint development.
• Traditional methods often involve hazardous solvents, posing environmental and health risks.

Purpose of the Study:

• To introduce and evaluate a homemade vacuum system for developing latent fingerprints using solid ninhydrin.
• To explore solvent-free alternatives for fingerprint detection, promoting green chemistry principles.

Main Methods:

• Utilized a custom-built fume hood with vacuum and programmable heating control.
• Investigated factors influencing performance: chemical quantity, heating program, and substrate material.
• Vaporized solid ninhydrin under low-vacuum conditions (50 mTorr) at 80-90 °C.

Main Results:

• Effectively developed latent fingerprints by vaporizing solid ninhydrin.
• Achieved successful development on thermal paper and banknotes (Taiwan, US) without discoloration or damage.
• Identified optimal temperature range (80-90 °C) for efficient ninhydrin vaporization.

Conclusions:

• The vacuum vaporization technique provides a reliable, solvent-free method for latent fingerprint development.
• This approach aligns with environmental protection and green chemistry initiatives.
• Further research is needed to optimize settings for diverse banknote surfaces due to variations in physical properties.