Paper chromatography is an analytical method that is used for separating and identifying mixtures of substances into their smaller parts. Paper chromatography works because the ink used contains several dyes (pigments) that when place on porous paper are dissolved in a solvent by capillary action. When the pigments (solutes) are dissolved in the solvent (water & alcohol mixture) they move through the paper at different rates depending on their solubility. The more soluble the pigments are the faster they will move through the paper.
Paper chromatography is most commonly used to separate pigments, dyes and inks. In forensics, paper chromatography is used in crime scene investigation and in sequencing DNA/RNA. This method can also be used to test the pH of a solution, by using pH strips. Chemist, researchers, pharmacy technicians, and pool maintenance workers are just a few professionals that use paper chromatography on a daily basis.
In this lab you will learn how to separate a sample of inks into their basic colors.
The black ink has more components then other color, when separated you will see the different pigments. that make up its color.
• Four different markers (including one black permanent marker) • Rubbing alcohol or isopropyl alcohol • Coffee filters (2) • Tall glasses or plastic cups (2) • Pencil • Ruler • Tape • Table salt • Water • Measuring cups/spoons • Clean pitcher or 2-liter bottle
1. Coffee filters usually are round, but it's easier to compare your results if the paper is rectangle. So, your first task is to cut the coffee filter into a rectangle measuring three cm by nine cm. You will need two of these strips to complete the lab.
2. Using a pencil (do not use a pen), draw a line one cm (1/2 inch) from the edge of one end of one strip of paper. [pic] 3.