The technique could be especially promising for tracking down missing or lost children, according to the researchers. Childrens fingerprints are often more difficult to detect than adults. The new method could detect prints based on chemical markers left behind in the childs fingerprints due to the presence of food, soil or saliva that can be used to track down evidence of the childs movements, the scientists say.
Traditional fingerprinting methods involve treating samples with powders, liquids or vapors to add color to the fingerprint so it can be easily photographed, a process called contrast enhancement. But fingerprints present on certain substances such as fibrous papers, textiles, wood, leather, plastic, multi-colored backgrounds and human skin can sometimes be difficult to detect by this method, according to study leader Chris Worley, Ph.D., an analytical chemist with Los Alamos National Laboratory in New Mexico. Besides permanently altering the prints, developing an effective visualization method can sometimes be time consuming, he adds.
The new technique uses a process called micro-X-ray fluorescence (MXRF), which rapidly reveals the elemental composition of a sample by irradiating it with a thin beam of X-rays without disturbing the sample. Salts such as sodium chloride and potassium chloride excreted in sweat are sometimes present in detectable quantities in fingerprints. Using MXRF, the researchers showed that they could detect the s