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
- In a test tube, dissolve 0.1 g phenolphthalein in 10.0 ml of 25% sodium hydroxide solution.
- Add 0.1 g mossy zinc to the tube. The solution should be bright pink.
- 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.
- Allow the solution to cool. Decant the liquid and dilute it to 100 ml with 70 ethanol. This is the Kastle-Meyer solution.
- Store the solution in a tightly-capped blue or brown bottle.