Chromatography Analysis of Black Pens to Determine Unknown Sample Purpose:
Paper chromatography was performed on five different black pens, using four different solutions to determine which would be most appropriate to use on an unknown sample. Paper chromatography was then performed on the unknown sample to identify which pen was used to create it. Procedure:
Each person participating in the analysis was assigned one solution to work with: V. Temple used distilled water, D. Sellers used a 20% ethanol solution, J. Chadwick used a 50% ethanol solution and J. Sanchez used a 90% ethanol solution. Each participant used the same procedure with their assigned solution, repeating it for each of five ink samples. The pens used were a Sanford Vis a vis, a Sharpie fine point, a Dixon Visaid, a Sharpie calligraphy and a generic felt tip. A strip of chromatography paper measuring about 13 cm x 2.5 cm was marked with pencil 2.5cm from one edge, on this line a pen was used to mark a dot. The marked end of the strip was then suspended in solution to a depth of about 1 cm without allowing the strip to touch the bottom of the container. The strip was then allowed to react with the solution until the solution travelled to a height of about 10 cm. This was repeated with each pen being tested in each solution. After the solution had travelled about 10 cm, the chromatography strips were removed and allowed to dry while suspended. When dry Rf values were calculated for each pen type in each type of solution by dividing the distance each color from a sample travelled by the total distance the solution travelled in that sample. From the results of this test a consensus was reached to use distilled water and a 50% ethanol solution to test the two unknown samples. The same procedure as above was repeated to determine which pen was used to make the unknown samples. Water and 50% ethanol were chosen for clarity of separation of ink components and clarity of color...
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