Stability of barbiturates in fixed tissues and formalin solutions.

This study reports the results of the retention and quantitation of barbiturates in fresh tissue, in liver tissue fixed in formalin, and in the formalin solutions in which the same tissues were fixed for six months. Biological materials came from four cases of death due to phenobarbital and two due to butalbital. Results showed the presence of barbiturates in all studied materials. Mean recovery rates of phenobarbital in fixed liver were 57.11% and 30.84% in formalin from liver; and those of butalbital in fixed liver were 21.66% and 66.56% in formalin from liver. Total sums of recovery rates in formalin solutions and fixed tissues for phenobarbital (87.95%) and butalbital (88.22%) were comparable with those of the extraction efficiency of the method (90.2%) and indicate that these barbiturates have good stability even in biological specimens subjected to chemical fixation. This fact may be useful in qualitative evaluation of cases.