Forensic Lab Investigations

Chromatography Hand-written notes is often collected as evidence. Hand-written notes is often collected as evidence. Matching the ink on a note can be a valuable contribution to solving a crime. Matching the ink on a note can be a valuable contribution to solving a crime. Ex. Hitler’s Diaries Ex. Hitler’s Diaries Fake copies were made and sold copies for millions of dollars Fake copies were made and sold copies for millions of dollars Analyzed and found paper used was made in 1954, contained polyester made in 1953, and labels that were supposedly typed in 1943 were in perfect condition 9 years later Analyzed and found paper used was made in 1954, contained polyester made in 1953, and labels that were supposedly typed in 1943 were in perfect condition 9 years later

Chromatography Ink is a mix of dyes, which are water soluble Ink is a mix of dyes, which are water soluble Paper Chromatography Paper Chromatography Chemical technique used to separate the components in a mixture into a visible sequence of colored strands that serve as a pattern for matching Chemical technique used to separate the components in a mixture into a visible sequence of colored strands that serve as a pattern for matching

Chromatography Procedure: Procedure: Place a spot of ink on a strip of filter paper Place a spot of ink on a strip of filter paper Wrap the filter paper around a pencil and place the edge of the filter paper in a solvent that dissolves the ink mixture Wrap the filter paper around a pencil and place the edge of the filter paper in a solvent that dissolves the ink mixture Ex. water, alcohol Ex. water, alcohol Watch the paper soak up the solvent and take notice to some of the colors stopping before the solvent reaches the top of the paper Watch the paper soak up the solvent and take notice to some of the colors stopping before the solvent reaches the top of the paper

Chromatography Not all parts of ink mixture can “keep up” with the moving solvent Not all parts of ink mixture can “keep up” with the moving solvent Some travel full distance Some travel full distance Some lag behind Some lag behind Molecules have different characteristics (size and solubility) Molecules have different characteristics (size and solubility) Travel at different speeds Travel at different speeds Chromatogram – unique pattern of spots, colors, and distances from the starting point Chromatogram – unique pattern of spots, colors, and distances from the starting point

Chromatography Different brands of ink produce different chromatograms Different brands of ink produce different chromatograms This could be used in a crime scene to see if a note is written in the same ink This could be used in a crime scene to see if a note is written in the same ink This could also be used to check forged documents, etc. This could also be used to check forged documents, etc.