Kastle–Meyer test

Kastle–Meyer test is a forensic presumptive blood test, first described in 1903, in which the chemical indicator phenolphthalein is used to detect the possible presence of hemoglobin. It relies on the peroxidase-like activity of hemoglobin in blood to catalyze the oxidation of phenolphthalein (which is colorless) into phenolphthalein (which is pink) in the presence of hydrogen peroxide.

Procedure

The Kastle–Meyer test is performed by collecting a sample that is suspected to contain blood and applying it onto a piece of filter paper. A few drops of alcohol, then phenolphthalein, and then hydrogen peroxide are applied to the sample. If the sample turns pink rapidly, it is said to test positive for blood.

Reliability

The Kastle–Meyer test is extremely sensitive and can detect blood in concentrations as low as 1:10^7. However, it is a presumptive test and can yield false positives from substances such as copper and certain vegetable materials. Therefore, a positive result must be confirmed by a more specific test, such as the Teichmann test or the Takayama test.

Limitations

The Kastle–Meyer test cannot differentiate between human and animal blood. It also cannot determine the age of the blood stain or the blood type. Furthermore, certain cleaning agents can interfere with the test and cause false negatives.

Applications

The Kastle–Meyer test is widely used in forensic science to detect traces of blood at crime scenes. It is also used in environmental science to test for the presence of blood in water samples.

See also

• Luminol
• Leucomalachite green
• Hemastix

References

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