Science Buddies: "Ask an Expert"

During the kastle meyer test when we use the blood strips why does it change color, also what type of chemical are in the strip that cause to react to a different color?

Hello!

That is a great question. Have you checked out the page on science buddies called Crime Scene Chemistry? You can find it here https://www.sciencebuddies.org/science- ... background. It provides some background as to how the Kastle meyer test works.

In brief, the test uses the iron in hemoglobin (a component of red blood cells). There is a reaction which causes the oxidation of phenolphthalin to phenolphthalein. Phenolphthalin is the chemical in the Kastle meyer test and normally has no color, but when blood and hydrogen peroxide are there the phenolphthalin changes to phenolphthalein, resulting in the pink color.

Are you doing some research on this for your science project?

~Nikki

Thank you so much. Yes this is my project for science fair.

How does the kastle meyer test effect people and does it really effect hurt people during the testing of the blood?

Hi there,

The Kastle-Meyer test is a forensic test that is usually used to detect whether blood is present at a crime scene, for example. This test is not usually performed on a person, but rather on swabs from places around scenes being investigated.

Were you planning to do an experiment involving the Kastle-Meyer test?

Heather

Ya i know that the Kaslte Meyer test is use during the a crime scene. And yes i am Planning to do an Experiment involving The Kastle Meyer test.

Great! What did you have in mind? Let us know if you need feedback on your experimental design.

How can you tell if its blood or not without using the Kastle Meyer test? will any one be able to know or just the people who test can tell cause they may see and test almost everyday most likely?

Hi there,

Another way to test whether something is blood is to view the sample under a powerful microscope. However, the Kastle Meyer test is usually used in situations for which it is difficult to tell whether it is blood - for example, there are very trace amounts which may or may not be visible to the naked eye.

The test reacts with the hemoglobin (iron-containing compound) in blood via a chemical reaction. So you do not have to see the blood to test for it.

I hope that answers your question.

Heather