Chromatography
is used by scientists to separate the components of a mixture, such as
the pigments in ink. Some dyes and inks are water soluble and can be
separated using water. Others are more complex, and might need to be
separated using alcohol, or other chemicals as solvents. Forensic
investigators might test to find what inks are present in a ransom
note.
To
separate the colors in water based felt markers, investigators can
perform a simple procedure. They
can draw a horizontal line approximately 1 cm. from the bottom of a
strip of chromatography paper (coffee filter) using a black water
based marker. Tape the top of the paper on to a pencil and hang it in
a glass that has water in the bottom.
The bottom of the paper should just touch that water.
Forensic scientists can watch as the water creeps and separates
the black ink. Over a period of about 10 minutes, the water will
expose all the colors that make up that black marker.
