Paper Chromatography

Today we were detectives and used paper chromatography to figure out which of four different black pens were used to make “unknown” chromatographs. Paper chromatography is a separation technique in which dots of pigment, in our case ink, are placed on special filter paper and the paper is then dipped into a solvent. We used 70% rubbing alcohol as the solvent, and as the alcohol traveled up the paper, it dissolved the dots of ink and carried them along with it. Since black ink is actually a mixture of several different colors, or pigments, the colors get spread out on the paper because they have different affinities to the paper. At the end of the experiment, we took the papers out of the alcohol and these were our chromatographs.

We then were able to compare our chromatographs to the “unknown” chromatograph to figure out which pen’s ink was used to make it!

Cromatografía en Papel

Hoy fuimos detectives y utilizamos la cromatografía en papel para determinar cuál de cuatro lápices negros fue usado para hacer un cromatograma de procedencia desconocida. La cromatografía en papel es una técnica de “separación” en la cual puntos de pigmentos de tinta son puestos sobre un papel filtro especial que luego es sumergido en un solvente, alcohol al 70%. Mientras el alcohol viaja a través del papel, disuelve los puntos de tinta arrastrándolos consigo. Dado que la tinta negra es una mezcla de colores o diferentes pigmentos, estos se van separando en el papel de acuerdo a sus diferentes afinidades por este. Finalmente removimos los papeles del alcohol y obtuvimos nuestros “cromatogramas”.

Luego comparamos nuestros cromatógrafos con el cromatograma “desconocido” y fuimos capaces de identificar qué tipo de lápiz fue utilizado para hacerlo.


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