Ink chromatography

Summary

This video demonstrates ink chromatography, a forensic technique to identify ink used in crime scenes. The presenter uses different pens to make marks on filter paper, then submerges the paper in methylated spirits. The ink separates into different colors based on solubility, creating a unique pattern. By comparing these patterns, forensic scientists can determine the pen used at a crime scene.

Takeaways

• 🔍 Ink chromatography is a forensic technique used to analyze ink from different pens.
• 🖊️ The demonstration uses normal filter paper or paper towel to absorb the ink.
• 📝 Pens are labeled to track which one is the 'crime scene pen'.
• 🎨 A series of ink dots are made on the paper to represent samples.
• 🏷️ A paddle pop stick is used to hold the paper without covering the ink dots.
• 🚫 It's crucial not to cover the ink dots when performing the test.
• 🌀 Methylated spirits are used to draw the ink up through the filter paper by capillary action.
• 🌈 The ink separates into different colors based on the solubility of its components.
• 🔵 The least soluble color travels the shortest distance, while the most soluble stretches out the farthest.
• 🕵️‍♂️ Scientists can use the unique color patterns to identify the pen used at a crime scene.
• 📚 Chromatography is the scientific process that allows for the separation and identification of substances.

Q & A

What is ink chromatography?

Ink chromatography is a forensic technique used to separate the different components of ink from a pen. It helps in identifying the type of pen used based on the pattern of ink separation.

What materials are needed for ink chromatography?

For ink chromatography, you need different pens, normal filter paper or paper towel, a pencil, a paddle pop stick, and methylene spirits.

Why is filter paper or paper towel used in the process?

Filter paper or paper towel is used because it can absorb the liquid, allowing the methylene spirits to draw up through the paper and separate the ink into different colors.

How are the pens labeled in the script?

The pens are labeled numerically, and one of them is secretly designated as the 'crime scene pen' without revealing which one it is.

What is the role of the paddle pop stick in the experiment?

The paddle pop stick is used to hold the filter paper in place so that it doesn't fall over in the liquid during the chromatography process.

Why is it important not to cover the ink dots with methylene spirits?

It's important not to cover the ink dots because the methylene spirits need to be applied around the back of the paper to allow capillary action to draw the spirits up through the paper and separate the ink.

What is capillary action and how does it relate to ink chromatography?

Capillary action is the ability of a liquid to flow in narrow spaces without the assistance of external forces like gravity. In ink chromatography, it's used to draw the methylene spirits up through the filter paper, which in turn separates the ink into its constituent colors.

How does the separation of ink occur?

The separation of ink occurs based on the solubility of the ink's pigments. The least soluble colors do not travel as far, while the most soluble colors stretch out the furthest.

What is the significance of the different colors in the separated ink?

The different colors in the separated ink indicate the various pigments present in the ink, which can be used to create a unique pattern. This pattern can help forensic scientists identify the pen used at a crime scene.

How can the pattern of ink separation help in a forensic investigation?

The pattern of ink separation can help in a forensic investigation by providing a unique 'fingerprint' for each pen. This can be compared to ink samples from a crime scene to potentially identify the pen used.

Why does the presenter think that the crime scene pen is not pen number 4?

The presenter thinks that the crime scene pen is not pen number 4 because the crime scene ink has a lot more blue in it, which is not observed in the separation pattern of pen number 4.

What conclusion can be drawn from the ink chromatography experiment in the script?

From the experiment, it can be concluded that each pen leaves a unique pattern when its ink is separated, which can be a valuable tool in forensic analysis to match ink samples from crime scenes.