Crime Scene Investigation: How to Test for Blood

Prepare the following solution to test for the presence of blood:

Dissolve 1 to 2 grams of phenolphthalein and 25 grams of KOH (potassium hydroxide) in 100 ml of water.  Add 1 gram of zinc dust and gently heat until solution is clear.  Cool to room temperature.

The solution is now prepared and will be stable for storage.

Place solution in a dropper or spray mist bottle and label as “Meyer Reagent” and “Test for Blood”.

To test a small area:

• Saturate a swab with the solution dispensed with a dropper bottle. 
• Touch substance in question with saturated swab.  A red or pink color indicates the presence of blood.

To test a large area:

• Spray the solution onto area with a spray mist bottle.
• Observe the sprayed area; A pink color development indicates the presence of blood.

*always wear gloves when working with solutions and bodily fluids