Bouin's solution is a popular fixative for embryonic studies and skin, due to its excellent preservation of nuclei and chromosomes. Bouin's is very compatible with the trichrome stain due to its mordanting effect on the tissue.
Fixation: Tissues fixed in Bouin's solution should be changed to 70% ethanol after 4-48 hours of fixation (less than 24 hours is optimal). If the tissues are fixed longer than this they tend to become brittle and difficult to section. (NOTE: long term storage in 70% ethanol can lead to shrinkage of the tissue)
Hazards: Bouin's solution contains formaldehyde (more on formaldehyde). Bouin's solution also contains Picric acid (which gives the solution its yellow color). Picric acid is highly explosive when dry. If your lab has a stock bottle of Picric Acid that does not have a layer of liquid in it, CALL YOUR SAFETY/RISK MANAGEMENT PEOPLE IMMEDIATELY FOR DISPOSAL, DO NOT ATTEMPT TO HANDLE THE BOTTLE YOURSELF. For MSDS information on Picric Acid, you can locate an appropriate MSDS at the Vermont SIRI MSDS Archive.
Recommendations: If you are not a frequent user of Bouin's solution, we recommend you consider purchasing small quantities of your fixative premade from any one of a number of suppliers. This reduces hazardous waste, removes the Picric Acid hazard and ensures fresh fixative.
University of Arizona Risk Management - 520-621-5861
Andrea Grantham, HT (ASCP) and Frank Walmsley, B.S., HT (ASCP) of the (now closed) CMM Histology Service Laboratory assisted in the development of this page.