Paper Chromatography

Today we were detectives and used paper chromatography to figure out what colors four different black pens’ inks were made of. 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 observed that each pen’s ink was made of a unique combination of colors, even though they all looked the same before separation!

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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Lauren Koppel

Lauren earned a Bachelor’s degree with a double major of Biology and Psychology from Clark University, and a Master of Education from the Harvard Graduate School of Education. During her undergraduate years, she worked in a evolutionary neurobiology lab that studied the neural development of annelids (marine worms), with a focus on the sox family of genes. Lauren loves learning about how the world works (including everything from biology to chemistry to engineering), and is passionate about sharing that knowledge and enthusiasm with others. In the past, she has interned at the Museum of Science, where she educated learners of all ages through hands-on activities, games, and experiments. Other science education organizations with which Lauren has worked include The People’s Science, EurekaFest, and Eureka! of Girls Inc. of Worcester. Currently she lives in Boston, where devotes her free time to playing Quidditch, reading sci-fi novels, playing her ukulele, and enjoying all the culinary delights the city has to offer.

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