The ninhydrin process in supercritical carbon dioxide

Ninhydrin is a widely used reagent for the development of latent fingerprints on porous surfaces. For the past 20 years 1,1,2-trichlorotrifluoroethane (CFC113) has been used as the solvent of choice in the UK for ninhydrin because of its non-toxicity and non-flammability. With the phasing out of CFC solvents under the terms of the Montreal Protocol on the Control of Ozone Depleting Substances, the need for a suitable replacement has arisen. Supercritical CO2 has been found to be a potential replacement for CFCI13 in the ninhydrin process. Furthermore, the present processes are two-stage (impregnation of reagent followed by development in an oven), whereas using supercritical CO2 development of fingerprints can be carried out in one stage.