Fluorocarbons & Sulphur Hexafluoride: Fingerprint Detection

Detection of fingerprints on porous surfaces

Ninhydrin, a chemical reagent that reacts with amino acids to give a dark purple coloured product, has become the most widely used technique for fingerprint detection on paper surfaces. Prints more than 50 years of age have been developed by this process.

Over the last 30 years, different carrier solvents for ninhydrin formulations have been proposed, the most well known and the most successful being CFC-113. Ideally the carrier solvent should be non-toxic, non-flammable, non-polar (so that ink running on documents in minimised), and relatively inexpensive.
Alternatives such as pentane or hexane are to be avoided due to their high flammability. As well as being flammable, solvents such as acetone cause excessive ink running on treated documents. Several research groups around the world have studied solvents such as HFE-7100 and HFC-4310 and a number of formulations based on these two alternatives.

"The Detection and Enhancement of Latent Fingerprints" Dr Chris Lennard