What are some common substances that might give a false positive when
given a luminol blood test, such as soft drinks, saliva, weeds, etc?

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Request for Question Clarification by pinkfreud-ga on 15 Dec 2005 12:27 PST

Here you'll find a long list of substances that can cause false
positives with Luminol (and also with Hemaglow):

http://www.redwop.com/technotes.asp?ID=118

If this list is fully satisfactory, I'll be glad to repost it as your
official answer. If this isn't what you need, a few more details would
be helpful.

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Clarification of Question by bjbrooks-ga on 15 Dec 2005 12:57 PST

That will work.. Thanks!

I'm glad to have been able to help you find what you needed.

As I mentioned above, there's a list here of substances that are known
to cause false positives with Luminol:
 
Lightning Powder Company: Technical Note
http://www.redwop.com/technotes.asp?ID=118

This appears to be the most detailed list of such substances that is
available for free on the Web. If you need additional detail, you may
want to consider purchasing a copy of this research article, "A study
of common interferences with the forensic luminol test for blood":

"A wide range of domestic and industrial substances that might be
mistaken for haemoglobin in the forensic luminol test for blood were
examined. The substances studied were in the categories of vegetable
or fruit pulps and juices; domestic and commercial oils; cleaning
agents; an insecticide; and various glues, paints and varnishes. A
significant number of substances in each category gave luminescence
intensities that were comparable with the intensities of undiluted
haemoglobin, when sprayed with the standard forensic solution
containing aqueous alkaline luminol and sodium perborate. In these
cases the substance could be easily mistaken for blood when the
luminol test is used, but in the remaining cases the luminescence
intensity was so weak that it is unlikely that a false-positive test
would be obtained. In a few cases the brightly emitting substance
could be distinguished from blood by a small but detectable shift of
the peak emission wavelength. The results indicated that particular
care should be taken to avoid interferences when a crime scene is
contaminated with parsnip, turnip or horseradish, and when surfaces
coated with enamel paint are involved. To a lesser extent, some care
should be taken when surfaces covered with terracotta or ceramic
tiles, polyurethane varnishes or jute and sisal matting are involved."

Wiley InterScience: Luminescence
http://www3.interscience.wiley.com/cgi-bin/abstract/85007501/ABSTRACT?CRETRY=1&SRETRY=0

My Google search strategy:

Google Web Search: forensic luminol "false positive"
://www.google.com/search?hl=en&q=forensic+luminol+%22false+positive%22

Best regards,
pinkfreud

Thanks again!