Paper chromatography analyses mixtures by separating the chemical contents onto paper. For instance, chromatography is used in forensic science to separate chemical substances such as drugs in urine and blood samples. Students can perform paper chromatography projects using ink to understand how scientists are able to determine the presence of different chemicals.
Separate Ink Colors
Form an experiment to separate ink colours using paper chromatography. Hypothesise that regular black ink will show colours on the paper chromatography more noticeably than permanent ink. Set up the experiment using coffee filters and washable and permanent markers. Cut the coffee filters into long strips for each pen. Form a loop by stapling the ends of the strips together. Place a dot of ink on the bottoms of the coffee filter strips. Label each strip using a pencil, specifying the type of pen. Place the strips into a glass, then add water until it touches the bottom of the paper. Observe the strip. Compare your results between permanent marker and washable marker ink. The washable marker colours should spread out onto the paper, while the permanent marker does not because of its permanent ink.
Water vs. Rubbing Alcohol
Create an experiment to separate permanent marker ink colours using paper chromatography in water and rubbing alcohol. Hypothesise that rubbing alcohol will separate the ink colours in permanent markers, while water will not. Set up the experiment using coffee filters and permanent markers. Cut the coffee filters into long strips for each pen. Form a loop by stapling the ends of each strip together. Place a dot of ink on the bottom of the coffee filter strips. Place one strip into a glass of water and place another strip into a glass of rubbing alcohol until the fluid touches the bottom of the paper. Observe the strips. Compare your results between the water and rubbing alcohol solution. The colours should separate on the strip dipped in the rubbing alcohol, but won't separate when using water.
Conduct a paper chromatography project to find out if different types of solvents separate ink differently. Set up the experiment using coffee filters and permanent markers. Cut the coffee filters into long strips. Form a loop by stapling the ends of each strip together. Place a dot of ink on the bottom of the coffee filter strips. Place a strip each into a glass of water, rubbing alcohol, vinegar and nail polish remover. Make sure to only add liquid to touch the bottom of the strip. Observe the strips and compare results. Indicate which solvent separated the ink colours the best.
Use a Black Light
Perform an ink paper chromatography test and use a black light to determine if there are any more components visible on the paper than in regular light. Hypothesise that more components will be seen under black light, because some chemicals are invisible under white light. Make sure to look at the paper the same day the paper chromatography test was conducted in order to assure there is no fading on the paper.