You might try contacting one of the major functional GI clinics to see if there even exists in the research realm a test that will do what you want.I assume the IBS blood test from
http://www.ibsbloodtest.com is not what you are thinking of.Most IBS studies are done in human studies and track things like stool consistency and pain levels and I'm not sure there is a good way to do that in a test tube.Here is the UNC Functional GI clinic, not sure if they have any info that will help, but probably more than patients which is mostly what we have here.
http://www.med.unc.edu/medicine/fgidc/
