抄録
Ninhydrin has been the most widely used reagent for developing a latent fingerprint on paper. And a few kinds of IIb metal salt are known to form fluorescent coordination complex with Ruhemann's purple (RP), the reaction product of ninhydrin with amino acid. In this paper, fifteen kinds of metal chloride including conventional zinc chloride have been evaluated on the coloriation intensing enhancement of RP obtained from L-glutamic acid with ninhydrin using a spectrophotometer. At B excitation (450-490 nm) and G excitation (510-560 nm), indium trichloride gave an excellent result. The absorption maximum of the complex obtained was observed at 510 nm. Furthermore, indium trichloride was applied to the RP from L-glutamic acid with 5-methoxyninhydrin. The absorption maximum was observed at 526 nm which was compatible with a 532 nm green line of a Nd:YVO4 laser. Fluorescence of fingerprints of 5-methoxyninhydrin/indium trichloride treatment was considerably stronger than that of 5-methoxyninhydrin/zinc chloride treatment when excited by the green line. Furthermore, the fingerprints treated with ninhydrin/indium trichloride could also be excited by the laser and its fluorescence intensity was almost equivalent as to that treated with 5-methoxyninhydrin/zinc chloride. Ninhydrin/indium trichloride may be useful for the practical development of fingerprints.
