Urine Bioassays

[10525kfb@ibm.cl.msu.edu (Kristin Erickson)]

Hello, Radsafers:

I was watching the answers to the question on possible S35 activity, have
some things to add.

1.  Any urine that is dark in color or cloudy will read higher than clear.
Also, the number is not accurate because the optics are clouded.

2.  Use a biological sample counting cocktail that is designed to suppress
the natural chemilumninescence and other interferences in urine, blood,
etc.  This is invaluable, and we always use it for counting urines.
(Bioflour or others)

3. Many things in urine will give false positives; e.g., blood pressure
medications and others, crystals in urine cause reflection of flourescense,
and in fact, all of the many urine samples we have counted would exhibit a
higher background than non biological samples.  Chemotherapy agents
routinely interfere with our ash analysis after incineration, but quench
after several hours or a few days; this is also true in urine.  (Another
odd false positive case we had was axolotls; a researcher studied these
amphibians for his research, and could get no numbers because they produce
something that gave tremendous false positives.  I suggested the bioflour
cocktail, and, voila, wonderful data!)

4. Bleach causes false positives, in fact flouresces like the dickens if
counted immediately. Many dyes cause false positives.  Also other chemicals
cause false positive.  Some gases cause false positives; an example is
dimethylamine.

5.  If there is blood in the urine, or you have to analyze a blood sample,
use bleach to clarify and enable counting.  We add 0.5 ml at a time and
then mix, until the sample is clear and will give an accurate result.

Hope this information helps.  As you see, over the years, I have gathered a
significant body of information through unusual experiences, and hope to
save you the time of repeating analyses or decontaminating something that
is not hot.  More importantly, in urine, this may mean the difference in a
dose and possible reporting to regulators versus a non detect.

Happy counting!

Kristin

All comments herein contained are my own opinions and/or experiences and
are not necessarily those of my employer or institution.

************************************************************************
Kristin Erickson, Radiation Safety Officer
Office of Radiation, Chemical and Biological Safety
C124 Research Complex-Eng.
Michigan State University
East Lansing, Michigan 48824
Telephone: (517) 355-5008   Fax: (517)353-4871   Email: 10525kfb@msu.edu
************************************************************************