The Japanese Association of Science and Technology for Identification

Japanese Journal of Science and Technology for Identification , 5 (1), pp. 23 - 32 , 2000

Fluorescent Enhancement of Ninhydrin and 5-Methoxyninhydrin Developed Fingerprints by Indium Trichloride.

Masahisa Takatsu, Noriaki Sumida, Yukinori Tateishi, Osamu Shimoda

Abstract
Ninhydrin has been the most widely used reagent for developing a latent finger- print on paper. And a few kinds of lib 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 con- ventional 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 526nm which was compatible with a 532nm 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 finger- prints.

Keywords: Development of latent fingerprint, Ninhydrin, 5-Methoxyninhydrin, Fluorescence, Indium trichloride, Nd : YVO₄ laser

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