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New Reagents for Development of Latent Fingerprints

NCJ Number
Date Published
September 1995
2 pages
Publication Series
This paper describes research that found ways to enhance the properties (e.g., line resolution, fluorescence) of one of the most commonly used reagents in the development of latent fingerprints, ninhydrin, through structural modification; in addition, ninhydrin analogs were altered to expand their solubility to a wider range of organic solvents.
Chlorofluorocarbons, such as trichlorofifluoroethane, had been the solvents of choice in ninhydrin formulations. When banned recently by the Environmental Protection Agency, a search was begun for acceptable substitute solvents. In the ninhydrin study, researchers found that some derivatives of the reagent, resulting from its reaction with higher molecular weight or "long chain" alcohols (i.e., hemiacetals), undergo the same color-forming reactions as ninhydrin, but they are substantially more soluble in organic solvents (e.g., ethyl acetate, methylene chloride, or toluene). Hemiacetals can be quantitatively obtained from any ninhydrin analog in a one-step procedure. Several synthetic approaches were developed and evaluated to provide a total of 21 new ninhydrin analogs. These reagents were evaluated for fingerprint visualization by forensic experts at the U.S. Secret Service and other law enforcement agencies in the United States as well as in England, Switzerland, Australia, and Israel. The new methodology afforded two complementary reagents (2-THIN and 3-THIN), which displayed superior fingerprint developing properties. Large-scale production of 2-THIN has been initiated by Vinfer Ltd., a Northern Ireland manufacturer, to investigate its potential for commercialization. This research has provided a viable solution to problems encountered by criminalists as a result of the prohibition against the use of chlorofluorocarbons. 5 notes

Date Published: September 1, 1995