Page 6 - Stained With Suspicion Blood Detection

During Lab 2, students should follow correct
evidence processing procedures as they test the
substance on the carpet.

SAFETY PRECAUTIONS

1. Phenolpthalein solution is extremely
lightsensitive. When not in use, store in a dark
place so that the reagent may be used again.

NOTES

Lab 1 suggests that students test materials other than the cards for false positive reactions. The
teacher may bring in some of the items listed below for testing or ask students to volunteer to bring
one or two of these common household items for use in class the next day.

The items below may give a false positive reaction in the presumptive blood test. The teacher may
bring in any of the suggested items, as well as test any other desired substances, so that students
can see both positive and negative responses.

The following items may give a false positive on the Kastle Meyer presumptive blood test:

 Horseradish sauce
 Ketchup

 Red food coloring
 Red juice (pomegranate or cherry)

 Juice from fresh potato
 Juice from fresh horseradish

 Wasabi
 Juice from fresh cucumber

 Juice from fresh apple or pear

6 THE MYSTERY OF LYLE AND LOUISE