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How To Make Kastle-Meyer Solution

Presumptive Test To Detect Blood


The Kastle-Meyer test is a simple, reliable and inexpensive test to detect blood. Here is how to prepare the Kastle-Meyer solution used for the forensic test.


  • 0.1 g phenolphthalein powder
  • 25% w/v sodium hydroxide solution (aqueous)
  • 0.1 g mossy zinc
  • distilled water
  • 70% ethanol


  1. In a test tube, dissolve 0.1 g phenolphthalein in 10.0 ml of 25% sodium hydroxide solution.

  2. Add 0.1 g mossy zinc to the tube. The solution should be bright pink.

  3. Add a boiling chip and gently boil the solution until it changes color to become colorless or pale yellow. Add water, as necessary, to maintain the volume during boiling.

  4. Allow the solution to cool. Decant the liquid and dilute it to 100 ml with 70 ethanol. This is the Kastle-Meyer solution.

  5. Store the solution in a tightly-capped blue or brown bottle.

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