If you think that the pesticide is bound to protein and won't come off with
a particular extraction then it is possible to digest a small amount of the
fecal material with protease K and/or other general proteases. Which solvent
you choose for extraction of the fecal material will depend on the
properties of your pesticide and its metabolites (hydrophobic/hydrophilic,
etc.,). There are lots of protocols at US EPA and on Medline, and they vary
depending on what you want to extract. If there is not a specific protocol
for your pesticide, then you will probably have to go with the classical
"spike the sample with a known amount of pesticide and measure recovery"
approach until you find a method that works well. It would be helpful and
make life easier if your pesticide had a radioactive label. :>)
Charles Miller, Ph.D.
Environmental Health Sciences Dept.
Tulane University Health Sciences Center
New Orleans, LA 70112
504-585-6942, rellim at tulane.edu