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How to Use the Fingerprint Technique in Chemistry

One way criminologists and prosecutors link perpetrators to crimes is through fingerprinting. Advanced fingerprinting technology using chemistry has given criminologists more sophisticated tools to identify those criminals. In particular, latent prints can provide needed chemical information to solve a crime. This technique uses chemical procedures for in-depth analysis. The prints are formed by sweat or oil from the fingers to a surface that is smooth enough to maintain the print. They cannot be seen by the human eye.

Things You'll Need

printing powder
brush

Instructions

- 1
  Apply a dark fingerprinting powder to surfaces with potential prints. Brush the powder carefully to determine if a print was left. The best prints are found on glass, varnished woods, painted surfaces, various metals and paper.
- 2
  Remove fingerprint samples from the crime scene and bring them to a lab. Process a full fingerprint signature through micro-X-ray fluorescence (MXRF). This X-ray highlights the chemical composition and structure of fingerprints by extracting data from the salts, such as sodium chloride and potassium chloride, excreted by sweat.
- 3
  Examine the fingerprints through the MXRF for blood, smudges, dirt or other distortions. Eliminate these distortions from your scan. The type of fingerprint patterns include arch, loop and whorl, which will be displayed in the MXRF scan.
- 4
  Complete the full fingerprint sample by using the scan from the MXRF. It will provide data on the chemical composition of the fingerprint, as well as give you an idea on how to make out shapes such as arches, loops and whorles.

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