OAKWOOD AP FORENSICS MYSTERY WHO DONE IT?

Kastle-Meyer Test

Kastle-Meyer Test In the early 1900’s, Dr. Kastle developed a presumptive test for hemoglobin which used phenolphthalein as a color indicator. A few years later, Dr. Meyer refined and improved upon this test, and this is why it is sometimes called the Kastle-Meyer test.

H2O2 is a by-product of cellular reactions… (remember that?)

The HEME in your RBC, acts as the peroxidase...

It breaks up the H2O2...

The O combine with the KM, our phenolphthalein color-indicator.

Initially, the KM is boiled for several hours (this rids it of Oxygen)

When the solution turns colorless, that means the KM has had most of its oxygen removed, and is now "oxygen hungry".

So... now we have the makings of a kind of love story: the KM is badly in want of oxygen, and there's a lonely oxygen radical floating around, un-spoken for... What do you suppose happens next?

Pink color: This is the blushing that occurs when the oxygen radical "hooks up" with the KM reagent. The radical oxidizes the KM, and this oxidation causes the KM to turn pink.

This test is capable of detecting blood spots practically invisible to the naked eye.

In a criminal case, a positive Kastle-Meyer test would be followed by tests to determine the species that produced the blood...

If human, tests would be performed to determine ABO and Rh groups. Multiple alleles If human, tests would be performed to determine ABO and Rh groups.