In autopsy, preservative used for vitreous is

Vitreous humor is the preferred specimen for postmoem confirmation of alcohol ingestion, since postmoem formation of ethanol does not occur to significant extent in vitreous, and hence useful even in decomposing bodies. It is recommended that this specimen is included routinely in sudden death investigations. In known diabetics, it is always wise to check the postmoem vitreous glucose level, even when there seems to be some other plausible cause of death. A high vitreous glucose level (> 200 mg/dl or so) is likely reflective of hyperglycaemia. Vitreous humor is preserved using sodium fluoride (10 mg/ml). Ref - Krishan Vij textbook of forensic medicine and toxicology 5e pg : 107 ,445